Enhanced physical properties of polymer composites with mixed morphology three-dimensional graphene

Abstract

A composite material includes a polymer and a graphene-containing material having nodular and / or flaky morphologies. The composite material has a glass transition temperature that is at least 3 °C higher than a glass transition temperature of the polymer in absence of the graphene-containing material. A composite material includes a polymer and a three-dimensional graphene, where the composite material has a mechanical strength above 5 MPa at a temperature above 90 °C.

Description

DOCKET: LYT1P134.P_LYTEP322WOENHANCED PHYSICAL PROPERTIES OF POLYMER COMPOSITES WITH MIXED MORPHOLOGY THREE-DIMENSIONAL GRAPHENECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 791,269, titled “Pristine Carbons as Energy Well in Epoxy Resin,” filed April 18, 2025, U.S. Provisional Patent Application No. 63 / 794,217, titled “Enhanced Mechanical Properties of Structural Epoxy Resin with Three-Dimensional Graphene,” filed April 24, 2025, U.S. Provisional Patent Application No. 63 / 824,765, titled “Enhanced Mechanical Properties of Epoxy Adhesive with Three-Dimensional Graphene,” filed June 16, 2025, and U.S. Provisional Patent Application No.63 / 909,541, titled “Pristine Carbons as Energy Well in Epoxy Resin,” filed October 31, 2025, all of which are incorporated by reference in their entirety.FIELD OF THE INVENTION

[0002] This disclosure relates to polymers, especially pertaining to graphenecontaining material dispersed in polymer material. More particularly, the inventive concepts presented herein relate to enhanced physical properties of polymer composites with mixed morphology three-dimensional graphene (3DG).BACKGROUND

[0003] Ongoing efforts in the field of material synthesis seek continuing improvements in the quality and efficiency of fabricating various compositions of matter for myriad industrial, commercial, locomotive, and other applications. Of particular interest is the ability to fabricate stronger, lighter materials while concurrently reducing the cost of fabrication, both from a financial perspective and in terms of reducing amount of raw materials required to produce final products.-2- LYT IP 134.P_LYTEP322WO

[0004] Graphene remains a material of interest in a growing field of practical applications and is a major focus for development and advancement of materials science, particularly composite materials. However, substantial challenges and obstacles have thus far presented equally substantial limitations on the ability to synthesize materials theorized to be capable of conveying advantageous characteristics such as mechanical strength, thermal and electrical conductivity, chemical stability, specific chemical functionality, etc. as known in the art.

[0005] Among these challenges include the capacity to dissolve, incorporate, integrate, infuse, coordinate, or otherwise combine or include graphene in various base materials to form desired composites, particularly in amounts exceeding about 1-5 wt% (depending on the base materials and fabrication techniques in question). Rather than dissolving into the native structure of the base material (e.g., a crystalline lattice, a polymer matrix, etc.), in amounts greater than about 1-5 wt% graphene tends to precipitate and form agglomerates and occupy space adjacent to the base material (e.g., in grain boundaries, at peripheral sites, on external surfaces, etc.). Given the low amounts of graphene that can be included in the base material native structure, achieving uniform dispersion or homogenous distribution of carbon in the base material native structure remains yet another unfulfilled objective.

[0006] Moreover, the resulting composite materials tend to include polar covalent bonds between the carbon atoms of the graphene and / or between carbon atoms of the graphene and atoms of the base material, as well as including ionic bonds between atoms of the base material. These types of bonds undesirably alter (and may even dictate) the electronic properties of the composite material, further frustrating efforts to develop new composites with desired chemical and electrical properties.

[0007] Further still, conventional fabrication techniques and apparatuses (such as legacy plasma flame, plasma spray, induction melting, and plasma spark sintering techniques, etc.) are unsuitable for forming composite materials having the desired characteristics noted above. While conventional techniques may be capable of producing diamond, or diamond-like carbon, these carbon materials form on the surface of the base material rather than dissolving into the base material structure (e.g., occupying sites of the lattice or matrix, or being present in interstitial sites of a crystalline lattice, etc.).-3- LYT IP 134.P_LYTEP322WO

[0008] Accordingly, there is both a well-documented need and long-felt desire to overcome the foregoing challenges and obstacles, realizing the ability to synthesize graphene composite materials with graphene present (e.g., dissolved) in the native structure of the base material (e.g., crystalline lattice or polymeric matrix), uniformly dispersed throughout the base material, present in amounts greater than about 5 wt%, and / or where the graphene is “prislinc” such that the composite substantially lacks defects, and / or carbon agglomerates, particularly in or at grain boundaries.

[0009] Epoxy adhesive, for instance, is a polymer matrix that is difficult to obtain homogenous dispersion of graphene throughout the polymer matrix. Moreover, the non-reactive surface of graphene tends to prevent good adhesion bonding that in term limits the load transfer from graphene to the polymer. A graphene-epoxy adhesive composite remains elusive that provides increased tensile strength and enhanced adhesion.-4- LYT IP 134.P_LYTEP322WOSUMMARY

[0010] This Summary is provided to introduce in a simplified form a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. Moreover, the systems, methods, and devices of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

[0011] According to one aspect, a composite material includes a polymer and a graphene-containing material having nodular and / or flaky morphologies. The composite material has a glass transition temperature (Tg) that is at least three degrees Celsius (3°C) higher than a Tg of the polymer in absence of the graphene-containing material.

[0012] According to other aspects of the present disclosure, the graphenecontaining material of the composite material is a three-dimensional graphene (3DG). In one aspect, the graphene-containing material is essentially free of oxygencontaining species. In one aspect, the graphene-containing material is essentially pure carbon. The graphene-containing material is dispersed uniformly in the polymer. In one aspect, the polymer is an epoxy adhesive resin.

[0013] According to another aspect of the present disclosure, nodular morphologies of the graphene-containing material are configured to inhibit crack initiation and propagation of the composite material during impaction of shock, force, etc. to the composite material.

[0014] According to another aspect of the present disclosure, the composite material has an exotherm enthalpy at least 10% lower than an exotherm enthalpy of the polymer in absence of the graphene-containing material during curing. In one aspect, the composite material has a mechanical strength at least 4% higher than a mechanical of the polymer in absence of the graphene-containing material at an elevated temperature of at least 90 °C. In another aspect, the composite material has a-5- LYT IP 134.P_LYTEP322WOtensile lap shear strength at least 5% higher than the polymer in absence of the graphene-containing material.

[0015] According to one aspect, a composite material includes a polymer and a three-dimensional graphene, where the composite material has a mechanical strength above 5 MPa at a temperature above 90 °C.

[0016] According to other aspects of the present disclosure, the 3DG of the composite material is an unfunctionalized 3DG. In one aspect, the composite material has a tensile lap shear strength above 5 MPa at a temperature above 90 °C.

[0017] According to yet other aspects of the present disclosure, the polymer is an epoxy resin. In preferred aspects, the polymer is an epoxy adhesive resin. The composite material is an adhesive that is configured to bond a first material to a second material, where the first and second materials have different compositions. In one aspect, the first material is a polymer material, and the second material is a metal.

[0018] According to one aspect, the composite material is an adhesive that is configured to adhere to an adherend. In one aspect, a Tg of the adhesive is higher than a Tg of the adherend. In various aspects, the adherend may include a polymer material, a carbon fiber reinforced polymer material, etc.

[0019] Further details of aspects, objectives, and advantages of the technological aspects are described herein, and in the drawings and claims. The foregoing general description of the illustrative aspects and the following detailed description thereof are merely exemplary aspects of the teachings of this disclosure and are not restrictive.-6- LYT IP 134.P_LYTEP322WOBRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described below are for illustration purposes only. The drawings are not intended to limit the scope of the present disclosure. This patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawings will be provided by the U.S. Patent and Trademark Office upon request and payment of the necessary fee.

[0021] FIG. 1A through FIG. 1Y depict structured carbons, various carbon nanoparticles, various carbon-containing aggregates, and various three-dimensional carbon-containing structures that are grown over other materials, according to some aspects of the present disclosure

[0022] FIG. 2A are transmission electron microscopy (TEM) images of three-dimensional graphene having different morphologies, according to some aspects of the present disclosure. Part (a) is a flake morphology, part (b) is a nodular morphology, part (c) is a crumpled graphene morphology, and part (d) is a crusty donut morphology.

[0023] FIG. 2B are scanning electron micrograph (SEM) images of conventional graphene oxide (part (a)) and reduced graphene oxide (part (b)).

[0024] FIG. 3 is a scanning electron micrograph (SEM) images of a sample of an unfunctionalized three-dimensional graphene, according to one aspect.

[0025] FIG. 4 illustrates a scheinalic drawing of the physical effects on a composite of epoxy polymer and 3DG, according to one aspect. Part (a) illustrates the effects of force shock on a polymer matrix having nodular 3DG, and part (b) illustrates the effects of force shock on a polymer matrix having flaky 3DG.

[0026] FIGS. 5A and 5B illustrate plots of heat flow measurements in DSC testing of neat epoxy adhesive (EA) and a composite of epoxy adhesive with 3DG, according to one aspect.

[0027] FIG. 6 is an image of a peel test of a neat epoxy adhesive and a composite of epoxy adhesive with unfunctionalized 3DG, according to one aspect.-7- LYT IP 134.P_LYTEP322WO

[0028] FIG. 7 is a plot heat flow measurement in DSC testing of a composite of epoxy adhesive with unfunctionalized 3DG (EA 3DG) compared to commercially available structural adhesive formulations Ad 1 and Ad 2, according to one aspect.

[0029] FIG. 8 is a plot of shear strength measurements of a composite of epoxy adhesive with unfunctionalized 3DG (EA 3DG) compared to commercially available epoxy adhesive formulations Ad 1 and Ad 2 on an aluminum (Al-Al) substrate at elevated temperatures, according to one aspect.

[0030] FIG. 9 is a plot of shear strength measurements of a composite of epoxy adhesive with unfunctionalized 3DG (EA 3DG) compared to commercially available structural adhesive formulations Ad 1 and Ad 2 on a carbon fiber reinforced polymer (CFRP-CFRP) substrate at room temperature and elevated temperatures, according to one aspect.

[0031] FIG. 10A depicts transmission electron microscopy (TEM) images of silicon-doped amine-functionalized three-dimensional graphene (Amine29), according to some aspects of the present disclosure. Part (a) TEM image, part (b) TEM-electron energy loss spectrophotometry (EELS) elemental analysis.

[0032] FIG. 10B depicts transmission electron microscopy (TEM) images of silicon-doped amine-functionalized three-dimensional graphene (Amine29), according to some aspects of the present disclosure. Parts (a) and (b) TEM image and TEM-EELS elemental analysis images of a portion having nodular and flaky morphology, parts (c) and (d) TEM image and TEM-EELS elemental analysis of a portion having carbon nodules and flakes with oxygen localized on the outer edge. Part (e) is a TEM-EELS elemental analysis of a magnified view of an edge portion of the amine-functionalized graphene.

[0033] FIG. 10C depicts transmission electron microscopy (TEM) images of silicon-doped amine-functionalized three-dimensional graphene (Amine29), according to some aspects of the present disclosure. Parts (a) and (b) TEM image and TEM-EELS elemental analysis images of a portion having nodular morphology with silicon oxygen compounds localized on the outer edge., parts (c) and (d) TEM image and TEM-EELS elemental analysis of a magnified view of a portion having carbon nodules.-8- LYT IP 134.P_LYTEP322WO

[0034] FIG. 10D depicts transmission electron microscopy (TEM) images of silicon-doped amine-functionalized three-dimensional graphene (Amine29), according to some aspects of the present disclosure. Part (a) illustrates a TEM image of an edge portion of a graphilic particle, and part (b) is a magnified view (from the inset box on part (a)) of TEM-EELS elemental analysis of the edge portion. Part (c) is a further magnified view of a portion with silicon-oxygen compounds associated with carbon nodule.

[0035] FIG. 11 depicts images of amine-functionalized graphene uniformly distributed in the epoxy adhesive, according to some aspects of the present disclosure. Part (a) is an image of uncured and cured samples of epoxy adhesive loaded with amine-functionalized 3DG, parts (b) and (d) are magnified images of Part B loaded with amine-functionalized 3DG (uncured), and parts (c) and (e) are magnified images of cured epoxy adhesive loaded with amine-functionalized 3DG.

[0036] FIG. 12 is a plot of the Tensile Lap Shear Strength (TLSS) of epoxy adhesive loaded with amine-functionalized 3DG, according to one aspect of the present disclosure.

[0037] FIG. 13 is a plot of the Tensile Lap Shear Strength (TLSS) of epoxy adhesive loaded with amine-functionalized 3DG compared to epoxy adhesive loaded with graphene oxide and reduced graphene oxide, according to one aspect of the present disclosure.

[0038] FIG. 14 is a plot of the Tensile Lap Shear Strength (TLSS) of 2-part epoxy adhesive loaded with amine-functionalized 3DG compared to a commercially available 2-part epoxy adhesive without graphene, according to one aspect of the present disclosure.

[0039] FIG. 15 is a schematic representation of a method of ball milling graphene.

[0040] FIG. 16 depicts scanning electron micrograph (SEM) images of silicon-doped three-dimensional graphene, according to some aspects of the present disclosure. Part (a) Si42, part (b) Si49, part (c) Si50, part (d) Si51 , and part (e) Si52.-9- LYT IP 134.P_LYTEP322WO

[0041] FIG. 17A illustrates characteristics of a silicon-doped three-dimensional graphene having graphitic particle morphology, according to one aspect of the present disclosure. Part (a) depicts a high magnification transmission electron microscopy (TEM) image of a graphitic particles, part (b) depicts a histogram of measured lengths of graphitic particles.

[0042] FIG. 17B illustrates characteristics of a silicon-doped three-dimensional graphene having flaky morphology, according to one aspect of the present disclosure. Part (a) depicts a high magnification transmission electron microscopy (TEM) image of a flakes, part (b) is a table of aspect ratio of flakes, part (c) is a table of average flake length.

[0043] FIGS. 18A-18D depict images that illustrate morphological aspects of silicon-doped three-dimensional graphene samples Si53 and Si54, according to one aspect of the present disclosure. FIG. 18A depicts a transmission electron microscopy (TEM) images: part (a) Si53 having graphitic particles and flakes, part (b) Si54 having predominately nodules.

[0044] FIG. 18B depicts scanning transmission electron microscopy (STEM) images: part (a) Si53 having graphitic particles and flakes, part (b) Si54 having predominate nodules.

[0045] FIG. 18C depicts TEM images and TEM-electron energy loss spectrometry (EELS): Parts (a), (al), and (a2) Si53 having graphilic particles and SiOx nodules and particles, parts (b), (bl), and (b2) Si54 having graphitic nodules, and SiOx nodules and SiOx shell on the graphitic nodules.

[0046] FIG. 18D depicts high magnification TEM images: part (a) Si53 having graphitic particles and flakes, part (b) Si54 having predominately nodular morphology.

[0047] FIG. 19 is a plot of the flexural modulus of structural epoxy resin having silicon-doped three-dimensional graphene samples, according to one aspect of the present disclosure.-10- LYT IP 134.P_LYTEP322WODETAILED DESCRIPTIONDefinitions and Use of Figures

[0048] Some of the terms used in this description are defined below for easy reference. The presented terms and their respective definitions are not rigidly restricted to these definitions — a term may be further defined by the term’s use within this disclosure. The term “exemplary” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word exemplary is intended to present concepts in a concrete fashion. As used in this application and the appended claims, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or is clear from the context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A, X employs B, or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. As used herein, at least one of A or B means at least one of A, or at least one of B, or at least one of both A and B. In other words, this phrase is disjunctive. The articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or is clear from the context to be directed to a singular form.

[0049] Various aspects are described herein with reference to the figures. It should be noted that the figures are not necessarily drawn to scale, and that elements of similar structures or functions are sometimes represented by like reference characters throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the disclosed aspects — they are not representative of an exhaustive treatment of all possible aspects, and they are not intended to impute any limitation as to the scope of the claims. In addition, an illustrated aspect need not portray all aspects or advantages of usage in any particular environment.

[0050] An aspect, an advantage, or an approach described in conjunction with a particular aspect is not necessarily limited to that aspect and can be practiced in any-11- LYT IP 134.P_LYTEP322WOother aspects even if not so illustrated. References throughout this specification to “some aspects” or “other aspects” refer to a particular feature, structure, material, or characteristic described in connection with the aspects as being included in at least one aspect. Thus, the appearance of the phrases “in some aspects” “in some approaches” or “in other aspects” in various places throughout this specification are not necessarily referring to the same aspect, aspects, or approaches. The disclosed aspects are not intended to be limiting of the claims.Descriptions of Exemplary Aspects of the Invention

[0051] According to one general aspect, a composite material includes a polymer and a graphene-containing material having nodular and / or flaky morphologies. The composite material has a glass transition temperature (Tg) that is at least 3 °C higher than a glass transition temperature of the polymer in absence of the graphenecontaining material.

[0052] According to another general aspect, a composite material includes a polymer and a three-dimensional graphene. The composite material has a mechanical strength above 5 MPa at a temperature above 90 °C.

[0053] More illustrative information will now be set forth regarding various optional architectures and uses in which the foregoing method may or may not be implemented, per the desires of the user. It should be strongly noted that the following information is set forth for illustrative purposes and should not be construed as limiting in any manner. Any of the following features may be optionally incorporated with or without the exclusion of other features described.

[0054] In some aspects, carbon nanoparticles and aggregates are characterized by a high “uniformity” (i.e., high mass fraction of desired carbon allotropes), a high degree of “order” (i.e., low concentration of defects), and / or a high degree of “purity” (i.e., low concent ration of elemental impurities), in contrast to the lower uniformity, less ordered, and lower purity particles achievable with conventional systems and methods.

[0055] In some aspects, the nanoparticles produced using the methods described herein contain multi-walled spherical fullerenes (MWSFs) or connected MWSFs and-12- LYT IP 134.P_LYTEP322WOhave a high uniformity (e.g., a ratio of graphene to MWSF from 20% to 80%), a high degree of order (e.g., a Raman signature with an ID / IG ratio from 0.95 to 1.05), and a high degree of purity (e.g., the ratio of carbon to other elements (other than hydrogen) is greater than 99.9%). In some aspects, the nanoparticles produced using the methods described herein contain MWSFs or connected MWSFs, and the MWSFs do not contain a core composed of impurity elements other than carbon. In some cases, the particles produced using the methods described herein are aggregates containing the nanoparticles described above with large diameters (e.g., greater than 10 pm across).

[0056] Conventional methods have been used to produce particles containing multi-walled spherical fullerenes with a high degree of order, but the con ventional methods lead to carbon products with a variety of shortcomings. For example, high temperature synthesis techniques lead to panicles with a mixture of many carbon allotropes and therefore low uniformity (e.g., less than 20% fullerenes to other carbon allotropes) and / or small particle sizes (e.g., less than 1pm, or less than 100 nm in some cases). Methods using catalysts lead to products including the catalyst elements and therefore have low purity (e.g., less than 95% carbon to other elements) as well. These undesirable properties also often lead to undesirable electrical properties of the resulting carbon particles (e.g., electrical conductivity of less than 1000 S / m).

[0057] In some aspects, the carbon nanoparticles and aggregates described herein are characterized by Raman spectroscopy that is indicative of the high degree of order and uniformity of structure. In some aspects, the uniform, ordered and / or pure carbon nanoparticles and aggregates described herein are produced using relatively high speed, low cost improved thermal reactors and methods, as described below.Additional advantages and / or improvements will also become apparent from the following disclosure.

[0058] In the present disclosure, the term “graphene” refers to an allotrope of carbon in the form of a two-dimensional, atomic-scale, hexagonal lathee in which one atom forms each vertex. The carbon atoms in graphene are sp2-bonded. Additionally, graphene has a Raman spectrum with two main peaks: a G-mode at approximately 1580 cm'1and a D-mode at approximately 1350 cm1(when using a 532 nm excitation laser).-13- LYT IP 134.P_LYTEP322WO

[0059] In the present disclosure, the term “fullerene” refers to a molecule of carbon in the form of a hollow sphere, ellipsoid, tube, or other shapes. Spherical fullerenes can also be referred to as Buckminsterfullerenes, or buckyballs. Cylindrical fullerenes can also be referred to as carbon nanotubes. Fullerenes are similar in structure to graphite, which is composed of stacked graphene sheets of linked hexagonal rings. Fullerenes may also contain pentagonal (or sometimes heptagonal) rings.

[0060] In the present disclosure, the term “multi-walled fullerene” refers to fullerenes with multiple concentric layers. For example, multi-walled nanotubes (MWNTs) contain multiple rolled layers (concentric tubes) of graphene. Mulli-walled spherical fullerenes (MWSFs) contain mulliplc concentric spheres of fullerenes.

[0061] In the present disclosure, the term “nanoparticle” refers to a particle that measures from 1 nm to 989 nm. The nanoparticle can include one or more structural characteristics (e.g., crystal structure, defect concentration, etc.), and one or more types of atoms. The nanoparticle can be any shape, including but not limited to spherical shapes, spheroidal shapes, dumbbell shapes, cylindrical shapes, elongated cylindrical type shapes, rectangular prism shapes, disk shapes, wire shapes, irregular shapes, dense shapes (i.e., with few voids), porous shapes (i.e., with many voids), etc.

[0062] In the present disclosure, the term “aggregate” refers to a plurality of nanoparticles that are connected together by electrostatic forces (e.g., Van der Waals forces, London dispersion forces, dipole-dipole interactions, hydrogen bonding, etc.) by covalent bonds, by ionic bonds, by metallic bonds, or by other physical or chemical interactions. Aggregates can vary in size considerably, but in general are larger than about 500 nm.

[0063] In some aspects, a carbon nanoparticle, as described herein, includes two or more connected multi-walled spherical fullerenes (MWSFs) and layers of graphene coating the connected MWSFs. In some aspects, a carbon nanoparticle, as described herein, includes two or more connected multi-walled spherical fullerenes (MWSFs) and layers of graphene coating the connected MWSFs where the MWSFs do not contain a core composed of impurity elements other than carbon. In some aspects, a carbon nanoparticle, as described herein, includes two or more connected multi--14- LYT IP 134.P_LYTEP322WOwalled spherical fullerenes (MWSFs) and layers of graphene coating the connected MWSFs where the MWSFs do not contain a void (i.e., a space with no carbon atoms greater than approximately 0.5 nm, or greater than approximately 1 nm) at the center. In some aspects, the connected MWSFs are formed of concentric, well-ordered spheres of sp2-hybridized carbon atoms, as contrasted with spheres of poorly-ordered, non-uniform, amorphous carbon particles.

[0064] In some aspects, the nanoparticles containing the connected MWSFs have an average diameter in a range from 5 to 500 nm, or from 5 to 250 nm, or from 5 to 100 nm, or from 5 to 50 nm, or from 10 to 500 nm, or from 10 to 250 nm, or from 10 to 100 nm, or from 10 to 50 nm, or from 40 to 500 nm, or from 40 to 250 nm, or from 40 to 100 nm, or from 50 to 500 nm, or from 50 to 250 nm, or from 50 to 100 nm. Of course, nanoparticles containing connected MWSFs may have an average diameter characterized by having any of the foregoing values or being within any of the foregoing exemplary ranges, or an average diameter characterized by having a value or being within a range between any of the foregoing exemplary ranges, without li milalion and without departing from the scope of the presently described inventive concepts.

[0065] In some aspects, the carbon nanoparticles described herein form aggregates, wherein many nanoparticles aggregate together to form a larger unit. In some aspects, a carbon aggregate includes a plurality of carbon nanoparticles. A diameter across the carbon aggregate is in a range from 10 to 500 pm, or from 50 to 500 pm, or from 100 to 500 pm, or from 250 to 500 pm, or from 10 to 250 pm, or from 10 to 100 pm, or from 10 to 50 pm. Of course, carbon aggregates may have an average diameter characterized by having any of the foregoing values or being within any of the foregoing exemplary ranges, or an average diameter characterized by having a value or being within a range between any of the foregoing exemplary ranges, without limitation and without departing from the scope of the presently described inventive concepts.

[0066] In some aspects, the aggregate is formed from a plurality of carbon nanoparticles, as defined above. In some aspects, aggregates contain connected MWSFs. In some aspects, the aggregates contain connected MWSFs with a high uniformity metric (e.g., a ratio of graphene to MWSF from 20% to 80%), a high-15- LYT IP 134.P_LYTEP322WOdegree of order (e.g., a Raman signature with an ID / IG ratio from 0.95 to 1.05), and a high degree of purity (e.g., greater than 99.9% carbon).

[0067] One benefit of producing aggregates of carbon nanoparticles, particularly with diameters in the ranges described above, is that aggregates of particles greater than 10 pm are easier to collect than particles or aggregates of particles that are smaller than 500 nm. The ease of collection reduces the cost of manufacturing equipment used in the production of the carbon nanoparticles and increases the yield of the carbon nanoparticles. Additionally, particles greater than 10 pm in size pose fewer safety concerns compared to the risks of handling smaller nanoparticles, e.g., potential health and safety risks due to inhalation of the smaller nanoparticles. The lower health and safety risks, thus, further reduce the manufacturing cost.

[0068] In some aspects, a carbon nanoparticle has a ratio of graphene to MWSFs from 10% to 90%, or from 10% to 80%, or from 10% to 60%, or from 10% to 40%, or from 10% to 20%, or from 20% to 40%, or from 20% to 90%, or from 40% to 90%, or from 60% to 90%, or from 80% to 90%. In some aspects, a carbon aggregate has a ratio of graphene to MWSFs is from 10% to 90%, or from 10% to 80%, or from 10% to 60%, or from 10% to 40%, or from 10% to 20%, or from 20% to 40%, or from 20% to 90%, or from 40% to 90%, or from 60% to 90%, or from 80% to 90%. Of course, carbon nanoparticles may have a graphene-to-MWSF ratio characterized by having any of the foregoing values or being within any of the foregoing exemplary ranges, or an average graphene-to-MWSF ratio characterized by having a value or being within a range between any of the foregoing exemplary ranges, without li milalion and without departing from the scope of the presently described inventive concepts.

[0069] In some aspects, a carbon nanoparticle has a ratio of graphene to connected MWSFs from 10% to 90%, or from 10% to 80%, or from 10% to 60%, or from 10% to 40%, or from 10% to 20%, or from 20% to 40%, or from 20% to 90%, or from 40% to 90%, or from 60% to 90%, or from 80% to 90%. In some aspects, a carbon aggregate has a ratio of graphene to connected MWSFs is from 10% to 90%, or from 10% to 80%, or from 10% to 60%, or from 10% to 40%, or from 10% to 20%, or from 20% to 40%, or from 20% to 90%, or from 40% to 90%, or from 60% to 90%, or from 80% to 90%. Of course, carbon nanoparticles may have a graphene--16- LYT IP 134.P_LYTEP322WOto-connected MWSF ratio characterized by having any of the foregoing values or being within any of the foregoing exemplary ranges, or an average graphene-to-connected MWSF ratio characterized by having a value or being within a range between any of the foregoing exemplary ranges, without limitation and without departing from the scope of the presently described inventive concepts.

[0070] In some aspects, Raman spectroscopy is used to characterize carbon allotropes to distinguish their molecular structures. For example, graphene can be characterized using Raman spectroscopy to determine information such as order / disorder, edge and grain boundaries, thickness, number of layers, doping, strain, and thermal conductivity. MWSFs have also been characterized using Raman spectroscopy to determine the degree of order of the MWSFs.

[0071] In some aspects, Raman spectroscopy is used to characterize the structure of MWSFs or connected MWSFs. The main peaks in the Raman spectra are the G-mode and the D-mode. The G-mode is attributed to the vibration of carbon atoms in sp2-hybridized carbon networks, and the D-mode is related to the breathing of hexagonal carbon rings with defects. In some cases, defects may be present yet may not be detectable in the Raman spectra. For example, if the presented crystalline structure is orthogonal with respect to the basal plane, the D-peak will show an increase. On the other hand, if presented with a perfectly planar surface that is parallel with respect to the basal plane, the D-peak will be zero.

[0072] When using 532 nm incident light, the Raman G-mode is typically at 1582 cm1for planar graphite, however, can be downshifted for MWSFs or connected MWSFs (e.g., down to 1565cm1or down tol580 cin ' j. The D-mode is observed at approximately 1350 cm1in the Raman spectra of MWSFs or connected MWSFs. The ratio of the intensities of the D-mode peak to G-mode peak (i.e., the ID / IG) is related to the degree of order of the MWSFs, where a lower ID / IG indicates a higher degree of order. An ID / IG near or below 1 indicates a relatively high degree of order, and an ID / IG greater than 1.1 indicates a lower degree of order.

[0073] In some aspects, a carbon nanoparticle or a carbon aggregate containing MWSFs or connected MWSFs, as described herein, has a Raman spectrum with a first Raman peak at about 1350 cm'1and a second Raman peak at about 1580 cm'1when-17- LYT IP 134.P_LYTEP322WOusing 532 nm incident light. In some aspects, the ratio of an intensity of the first Raman peak to an intensity of the second Raman peak (i.e., the ID / IG) for the nanoparticles or the aggregates described herein is in a range from 0.95 to 1.05, or from 0.9 to 1.1, or from 0.8 to 1.2, or from 0.9 to 1.2, or from 0.8 to 1.1, or from 0.5 to 1.5, or less than 1.5, or less than 1.2, or less than 1.1, or less than 1, or less than 0.95, or less than 0.9, or less than 0.8. Of course, carbon nanoparticles or aggregates including MWSFs or connected MWSFs may be characterized by a ratio of first and second Raman peak intensities having any of the foregoing values or being within any of the foregoing exemplary ranges, or a ratio of first and second Raman peak intensities characterized by having a value or being within a range between any of the foregoing exemplary ranges, without limitation and without departing from the scope of the presently described inventive concepts.

[0074] In some aspects, a carbon aggregate containing MWSFs or connected MWSFs, as defined above, has a high purity. In some aspects, the carbon aggregate containing MWSFs or connected MWSFs has a ratio of carbon to metals of greater than 99.99%, or greater than 99.95%, or greater than 99.9%, or greater than 99.8%, or greater than 99.5%, or greater than 99%. In some aspects, the carbon aggregate has a ratio of carbon to other elements of greater than 99.99%, or greater than 99.95%, or greater than 99.9%, or greater than 99.5%, or greater than 99%, or greater than 90%, or greater than 80%, or greater than 70%, or greater than 60%. In some aspects, the carbon aggregate has a ratio of carbon to other elements (except for hydrogen) of greater than 99.99%, or greater than 99.95%, or greater than 99.9%, or greater than 99.8%, or greater than 99.5%, or greater than 99%, or greater than 90%, or greater than 80%, or greater than 70%, or greater than 60%. Of course, carbon aggregates including MWSFs or connected MWSFs may be characterized by a ratio of carbon to metal having any of the foregoing values or being within any of the foregoing exemplary ranges, or a ratio of carbon to metal having value or being within a range between any of the foregoing exemplary ranges, without limitation and without departing from the scope of the presently described inventive concepts.

[0075] In some aspects, a carbon aggregate containing MWSFs or connected MWSFs, as defined above, has a high specific surface area. In some aspects, the carbon aggregate has a Brunauer, Emmett and Teller (BET) specific surface area from-18- LYT IP 134.P_LYTEP322WO10 to 200 m2 / g, or from 10 to 100 m2 / g, or from 10 to 50 m2 / g, or from 50 to 200 m2 / g, or from 50 to 100 m2 / g, or from 10 to 1000 m2 / g. Of course, carbon aggregates including MWSFs or connected MWSFs may be characterized by a BET specific surface area having any of the foregoing values or being within any of the foregoing exemplary ranges, or a BET specific surface area characterized by having a value or being within a range between any of the foregoing exemplary ranges, without li milalion and without departing from the scope of the presently described inventive concepts.

[0076] In some aspects, a carbon aggregate containing MWSFs or connected MWSFs, as defined above, has a high electrical conductivity. In some aspects, a carbon aggregate containing MWSFs or connected MWSFs, as defined above, is compressed into a pellet and the pellet has an electrical conductivity greater than 500 S / m, or greater than 1000 S / m, or greater than 2000 S / m, or greater than 3000 S / m, or greater than 4000 S / m, or greater than 5000 S / m, or greater than 10000 S / m, or greater than 20000 S / m, or greater than 30000 S / m, or greater than 40000 S / m, or greater than 50000 S / m, or greater than 60000 S / m, or greater than 70000 S / m, or from 500 S / m to 100000 S / m, or from 500 S / m to 1000 S / m, or from 500 S / m to 10000 S / m, or from 500 S / m to 20000 S / m, or from 500 S / m to 100000 S / m, or from 1000 S / m to 10000 S / m, or from 1000 S / m to 20000 S / m, or from 10000 to 100000 S / m, or from 10000 S / m to 80000 S / m, or from 500 S / m to 10000 S / m. Of course, carbon aggregates including MWSFs or connected MWSFs may be characterized by an electrical conductivity having any of the foregoing values or being within any of the foregoing exemplary ranges, or an electrical conductivity characterized by having a value or being within a range between any of the foregoing exemplary ranges, without 11 milalion and without departing from the scope of the presently described inventive concepts.

[0077] In some cases, the density of the pellet is approximately 1 g / cm3, or approximately 1.2 g / cm3, or approximately 1.5 g / cm3, or approximately 2 g / cm3, or approximately 2.2 g / cm3, or approximately 2.5 g / cm3, or approximately 3 g / cm3. Of course, pellets may be characterized by a density having any of the foregoing values or being within any of the foregoing exemplary ranges, or a density having a value or being within a range between any of the foregoing exemplary ranges, without-19- LYT IP 134.P_LYTEP322WOlimitation and without departing from the scope of the presently described inventive concepts.

[0078] Additionally, tests have been performed in which compressed pellets of the carbon aggregate materials have been formed with compressions of 2000 psi and 12000 psi and with annealing temperatures of 800°C and 1000°C. The higher compression and / or the higher annealing temperatures generally result in pellets with a higher degree of electrical conductivity, including in the range of 12410.0 S / m to 13173.3 S / m.HIGH PURITY CARBON ALLOTROPES PRODUCED USING THERMAL PROCESSING SYSTEMS

[0079] In some aspects, the carbon nanoparticles and aggregates described herein are produced using thermal reactors and methods, such as any appropriate thermal reactor and / or method. Further details pertaining to thermal reactors and / or methods of use can be found in U.S. Patent No. 9,862,602, issued January 9, 2018, titled “CRACKING OF A PROCESS GAS,” which is hereby incorporated by reference in its entirety. Additionally, precursors (e.g., including methane, ethane, propane, butane, and natural gas) can be used with the thermal reactors to produce the carbon nanoparticles and the carbon aggregates described herein.

[0080] In some aspects, the carbon nanoparticles and aggregates described herein are produced using the thermal reactors with gas flow rates from 1 slm to 10 slm, or from 0.1 slm to 20 slm, or from 1 slm to 5 slm, or from 5 slm to 10 slm, or greater than 1 slm, or greater than 5 slm. In some aspects, the carbon nanoparticles and aggregates described herein are produced using the thermal reactors with gas residence times from 0.1 seconds to 30 seconds, or from 0.1 seconds to 10 seconds, or from 1 seconds to 10 seconds, or from 1 seconds to 5 seconds, from 5 seconds to 10 seconds, or greater than 0.1 seconds, or greater than 1 seconds, or greater than 5 seconds, or less than 30 seconds. Of course, carbon nanoparticles and aggregates may be produced using thermal reactors with gas flow rates having any of the foregoing values or being within any of the foregoing exemplary ranges, or gas flow rates having a value or being within a range between any of the foregoing exemplary-20- LYT IP 134.P_LYTEP322WOranges, without limitation and without departing from the scope of the presently described inventive concepts.

[0081] In some aspects, the carbon nanoparticles and aggregates described herein are produced using the thermal reactors with production rates from 10 g / hr to 200 g / hr, or from 30 g / hr to 200 g / hr, or from 30 g / hr to 100 g / hr, or from 30 g / hr to 60 g / hr, or from 10 g / hr to 100 g / hr, or greater than 10 g / hr, or greater than 30 g / hr, or greater than 100 g / hr. Of course, carbon nanoparticles and aggregates may be produced using thermal reactors with production rates having any of the foregoing values or being within any of the foregoing exemplary ranges, or production rates having a value or being within a range between any of the foregoing exemplary ranges, without limilalion and without departing from the scope of the presently described inventive concepts.

[0082] In some aspects, thermal reactors or other cracking apparatuses and thermal reactor methods or other cracking methods can be used for refining, pyrolyzing, dissociating or cracking feedstock process gases into its constituents to produce the carbon nanoparticles and the carbon aggregates described herein, as well as other solid and / or gaseous products (e.g., hydrogen gas and / or lower order hydrocarbon gases). The feedstock process gases generally include, for example, hydrogen gas (H2), carbon dioxide (CO2), Ci to C10 hydrocarbons, aromatic hydrocarbons, and / or other hydrocarbon gases such as natural gas, methane, ethane, propane, butane, isobutane, saturated / unsaturated hydrocarbon gases, ethene, propene, etc., and mixtures thereof. The carbon nanoparticles and the carbon aggregates can include, for example, multi-walled spherical fullerenes (MWSFs), connected MWSFs, carbon nanospheres, graphene, graphite, highly ordered pyrolytic graphite, singlewalled nanotubes, multi-walled nanotubes, other solid carbon products, and / or the carbon nanoparticles and the carbon aggregates described herein.

[0083] Some aspects for producing the carbon nanoparticles and the carbon aggregates described herein include thermal cracking methods that use, for example, an elongated longitudinal heating element optionally enclosed within an elongated casing, housing or body of a thermal cracking apparatus. The body generally includes, for example, one or more tubes or other appropriate enclosures made of stainless steel, titanium, graphite, quartz, or the like. In some aspects, the body of the thermal-21- LYT IP 134.P_LYTEP322WOcracking apparatus is generally cylindrical in shape with a central elongate longitudinal axis arranged vertically and a feedstock process gas inlet at or near a top of the body. The feedstock process gas flows longitudinally down through the body or a portion thereof. In the vertical configuration, both gas flow and gravity assist in the removal of the solid products from the body of the thermal cracking apparatus.

[0084] The heating element generally includes, for example, a heating lamp, one or more resistive wires or filaments (or twisted wires), metal filaments, metallic strips or rods, and / or other appropriate thermal radical generators or elements that can be heated to a specific temperature (i.e., a molecular cracking temperature) sufficient to thermally crack molecules of the feedstock process gas. The heating element is generally disposed, located or arranged to extend centrally within the body of the thermal cracking apparatus along the central longitudinal axis thereof. For example, if there is only one heating element, then it is placed at or concentric with the central longitudinal axis, and if there is a plurality of the heating elements, then they are spaced or offset generally symmetrically or concentrically at locations near and around and parallel to the central longitudinal axis.

[0085] Thermal cracking to produce the carbon nanoparticles and aggregates described herein is generally achieved by passing the feedstock process gas over, or in contact with, or within the vicinity of, the heating element within a longitudinal elongated reaction zone generated by heat from the heating element and defined by and contained inside the body of the thermal cracking apparatus to heat the feedstock process gas to or at a specific molecular cracking temperature.

[0086] The reaction zone is considered to be the region surrounding the heating element and close enough to the healing element for the feedstock process gas to receive sufficient heat to thermally crack the molecules thereof. The reaction zone is thus generally axially aligned or concentric with the central longitudinal axis of the body. In some aspects, the thermal cracking is performed under a specific pressure. In some aspects, the feedstock process gas is circulated around or across the outside surface of a container of the reaction zone or a heating chamber in order to cool the container or chamber and preheat the feedstock process gas before flowing the feedstock process gas into the reaction zone.-22- LYT IP 134.P_LYTEP322WO

[0087] In some aspects, the carbon nanoparticles and aggregates described herein and / or hydrogen gas are produced without the use of catalysts. In other words, the process is catalyst free.

[0088] Some aspects to produce the carbon nanoparticles and aggregates described herein using thermal cracking apparatuses and methods to provide a standalone system that can advantageously be rapidly scaled up or scaled down for different production levels as desired. For example, some aspects are scalable to provide a standalone hydrogen and / or carbon nanoparticle producing station, a hydrocarbon source, or a fuel cell station. Some aspects can be scaled up to provide higher capacity systems, e.g., for a refinery or the like.

[0089] In some aspects, a thermal cracking apparatus for cracking a feedstock process gas to produce the carbon nanoparticles and aggregates described herein include a body, a feedstock process gas inlet, and an elongated head ng element. The body has an inner volume with a longitudinal axis. The inner volume has a reaction zone concentric with the longitudinal axis. A feedstock process gas is flowed into the inner volume through the feedstock process gas inlet during thermal cracking operations. The elongated heating element is disposed within the inner volume along the longitudinal axis and is surrounded by the reaction zone. During the thermal cracking operations, the elongated heating element is heated by electrical power to a molecular cracking temperature to generate the reaction zone, the feedstock process gas is heated by heat from the elongated heating element, and the heat thermally cracks molecules of the feedstock process gas that are within the reaction zone into constituents of the molecules.

[0090] In some aspects, a method for cracking a feedstock process gas to produce the carbon nanoparticles and aggregates described herein includes: (1) providing a thermal cracking apparatus having an inner volume that has a longitudinal axis and an elongated heating element disposed within the inner volume along the longitudinal axis; (2) heating the elongated heating element by electrical power to a molecular cracking temperature to generate a longitudinal elongated reaction zone within the inner volume; (3) flowing a feedstock process gas into the inner volume and through the longitudinal elongated reaction zone (e.g., wherein the feedstock process gas is heated by heat from the elongated heating element); and (4) thermally cracking-23- LYT IP 134.P_LYTEP322WOmolecules of the feedstock process gas within the longitudinal elongated reaction zone into constituents thereof (e.g., hydrogen gas and one or more solid products) as the feedstock process gas flows through the longitudinal elongated reaction zone.

[0091] In some aspects, the feedstock process gas to produce the carbon nanoparticles and aggregates described herein includes a hydrocarbon gas. The results of cracking include hydrogen (e.g., H2) and various forms of the carbon nanoparticles and aggregates described herein. In some aspects, the carbon nanoparticles and aggregates include two or more MWSFs and layers of graphene coating the MWSFs, and / or connected MWSFs and layers of graphene coating the connected MWSFs. In some aspects, the feedstock process gas is preheated (e.g., to 100°C to 500°C) by flowing the feedstock process gas through a gas prehcaling region between a heating chamber and a shell of the thermal cracking apparatus before flowing the feedstock process gas into the inner volume. In some aspects, a gas having nanoparticles therein is flowed into the inner volume and through the longitudinal elongated reaction zone to mix with the feedstock process gas, and a coating of a solid product (e.g., layers of graphene) is formed around the nanoparticles.POST-PROCESSING HIGH PURITY STRUCTURED CARBONS

[0092] In some aspects, the carbon nanoparticles and aggregates containing multiwalled spherical fullerenes (MWSFs) or connected MWSFs described herein are produced and collected, and no post-processing is done. In other aspects, the carbon nanoparticles and aggregates containing multi-walled spherical fullerenes (MWSFs) or connected MWSFs described herein are produced and collected, and some postprocessing is done. Some examples of post-processing involved in the present disclosure include mechanical processing such as ball milling, grinding, attrition milling, micro fluidizing, and other techniques to reduce the particle size without damaging the MWSFs. Some further examples of post-processing include exfoliation processes such as sheer mixing, chemical etching, oxidizing (e.g., Hummer method), thermal annealing, doping by adding elements during annealing (e.g., sulfur, nitrogen), steaming, filtering, and lyophilizing, among others. Some examples of postprocessing include sintering processes such as spark plasma sintering (SPS), direct current sintering, microwave sintering, and ultraviolet (UV) sintering, which can be conducted at high pressure and temperature in an inert gas. In some aspects, multiple-24- LYT IP 134.P_LYTEP322WOpost-processing methods can be used together or in a series. In some aspects, the postprocessing produces functionalized carbon nanoparticles or aggregates containing multi-walled spherical fullerenes (MWSFs) or connected MWSFs.

[0093] In some aspects, the materials are mixed together in different combinations. In some aspects, different carbon nanoparticles and aggregates containing MWSFs or connected MWSFs described herein are mixed together before post-processing. For example, different carbon nanoparticles and aggregates containing MWSFs or connected MWSFs with different properties (e.g., different sizes, different compositions, different purities, from different processing runs, etc.) can be mixed together. In some aspects, the carbon nanoparticles and aggregates containing MWSFs or connected MWSFs described herein can be mixed with graphene to change the ratio of the connected MWSFs to graphene in the mixture. In some aspects, different carbon nanoparticles and aggregates containing MWSFs or connected MWSFs described herein can be mixed together after post-processing. For example, different carbon nanoparticles and aggregates containing MWSFs or connected MWSFs with different properties and / or different post-processing methods (e.g., different sizes, different compositions, different functionality, different surface properties, different surface areas) can be mixed together.

[0094] In some aspects, the carbon nanoparticles and aggregates described herein are produced and collected, and subsequently processed by mechanical grinding, milling, and / or exfoliating. In some aspects, the processing (e.g., by mechanical grinding, milling, exfoliating, etc.) reduces the average size of the particles. In some aspects, the processing (e.g., by mechanical grinding, milling, exfoliating, etc.) increases the average surface area of the particles. In some aspects, the processing by mechanical grinding, milling and / or exfoliation shears off some fraction of the carbon layers, producing sheets of graphite mixed with the carbon nanoparticles.

[0095] In some aspects, the mechanical grinding or milling is performed using a ball mill, a planetary mill, a rod mill, a shear mixer, a high-shear granulator, an autogenous mill, or other types of machining used to break solid materials into smaller pieces by grinding, crushing or cutting. In some aspects, the mechanical grinding, milling and / or exfoliating is performed wet or dry. In some aspects, the mechanical grinding is performed by grinding for some period of time, then idling for-25- LYT IP 134.P_LYTEP322WOsome period of time, and repeating the grinding and idling for a number of cycles. In some aspects, the grinding period is from 1 minute to 20 minutes, or from 1 minute to 10 minutes, or from 3 minutes to 8 minutes, or approximately 3 minutes, or approximately 8 minutes. In some aspects, the idling period is from 1 minute to 10 minutes, or approximately 5 minutes, or approximately 6 minutes. In some aspects, the number of grinding and idling cycles is from 1 minute to 100 minutes, or from 5 minutes to 100 minutes, or from 10 minutes to 100 minutes, or from 5 minutes to 10 minutes, or from 5 minutes to 20 minutes. In some aspects, the total amount of time of grinding and idling is from 10 minutes to 1200 minutes, or from 10 minutes to 600 minutes, or from 10 minutes to 240 minutes, or from 10 minutes to 120 minutes, or from 100 minutes to 90 minutes, or from 10 minutes to 60 minutes, or approximately 90 minutes, or approximately 120 minutes. Of course, grinding, milling, or idling limes within the scope of the presently disclosed i nvenli vc aspects may have any of the foregoing values or be within any of the foregoing exemplary ranges, between any of the foregoing exemplary ranges, without limitation and without departing from the scope of the presently described inventive concepts.

[0096] In some aspects, the grinding steps in the cycle are performed by rotating a mill in one direction for a first cycle (e.g., clockwise) and then rotating a mill in the opposite direction (e.g., counterclockwise) for the next cycle. In some aspects, the mechanical grinding or milling is performed using a ball mill, and the grinding steps are performed using a rotation speed from 100 to 1000 rpm, or from 100 to 500 rpm, or approximately 400 rpm, or any value or range of values therebetween. In some aspects, the mechanical grinding or milling is performed using a ball mill that uses a milling media with a diameter from 0.1 mm to 20 mm, or from 0.1 mm to 10 mm, or from 1 mm to 10 mm, or approximately 0.1 mm, or approximately 1 mm, or approximately 10 mm, or any value or range of values therebetween. In some aspects, the mechanical grinding or milling is performed using a ball mill that uses a milling media composed of metal such as steel, an oxide such as zirconium oxide (zirconia), yttria stabilized zirconium oxide, silica, alumina, magnesium oxide, or other hard materials such as silicon carbide or tungsten carbide.

[0097] In some aspects, the carbon nanoparticles and aggregates described herein are produced and collected and subsequently processed using elevated temperatures-26- LYT IP 134.P_LYTEP322WOsuch as thermal annealing or sintering. In some aspects, the processing using elevated temperatures is done in an inert environment such as nitrogen or argon. In some aspects, the processing using elevated temperatures is done at atmospheric pressure, or under vacuum, or at low pressure. In some aspects, the processing using elevated temperatures is done at a temperature from 500°C to 2500°C, or from 500°C to 1500°C, or from 800°C to 1500°C, or from 800°C to 1200°C, or from 800°C to 1000°C, or from 2000°C to 2400°C, or approximately 800°C, or approximately 1000°C, or approximately 1500°C, or approximately 2000°C, or approximately 2400°C. Of course, processing using elevated temperatures may be performed at any of the foregoing temperatures, or at a temperature within any of the foregoing exemplary ranges, or between any of the foregoing exemplary ranges, without li milalion and without departing from the scope of the presently described inventive concepts.

[0098] In some aspects, the carbon nanoparticles and aggregates described herein are produced and collected, and subsequently, in post processing steps, additional elements or compounds are added to the carbon nanoparticles, thereby incorporating the unique properties of the carbon nanoparticles and aggregates into other mixtures of materials.

[0099] In some aspects, either before or after post-processing, the carbon nanoparticles and aggregates described herein are added to solids, liquids or slurries of other elements or compounds to form additional mixtures of materials incorporating the unique properties of the carbon nanoparticles and aggregates. In some aspects, the carbon nanoparticles and aggregates described herein are mixed with other solid particles, polymers or other materials.

[0100] In some aspects, either before or after post-processing, the carbon nanoparticles and aggregates described herein are used in various applications beyond applications pertaining to the present disclosure. Such applications including but not limited to transportation applications (e.g., automobile and truck Ores, couplings, mounts, elastomeric o-rings, hoses, sealants, grommets, etc.) and industrial applications (e.g., rubber additives, functionalized addi lives for polymeric materials, additives for epoxies, etc.).-27- LYT IP 134.P_LYTEP322WO

[0101] FIG. 1A and IB show transmission electron microscope (TEM) images of as-synthesized carbon nanoparticles. The carbon nanoparticles of FIG. 1A (at a first magnification) and FIG. IB (at a second magnification) contain connected mulli-walled spherical fullerenes 102 (MWSFs) with graphene layers 104 that coat the connected MWSFs. The ratio of MWSF to graphene allotropes in this example is approximately 80% due to the relatively short residence times. The MWSFs in FIG.1A are approximately 5 nm to 10 nm in diameter, and the diameter can be from 5 nm to 500 nm using the conditions described above. In some aspects, the average diameter across the MWSFs is in a range from 5 nm to 500 nm, or from 5 nm to 250 nm, or from 5 nm to 100 nm, or from 5 nm to 50 nm, or from 10 nm to 500 nm, or from 10 nm to 250 nm, or from 10 nm to 100 nm, or from 10 nm to 50 nm, or from 40 nm to 500 nm, or from 40 nm to 250 nm, or from 40 nm to 100 nm, or from 50 nm to 500 nm, or from 50 nm to 250 nm, or from 50 nm to 100 nm. Of course, average MWSF diameter within the scope of the presently disclosed inventive aspects may have any of the foregoing values or be within any of the foregoing exemplary ranges, or between any of the foregoing exemplary ranges, without limitation and without departing from the scope of the presently described inventive concepts. No catalyst was used in this process, and therefore, there is no central seed containing contaminants. The aggregate particles produced in this example had a particle size of approximately 10 pm to 100 pm, or approximately 10 pm to 500 pm.

[0102] FIG. 1C shows the Raman spectrum of the as-synthesized aggregates in this example taken with 532 nm incident light. The ID / IG for the aggregates produced in this example is from approximately 0.99 to 1.03, indicating that the aggregates were composed of carbon allotropes with a high degree of order.

[0103] FIG. ID and FIG. IE show example TEM images of the carbon nanoparticles after size reduction by grinding in a ball mill. The ball milling was performed in cycles with a 3 minute counterclockwise grinding step, followed by a 6 minute idle step, followed by a 3 minute clockwise grinding step, followed by a 6 minute idle step. The grinding steps were performed using a rotation speed of 400 rpm. The milling media was zirconia and ranged in size from 0.1 mm to 10 mm. The total size reduction processing time was from 60 minutes to 120 minutes. After size reduction, the aggregate particles produced in this example had a particle size of-28- LYT IP 134.P_LYTEP322WOapproximately 1 pm to 5 pm. The carbon nanoparticles after size reduction are connected MWSFs with layers of graphene coating the connected MWSFs.

[0104] FIG. IF shows a Raman spectrum from these aggregates after size reduction taken with a 532 nm incident light. The ID / IG for the aggregate panicles in this example after size reduction is approximately 1.04. Additionally, the particles after size reduction had a Brunauer, Emmett and Teller (BET) specific surface area of approximately 40 m2 / g to 50 m2 / g.

[0105] The purity of the aggregates produced in this sample were measured using mass spectrometry and x-ray fluorescence (XRF) spectroscopy. The ratio of carbon to other elements, except for hydrogen, measured in 16 different batches was from 99.86% to 99.98%, with an average of 99.94% carbon.

[0106] In this example, carbon nanoparticles were generated using a thermal hotwire processing system. The precursor material was methane, which was flowed from 1 slm to 5 slm. With these flow rates and the tool geometry, the residence time of the gas in the reaction chamber was from approximately 20 second to 30 seconds, and the carbon particle production rate was from approximately 20 g / hr.

[0107] Further details pertaining to such a processing system can be found in the previously mentioned U.S. Patent 9,862,602, tilled “CRACKING OF A PROCESS GAS.”

[0108] FIG. 1G, FIG. 1H and FIG. II show TEM images of as-synthesized carbon nanoparticles of this example. The carbon nanoparticles contain connected multi-walled spherical fullerenes (MWSFs) with layers of graphene coaling the connected MWSFs. The ratio of multi-walled fullerenes to graphene allotropes in this example is approximately 30% due to the relatively long residence times allowing thicker, or more, layers of graphene to coat the MWSFs. No catalyst was used in this process, and therefore, there is no central seed containing contaminants. The as-synthesized aggregate particles produced in this example had particle sizes of approximately 10 pm to 500 pm. FIG. 1J shows a Raman spectrum from the aggregates of this example. The Raman signature of the as-synthesized particles in this example is indicali vc of the thicker graphene layers which coat the MWSFs in the-29- LYT IP 134.P_LYTEP322WOas-synthesized material. Additionally, the as- synthesized particles had a Brunauer, Emmett and Teller (BET) specific surface area of approximately 90 m2 / g to 100 m2 / g.

[0109] FIG. IK and FIG. IL show TEM images of the carbon nanoparticles of this example. Specifically, the images depict the carbon nanoparticles after performance of size reduction by grinding in a ball mill. The size reduction process conditions were the same as those described as pertains to the foregoing FIG. 1G through FIG. 1J. After size reduction, the aggregate particles produced in this example had a particle size of approximately 1 pm to 5 pm. The TEM images show that the connected MWSFs that were buried in the graphene coating can be observed after size reduction. FIG. IM shows a Raman spectrum from the aggregates of this example after size reduction taken with 532 nm incident light. The ID / IG for the aggregate particles in this example after size reduction is approximately 1, indicating that the connected MWSFs that were buried in the graphene coating as-synthesized had become detectable in Raman after size reduction, and were well ordered. The particles after size reduction had a Brunauer, Emmett and Teller (BET) specific surface area of approximately 90 m2 / g to 100 m2 / g.

[0110] FIG. IN is a scanning electron microscope (SEM) image of carbon aggregates showing the graphite and graphene allotropes at a first magnification. FIG.10 is a SEM image of carbon aggregates showing the graphite and graphene allotropes at a second magnification. The layered graphene is clearly shown within the distortion (wrinkles) of the carbon. The 3D structure of the carbon allotropes is also visible.

[0111] The particle size distribution of the carbon particles of FIG. IN and FIG.10 is shown in FIG. IP. The mass basis cumulative particle size distribution 106 corresponds to the left y-axis in the graph (Q3(x) [%]). The histogram of the mass particle size distribution 108 corresponds to the right axis in the graph (dQ3(x) [%]). The median particle size is approximately 33 pm. The 10th percentile particle size is approximately 9 pm, and the 90th percentile particle size is approximately 103 pm. The mass density of the particles is approximately 10 g / L.

[0112] The particle size distribution of the carbon particles captured from a multiple-stage reactor is shown in FIG. IQ. The mass basis cumulative particle size-30- LYT IP 134.P_LYTEP322WOdistribution 114 corresponds to the left y-axis in the graph (Q3(x) [%]). The histogram of the mass particle size distribution 116 corresponds to the right axis in the graph (dQ3(x) [%]). The median particle size captured is approximately 11 pm. The 10th percentile particle size is approximately 3.5 pm, and the 90th percentile particle size is approximately 21 pm. The graph in FIG. IQ also shows the number basis cumulative particle size distribution 118 corresponding to the left y-axis in the graph (Q°(x) [%]). The median particle size by number basis is from approximately 0.1 pm to approximately 0.2 pm. The mass density of the particles collected is approximately 22 g / L.

[0113] Returning to the discussion of FIG. IP, the graph also shows a second set of example results. Specifically, in this example, the particles were size -reduced by mechanical grinding, and then the size -reduced particles were processed using a cyclone separator. The mass basis cumulative particle size distribution 110 of the size -reduced carbon particles captured in this example corresponds to the left y-axis in the graph (Q3(x) [%]). The histogram of the mass basis particle size distribution 112 corresponds to the right axis in the graph (dQ3(x) [%]). The median particle size of the size -reduced carbon particles captured in this example is approximately 6 pm. The 10th percentile particle size is from 1 pm to 2 pm, and the 90th percentile particle size is from 10 pm to 20 pm.

[0114] Further details pertaining to making and using cyclone separators can be found in U.S. Patent Application 15 / 725,928, filed October 5, 2017, titled “MICROWAVE REACTOR SYSTEM WITH GAS-SOLIDS SEPARATION”, which is hereby incorporated by reference in its entirety.HIGH PURITY CARBON ALLOTROPES PRODUCED USING MICROWAVE REACTOR SYSTEMS

[0115] In some cases, carbon particles and aggregates containing graphite, graphene and amorphous carbon can be generated using a microwave plasma reactor system using a precursor material that contains methane, or contains isopropyl alcohol (IP A), or contains ethanol, or contains a condensed hydrocarbon (e.g., hexane). In some other examples, the carbon-containing precursors are optionally mixed with a supply gas (e.g., argon). The particles produced in this example contained graphite,-31- LYT IP 134.P_LYTEP322WOgraphene, amorphous carbon and no seed panicles. The particles in this example had a ratio of carbon to other elements (other than hydrogen) of approximately 99.5% or greater.

[0116] In one particular example, a hydrocarbon was the input material for the microwave plasma reactor, and the separated outputs of the reactor comprised hydrogen gas and carbon particles containing graphite, graphene and amorphous carbon. The carbon particles were separated from the hydrogen gas in a multi-stage gas-solid separation system. The solids loading of the separated outputs from the reactor was from 0.001 g / L to 2.5 g / L.

[0117] FIG. 1R, FIG. IS, and FIG. IT are TEM images of as-synthesized carbon nanoparticles. The images show examples of graphite, graphene and amorphous carbon allotropes. The layers of graphene and other carbon materials can be clearly seen in the images.

[0118] The particle size distribution of the carbon particles captured is shown in FIG. 1U. The mass basis cumulative particle size distribution 120 corresponds to the left y-axis in the graph (Q3(x) [%]). The histogram of the mass particle size distribution 122 corresponds to the right axis in the graph (dQ3(x) [%]). The median particle size captured in the cyclone separator in this example was approximately 14 pm. The 10th percentile particle size was approximately 5 pm, and the 90th percentile particle size was approximately 28 pm. The graph in FIG. 1U also shows the number basis cumulative particle size distribution 124 corresponding to the left y-axis in the graph (Q°(x) [%]). The median particle size by number basis in this example was from approximately 0.1 pm to approximately 0.2 pm.

[0119] FIG. IV, FIG. 1W, and FIG. IX, and 1Y are images that show three-dimensional carbon-containing structures that are grown onto other three-dimensional structures. FIG. IV is a 100X magnification of three-dimensional carbon structures grown onto carbon fibers, whereas FIG. 1W is a 200X magni licalion of three-dimensional carbon structures grown onto carbon fibers. FIG. IX is a 10000X magnification of three-dimensional carbon structures grown onto carbon fibers. The three-dimensional carbon growth over the fiber surface is shown. FIG. 1Y is a-32- LYT IP 134.P_LYTEP322WO10000X magnification of three-dimensional carbon structures grown onto carbon fibers. The image depicts growth onto the basal plane as well as onto edge planes.

[0120] More specifically, FIGs. 1V-1Y show example SEM images of 3D carbon materials grown onto fibers using plasma energy from a microwave plasma reactor as well as thermal energy from a thermal reactor. FIG. IV shows an SEM image of intersecting fibers 131 and 132 with 3D carbon material 130 grown on the surface of the fibers. FIG. 1W is a higher magnification image (the scale bar is 300 pm compared to 500 pm for FIG. IV) showing 3D carbon growth 130 on the fiber 132.FIG. IX is a further magnified view (scale bar is 40 pm) showing 3D carbon growth 130 on fiber surface 135, where the 3D nature of the carbon growth 130 can be clearly seen. FIG. 1Y shows a close-up view (scale bar is 500 nm) of the carbon alone, showing interconnection between basal planes 136 and edge planes 134 of numerous sub-particles of the 3D carbon material grown on the fiber. FIGs. 1V-1Y demonstrate the ability to grow 3D carbon on a 3D fiber structure according to some aspects, such as 3D carbon growth grown on a 3D carbon fiber.

[0121] In some aspects, 3D carbon growth on fibers can be achieved by introducing a plurality of fibers into the microwave plasma reactor and using plasma in the microwave reactor to etch the fibers. The etching creates nucleation sites such that when carbon particles and sub-particles are created by hydrocarbon disassociation in the reactor, growth of 3D carbon structures is initiated at these nucleation sites. The direct growth of the 3D carbon structures on the fibers, which themselves are three-dimensional in nature, provides a highly integrated, 3D structure with pores into which resin can permeate. This 3D reinforcement matrix (including the 3D carbon structures integrated with high aspect ratio reinforcing fibers) for a resin composite results in enhanced material properties, such as tensile strength and shear, compared to composites with conventional fibers that have smooth surfaces and which smooth surfaces typically delaminate from the resin matrix.

[0122] Graphene is an allotrope of sp2-hybridized carbon arranged in a honeycomb lattice nanostructure possessing a significantly higher mechanical strength than steel. There is a desire to include graphene in thermoset epoxy polymers (e.g., structural epoxy, epoxy adhesive, etc.). According to one aspect, silicon-doped 3D graphene in epoxy polymer increases mechanical properties of the polymer for better-33- LYT IP 134.P_LYTEP322WOdurability and performance. Various aspects herein describe a 3D graphene (3DG) functionalized with silicon, silicon and nitrogen, etc.

[0123] 3DG particles a structural morphology that is fundamentally different than 2D graphene. 3DG may be characterized as a carbon nanoparticle. In preferred approaches, as described herein, the carbon nanoparticles have a structural morphology that may be characterized by a plurality of spikes, nodules, and / or flakes. The carbon nanoparticle as described herein includes two or more connected multiwalled spherical fullerenes and layers of graphene coating the connected multi-walled spherical fullerenes. Preferably, the multi-walled spherical fullerenes do not contain a core composed of impurity elements other than carbon.

[0124] The morphological features of 3DG may be quanli lied according to three categories of features: flakes, nodules, and graphitic particles. FIG. 2A illustrates a transmission electron microcopy (TEM) of a 2D area of the surface of a 3D graphene (3DG). The images of FIG. 2A illustrate the following morphological features. Part (a) depicts a 3DG that is primarily flakes (i.e., flaky) having planar-like features as seen in the magnified view in the inset image. Part (b) depicts a 3DG that is primarily nodules (i.e., nodular) having spherical-like features as seen in the magnified view in the inset image. Part (c) depicts a 3DG that is primarily crumpled graphene particles having collapsed spherical-like particles as seen in the magnified view in the inset image. Part (d) depicts a 3DG that has features termed “crusty donut” that has seemingly rigid edges of a collapsed spherical-like particle as seen in the magnified view in the inset image. In some approaches, a morphology of 3DG is a crumpled 3D structure having a lot of kinks and resembles “broccoli florets”. The floret-type morphology is not a spherical shape. 3DG having a flaky morphology has a higher aspect ratio than a 3DG having a nodular morphology.

[0125] In comparison, conventional 2D graphene has a platelet-like structure. FIG. 2B depicts SEM images of conventional platelet-like 2D graphene oxide compounds of graphene oxide (part (a)) and reduced graphene oxide (rGO). The morphology of GO and rGO is distinct from the various structural features of 3DG whose morphology may be characterized by flakes, nodules, crumpled spherical shaped particles, and florets. 3DG has a much higher order than commercial graphene oxide. Table 1 lists a comparison of metrology data of one example of 3DG to-34- LYT IP 134.P_LYTEP322WOcommercial graphene oxide. Most notable, Raman spectroscopy analysis demonstrates that the tested 3DG has a D / G intensity (ID / IG) of less than 0.50 (e.g., 0.48) whereas commercial graphene oxide and commercial reduced graphene oxide have ID / IG near 1.0 or greater, (e.g., 0.97 and 1.4, respectively). The higher order of 3DG may be attributed to a method of fabrication being “bottom up” synthesis from gases as opposed to the more conventional process of “top down” approach used to generate commercial graphene oxide. “Top down” is typically described as exfoliating or peeling layers away from bulk material that is harvested from natural sources (e.g., mined, heating SiC to remove Si, etc.).Table 1. Metrology data of one example of 3DG and Commercial GO and Commercial reduced GOCharacteristics 3DG Commercial Commercial GO reduced GO (rGO)SSA (m2 / g) 129.7 366.8 459.8% Oxygen - 16.8 0.25 ID / IG 0.48 0.97 1.4La (nm) 30.5 10.0 10.2

[0126] PRISTINE CARBONS FOR EPOXY RESIN

[0127] According to various aspects of this present invention, nodular morphologies of graphene-containing material affect physical properties of polymer matrices throughout which the graphene-containing material is dispersed. In one approach, graphene-containing material is a pristine carbon that may be defined as a carbon allotrope that is not a functionalized carbon allotrope. Pristine carbon may include essentially three-dimensional (3D ) graphene that is not functionalized, such as unfunctionalized 3DG. A functionalized graphene has functional groups associated with the graphene structure.

[0128] According to one aspect, pristine carbon is 3D graphene having nodular morphology. Nodular morphology may be defined as a self-nucleated graphilic-35- LYT IP 134.P_LYTEP322WOcarbonaceous material having a spherical-like structure. Multiple nodular 3DG forms may be clumped together, in a string of spheres (i.e., a string of pearls), intermixed with flaky morphology, etc.). Pristine carbon is 3D graphene also having flaky morphology. Flaky morphology may be defined as self-nucleated graphitic carbonaceous material having planar-like features. In one approach, pristine carbon includes 3D graphene having a mixed morphology characterized by nodular morphology and flaky morphology. FIG. 3 is a scanning electron microscope (SEM) image of a sample of an unfunctionalized 3DG that is representative of pristine carbon. The image in FIG. 3 depicts nodules and flakes in the unfunctionalized 3DG sample.

[0129] In some approaches, an unlunclionalized 3DG may have a D / G ratio of Raman band intensities of the unl unclionalized graphene in a range of 0.3 to 1.0, or 0.3 to 0.8, or 0.3 to 0.6, or 0.4 to 1.0, or 0.4 to 0.8. For example, in one approach as listed in the metrology data of unfunctionalized 3DG in Table 2, the D / G ratio of Raman band intensity is 0.48. . In some approaches, the unlunclionalized 3DG may have a surface area in a range of 50 to 300 meter squared per gram (m2 / g), or 50 to 200 m2 / g, or 50 to 100 m2 / g, or 100 to 200 m2 / g, or 100 to 300 m2 / g. In one example, as listed in Table 2, the surface area of unfunctionalized 3DG is 129.65 m2 / g.Table 2: Metrology data of unfunctionalized 3DG2D:G Intensity D:G Intensity La (nm) SSA: Surface Area (m2 / g)0.77 0.48 30.50 129.65

[0130] EPOXY ADEHSIVE SYSTEM

[0131] Mechanical fasteners such as bolts and screws require drilling through panels, which compromises structural integrity, adds weight, and creates sites for galvanic corrosion. Structural adhesives eliminate these drawbacks, but most commercial grades lose strength when exposed to the elevated temperatures commonly found near exhaust systems, engines, and brakes. Thermal degradation in the 80 °C - 100 °C range leads to adhesive softening, loss of lap-shear strength, and eventual delamination — failures that drive costly rework and jeopardize safety in-36- LYT IP 134.P_LYTEP322WOaerospace, automotive, and motorsports assemblies. According to one aspect, a structural adhesive is formulated to retain mechanical performance across that crilical temperature window, enabling lighter, corrosion-free joints that remain reliable under continuous thermal stress. By extending adhesive durability into higher service temperatures, the technology addresses a long-standing limitation of existing products and unlocks broader use of bonding solutions in high-heat zones.

[0132] Conventional adhesives experience thermal softening and delamination of bonded joints at well-known pain-points, especially around engines, exhausts, and brakes. Commercial suppliers and academic researchers have tackled it in three main approaches, and each of these approaches have demonstrated challenges. The approach of switching to bismaleimide (BMI) or methacrylate chemistries with glasstransition temperatures (Tg) well above the 80 - 100 °C service window results in high cure temperatures and longer cycles that tend to induce brittle, low-peal joints. Moreover, methacrylates bring strong exotherm shrinkage, odor, and volatile organic compounds (VOCs). (ii) The approach of formulating one -part, heat-curing epoxies that fully cross-link in the paint oven or autoclave to maximize network density results in risks of cold-chain lapses, crystallization, and filler sedimentation, (iii) The approach of using stoichiometry changes or nano-fillers (e.g., core-shell rubber, ZnO, CNTs) to push Tg upward while retaining toughness is problematic because nanofillers increase viscosity, complicate mixing and dispensing. Moreover, agglomeration harms toughness and quality control reproducibility.

[0133] In some applications such as aerospace and high performance automobile applications, a structural adhesive needs to demonstrate high performance of bond strength at room temperature and at elevated temperatures above room temperature. In one aspect, at environmental temperatures above 80 °C, preferably between 80 °C to greater than 100 °C , a structural adhesive maintains high performance of adhesion, bond strength, shear strength, etc. Moreover, the adhesive demonstrates high performance of adhesion on dissimilar surfaces such as metal, plastic, carbon fiber reinforced polymer (CFRP), etc. without risk of delamination of the adhesive from the surface, i.e., the adherend.

[0134] According to one aspect, an epoxy adhesive, EA 3DG, is comprised of 2 parts - Part A (epoxy resin) and Part B (amine hardener). EA 3DG epoxy adhesive-37- LYT IP 134.P_LYTEP322WOdifferentiates itself from commercial products in the market as follows. First, composite EA 3DG shows excellent thermal stability when tested at 90°C on Al-Al substrate, showing +23% and +111% improvement over commercially available structural adhesives Ad 1 and Ad 2, respectively. Second, the lap shear strength performance of composite EA 3DG on CFRP-CFRP at 90 °C (18.2 MPa) is comparable to commercially available structural adhesive Ad 2 at RT (18.7 MPa).Third, although composite EA 3DG shows some decreased bond strength at the highest temperature of 110 °C, the performance of EA 3DG at 110°C is comparable to the performance of commercially available Ad 1 at the lower temperature of 90°C.

[0135] According to one aspect, a formulation of an epoxy polymer system is a two-part adhesive formulation having a Part A and Part B. Part A includes the epoxy resin having the following components: a di-functional epoxy resin, a tetra-functional epoxy resin, a thermoplastic toughener, an adhesion promoter, fumed silica, and milled glass fiber. Table 3A lists the components, the role of each component in the formulation of Part A, and the loading ranges in weight% (wt%) of total weight of Part A. The formulation includes 90 wt% epoxy resin being a combination of difunctional epoxy resin and tetra-functional epoxy resin. The remaining 10 wt% of the formulation is comprised of a thermoplastic hardener, an adhesion promoter, a rheology modifier, and a reinforcing filler.Table 3A: Components of Part A of 2-Part Epoxy Adhesive Formulation Component Role Loading Ranges (wt%) Di-functional epoxy resin Primary backbone resin 45 - 70 Tetra-functional epoxy resin Tightens crosslinked network and20-45 increases TgThermoplastic toughener Enhances peel strength 1 - 10-38- LYT IP 134.P_LYTEP322WOAdhesion promoter Enhances adhesion to metal and1 - 3 inorganic surfacesFumed silica Rheology modifier / thixotropic2 - 8 agentMilled glass fiber Induces micro-reinforcement 2 - 8

[0136] According to select approaches, the di-functional epoxy resin and the tetrafunctional epoxy resin may be present in a particular weight ratio with respect to one another to equal 90 wt% of Part A. Of course, it shall be understood that in the context of the presently described inventive concepts, the relative amounts of difunctional epoxy resin and tetra-functional epoxy resin may be of any value within the broad range set forth above. Different amounts of di-functional epoxy resin and tetra-functional epoxy resin may be selected based on the particular application and / or composition of other components of Part A, based on the composition of other components Part A and / or based on the composition and / or amount of other components of Part B that comprise the epoxy adhesive system described herein as will be understood by those having ordinary skill in the art upon reading the present disclosure.

[0137] Tables 3B and 3C below summarize various suitable compositions of the epoxy resins and additional components of the inventive Part A of an epoxy adhesive system described hereinabove, respectively, and according to several exemplary aspects. It shall be understood that the exemplary aspects set forth in the tables are provided by way of illustration rather than limitation, and other compositions falling within the scope of the disclosure provided herein may be employed without departing from the scope of the inventive concepts presented herein.

[0138] Moreover, for brevity and organizational simplicity, the tables describe different components and suitable amounts individually, and in select combinations, but it shall be understood that any combination of different species may be employed in suitable amounts as informed by the broad ranges presented above may be employed without departing from the scope of the presently described inventive concepts.-39- LYT IP 134.P_LYTEP322WO

[0139] For instance, any number of different species of di-functional epoxy resin, tetra-functional epoxy resin, thermoplastic hardener, adhesion promoter, rheology modifier, and reinforcement filler may be included in an epoxy adhesive system composition with the only limitation being that the total amount of di-functional epoxy resin, tetra-functional epoxy resin, thermoplastic hardener, adhesion promoter, rheology modifier, and reinforcement filler, respectively, fall within the broad ranges set forth hereinabove for the respective component.Table 3B. Exemplary epoxy resin components of Part A, 90 wt% of Part ADi-functional epoxy resin Tetra-functional epoxy resinwt% wt%45.0 45.045.5 44.546.0 44.046.5 43.547.0 43.047.5 42.548.0 42.048.5 41.549.0 41.049.5 40.550.0 40.050.5 39.551.0 39.051.5 38.552.0 38.052.5 37.553.0 37.0-40- LYT IP 134.P_LYTEP322WO36.536.035.535.034.534.033.533.032.532.031.531.030.530.029.529.028.528.027.527.026.526.025.525.024.5-41- LYT IP 134.P_LYTEP322WO66.0 24.066.5 23.567.0 23.067.5 22.568.0 22.068.5 21.569.0 21.069.5 20.570.0 20.0Table 3C. Exemplary components of Part A, 10 wt% of Part AThermoplastic Adhesion Rheology Reinforcement hardener promoter modifier filler wt% wt% wt% wt%10.0 0.0 0.0 0.08.5 1.0 0.5 0.08.5 1.5 0.0 0.07.0 1.0 1.0 1.07.0 1.5 1.5 0.07.0 1.5 0.0 1.57.0 2.0 1.0 0.07.0 2.0 0.0 1.07.0 3.0 0.0 0.0-42- LYT IP 134.P_LYTEP322WO1.5 1.01.0 1.51.0 1.01.5 0.00.0 1.51.0 0.00.0 1.02.0 2.02.0 3.03.0 2.00.0 3.51.0 2.51.5 2.02.0 1.52.5 1.00.0 3.01.0 2.01.5 1.52.0 1.0-43- LYT IP 134.P_LYTEP322WO3.0 0.00.0 2.51.0 1.51.5 1.02.5 0.00.0 2.01.0 1.02.0 0.00.0 5.51.0 4.51.5 4.02.0 3.52.5 3.03.0 2.53.5 2.04.0 1.54.5 1.01.0 4.01.5 3.5-44- LYT IP 134.P_LYTEP322WO2.0 3.02.5 2.53.0 2.03.5 1.54.0 1.01.0 3.51.5 3.02.0 2.52.5 2.03.0 1.53.5 1.01.0 3.01.5 2.52.0 2.02.5 1.53.0 1.01.0 2.51.5 2.02.0 1.5-45- LYT IP 134.P_LYTEP322WO2.5 1.01.0 6.01.5 5.52.0 5.02.5 4.53.0 4.03.5 3.54.0 3.04.5 2.55.0 2.05.5 1.56.0 1.01.5 5.02.0 4.52.5 4.03.0 3.53.5 3.04.0 2.54.5 2.0-46- LYT IP 134.P_LYTEP322WO5.0 1.55.5 1.01.5 4.52.0 4.02.5 3.53.0 3.03.5 2.54.0 2.04.5 1.55.0 1.01.5 4.02.0 3.52.5 3.03.0 2.53.5 2.04.0 1.54.5 1.01.5 3.52.0 3.0-47- LYT IP 134.P_LYTEP322WO2.5 2.53.0 2.03.5 1.54.0 1.00.0 8.01.0 7.01.5 6.52.0 6.02.5 5.53.0 5.03.5 4.54.0 4.04.5 3.55.0 3.05.5 2.56.0 2.06.5 1.57.0 1.08.0 0.0-48- LYT IP 134.P_LYTEP322WO1.5 6.02.0 5.52.5 5.03.0 4.53.5 4.04.0 3.54.5 3.05.0 2.55.5 2.06.0 1.56.5 1.01.5 5.52.0 5.02.5 4.53.0 4.03.5 3.54.0 3.04.5 2.55.0 2.0-49- LYT IP 134.P_LYTEP322WO1.0 2.5 1.5 5.01.0 2.5 2.0 4.51.0 2.5 2.5 4.01.0 2.5 3.0 3.51.0 2.5 3.5 3.01.0 2.5 4.0 2.51.0 2.5 4.5 2.01.0 2.5 5.0 1.51.0 2.5 5.5 1.01.0 3.0 1.5 4.51.0 3.0 2.0 4.01.0 3.0 2.5 3.51.0 3.0 3.0 3.01.0 3.0 3.5 2.51.0 3.0 4.0 2.01.0 3.0 4.5 1.51.0 3.0 5.0 1.0

[0140] The di-functional epoxy resin is present to provide the primary backbone resin of the formulation. A di-functional epoxy resin includes two epoxy groups. For example, a di-functional epoxy resin includes polymers that may have two glycidyl-50- LYT IP 134.P_LYTEP322WOgroups, a glycidyl group being a reactive three-membered epoxy ring containing a -CH2OCH functional group. Examples of di-functional epoxy resins present in Part A include bisphenol-A diglycidyl ether (DGEBA)(2,2-bis(4-hydroxyphenyl)-propane diglycidyl ether), Bisphenol-F diglycidyl ether (DGEBF)( 2, 2'-(4, d'-dihydroxy diphenyl)methane diglycidyl ether), cycloaliphatic diepoxy (3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane-l-carboxylate), resorcinol diglycidyl either (RDGE) ( l,3-bis(2,3-epoxypropoxy)benzene), neopentyl-glycol diglycidyl ether (NPGDGE)( 2,2-dimethyl-l,3-propanediol diglycidyl ether), tetrabromobisphenol-A diglycidyl ether (TBBPA-DGE)( 3,3',5,5'-tetrabromo-2,2-bis(4-hydroxyphenyl)-propane diglycidyl ether), etc.

[0141] According to one approach, the formulation of Part A includes a mulli-functional epoxy resin that is a polymer having greater than three (3) epoxy groups. In one approach, a multi-functional epoxy resin may be included to tighten the crosslinked polymer network and increase the glass transition temperature (Tg) of the adhesive resin. In a preferred approach, a tetra- functional resin being an epoxy that has four reactive epoxy groups per molecule is present in the formulation of Part A. The presence of a multi-functional epoxy resin may lead to a tighter more rigid polymer network after curing which in turn enhances thermal and mechanical properties. Preferably, an amount of tetra-functional epoxy resin is greater than 20 wt% of the total amount of Part A. Less than 20 wt% of tetra-functional epoxy resin may not affect the Tg of the adhesive resin. Examples of tetra-functional epoxy resins include tetra-functional glycidyl-amine (N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl-methane (TGDDM), 4,4’ -methylenebis(N,N-diglycidylaniline) (MBDGA)), low viscosity tetra-functional glycidyl-amine (N,N,N',N'-tetraglycidyl-4,4'-methylenedianiline (TGMDA)), phenolic novolac (average 4 - 6) (Phenolic novolac polyglycidyl ether), cresol novolac (average 4 - 7) (o-Cresol novolac polyglycidyl ether), cyclotriphosphazene (6) (Hexaglycidyl cyclotriphosphazene), bio-based polyol-derived (4 - 8) (Sucrose polyglycidyl ether (up to octa-epoxy per molecule)), etc.

[0142] According to one approach, a thermoplastic toughener is present in the formulation of Part A to increase the peel strength in the cured adhesive. Examples of a thermoplastic toughener include polyethersulfone (PES) (Poly(phenylene sulfone),-51- LYT IP 134.P_LYTEP322WOpolyetherimide (PEI), polyphenylene ether (PPE) (Poly(2,6-dimethyl-l,4-phenylene oxide), phenoxy resin (Poly(hydroxyether of bisphenol A), Polyaryletherketone (PEKK) (Poly(ether ketone ketone), Polyamide 12 powder (Poly(laurolactam), etc.

[0143] According to one approach, an adhesion promoter is present in the formulation of part A to enhance adhesion properties of the adhesive between metal and inorganic surfaces. In some approaches, an adhesion promoter functions as a coupling agent for bonding between organic resins and inorganic surfaces (e.g., glass, metal, etc.) Examples of an adhesion promoter include epoxy-functional silane (3-Glycidoxypropyltrimethoxysilane, y-Glycidoxypropylmethyldiethoxysilane, 3-glycidyloxypropyl)trimethoxysilane (GP-TMS)), amino-functional silane (3-Aminopropyltriethoxy silane), diamino-functional silane (N-P-(Aminoethyl)-y-aminopropyltrimethoxy silane), Mercapto-functional silane (3-Mercaptopropyltrimethoxysilane), Titanate coupling agent (Neoalkoxy tri(dioctyl)phosphato lilanale). Organophosphate promoter (10-Phosphonobenzoic acid), etc.

[0144] According to one approach, fumed silica is present in the formulation of Part A as a rheology modifier or thixotropic agent of the uncured adhesive. Examples of fumed silica include hydrophilic fumed silica having a BET of about 200 m2 / g, 300 m2 / g, 130 m2 / g; HMDS-treated hydrophobic fumed silica, DDS-treated hydrophobic fumed silica, siloxane-treated hydrophobic fumed silica (hydrophobic SiO2-PDMS), etc. Milled glass fiber may be present in the formulation as a reinforcing filler that induces micro- reinforcement.

[0145] According to one aspect, Part B of the 2-part epoxy adhesive system is an amine hardener. Table 4A lists components present in Part B and their role and loading ranges in wt% relali vc to a total weight of Part B (100 wt%). Part B includes unfunctionalized 3DG present in an amount ranging from greater than 0.01 wt% up to 1 wt%. Table 4B summarizes various suitable compositions of exemplary components (piperazine, liquid rubber, reactive diluent, rheology modifier, and 3DG) for 90 wt% of the total weight of the formulation of Part B of an epoxy adhesive system described hereinabove, respectively, and according to several exemplary aspects. Accordingly, in some approaches, the remaining 10 wt% of the Part B formulation may include a combination of the auxiliary amines and primary, secondary, and tertiary amines total.-52- LYT IP 134.P_LYTEP322WOIt shall be understood that the exemplary aspects set forth in the tables are provided by way of illustration rather than limitation, and other compositions falling within the scope of the disclosure provided herein may be employed without departing from the scope of the inventive concepts presented herein.Table 4A: Components of Part B of 2-Part Epoxy Adhesive Formulation Component Role Loading Ranges (wt%) Piperazine with primary Main component for crosslinking45 - 60 amine functional groups with epoxy resinAmine-terminated Liquid rubber for enhanced peel25 - 35 poly)butadiene-acrylonitrile strength / rheology modifierDifunctional primary amine Auxiliary amine 1 - 10 Aromatic ring with hydroxyl Reactive diluent, promotes curing0.5 - 5 groupDifunctional primary amine Auxiliary amine, also helps in part1 - 5 on flexible backbone with compalibi lizationPrimary, secondary, and Amine that promotes curing0.5 - 5 tertiary amineFumed silica Rheology modifier / thixotropic1 - 15 agent3D graphene Adds strength and enhances< 1 thermal stability-53- LYT IP 134.P_LYTEP322WOTable 4B. Exemplary components of a formulation of Part B, 90 wt% of Part B RheologyPiperazine Liquid rubber Diluent 3D Graphene modifierWt% Wt% Wt% Wt% Wt%60.0 25.0 4.9 0.0 0.160.0 25.0 4.7 0.0 0.360.0 25.0 4.5 0.0 0.560.0 25.0 4.3 0.0 0.760.0 25.0 4.1 0.0 0.960.0 25.0 3.0 1.9 0.160.0 25.0 3.0 1.7 0.360.0 25.0 3.0 1.5 0.560.0 25.0 3.0 1.3 0.760.0 25.0 3.0 1.1 0.960.0 25.0 1.5 3.4 0.160.0 25.0 1.5 3.2 0.360.0 25.0 1.5 3.0 0.560.0 25.0 1.5 2.8 0.760.0 25.0 1.5 2.6 0.955.8 25.0 5.0 4.1 0.1-54- LYT IP 134.P_LYTEP322WO5.0 3.9 0.35.0 3.7 0.55.0 3.5 0.75.0 3.3 0.94.3 4.8 0.14.3 4.6 0.34.3 4.4 0.54.3 4.2 0.74.3 4.0 0.93.0 6.1 0.13.0 5.9 0.33.0 5.7 0.53.0 5.5 0.73.0 5.3 0.91.5 7.6 0.11.5 7.4 0.31.5 7.2 0.51.5 7.0 0.71.5 6.8 0.9-55- LYT IP 134.P_LYTEP322WO5.0 0.6 0.15.0 0.4 0.35.0 0.2 0.55.0 0.0 0.74.3 1.3 0.14.3 1.1 0.34.3 0.9 0.54.3 0.7 0.74.3 0.5 0.93.0 2.6 0.13.0 2.4 0.33.0 2.2 0.53.0 2.0 0.73.0 1.8 0.91.5 4.1 0.11.5 3.9 0.31.5 3.7 0.51.5 3.5 0.71.5 3.3 0.9-56- LYT IP 134.P_LYTEP322WO5.0 9.5 0.15.0 9.3 0.35.0 9.1 0.55.0 8.9 0.75.0 8.7 0.94.3 10.2 0.14.3 10.0 0.34.3 9.8 0.54.3 9.6 0.74.3 9.4 0.93.0 11.5 0.13.0 11.3 0.33.0 11.1 0.53.0 10.9 0.73.0 10.7 0.91.5 13.0 0.11.5 12.8 0.31.5 12.6 0.51.5 12.4 0.7-57- LYT IP 134.P_LYTEP322WO1.5 12.2 0.95.0 6.0 0.15.0 5.8 0.35.0 5.6 0.55.0 5.4 0.75.0 5.2 0.94.3 6.7 0.14.3 6.5 0.34.3 6.3 0.54.3 6.1 0.74.3 5.9 0.93.0 8.0 0.13.0 7.8 0.33.0 7.6 0.53.0 7.4 0.73.0 7.2 0.91.5 9.5 0.11.5 9.3 0.31.5 9.1 0.5-58- LYT IP 134.P_LYTEP322WO1.5 8.9 0.71.5 8.7 0.95.0 2.4 0.15.0 2.2 0.35.0 2.0 0.55.0 1.8 0.75.0 1.6 0.94.3 3.1 0.14.3 2.9 0.34.3 2.7 0.54.3 2.5 0.74.3 2.3 0.93.0 4.4 0.13.0 4.2 0.33.0 4.0 0.53.0 3.8 0.73.0 3.6 0.91.5 5.9 0.11.5 5.7 0.3-59- LYT IP 134.P_LYTEP322WO1.5 5.5 0.51.5 5.3 0.71.5 5.1 0.94.3 0.2 0.14.3 0.0 0.33.0 1.5 0.13.0 1.3 0.33.0 1.1 0.53.0 0.9 0.73.0 0.7 0.91.5 3.0 0.11.5 2.8 0.31.5 2.6 0.51.5 2.4 0.71.5 2.2 0.95.0 11.3 0.15.0 11.1 0.35.0 10.9 0.55.0 10.7 0.7-60- LYT IP 134.P_LYTEP322WO5.0 10.5 0.94.3 12.0 0.14.3 11.8 0.34.3 11.6 0.54.3 11.4 0.74.3 11.2 0.93.0 13.3 0.13.0 13.1 0.33.0 12.9 0.53.0 12.7 0.73.0 12.5 0.91.5 14.8 0.11.5 14.6 0.31.5 14.4 0.51.5 14.2 0.71.5 14.0 0.95.0 7.8 0.15.0 7.6 0.35.0 7.4 0.5-61- LYT IP 134.P_LYTEP322WO5.0 7.2 0.75.0 7.0 0.94.3 8.5 0.14.3 8.3 0.34.3 8.1 0.54.3 7.9 0.74.3 7.7 0.93.0 9.8 0.13.0 9.6 0.33.0 9.4 0.53.0 9.2 0.73.0 9.0 0.91.5 11.3 0.11.5 11.1 0.31.5 10.9 0.51.5 10.7 0.71.5 10.5 0.95.0 4.2 0.15.0 4.0 0.3-62- LYT IP 134.P_LYTEP322WO5.0 3.8 0.55.0 3.6 0.75.0 3.4 0.94.3 4.9 0.14.3 4.7 0.34.3 4.5 0.54.3 4.3 0.74.3 4.1 0.93.0 6.2 0.13.0 6.0 0.33.0 5.8 0.53.0 5.6 0.73.0 5.4 0.91.5 7.7 0.11.5 7.5 0.31.5 7.3 0.51.5 7.1 0.71.5 6.9 0.95.0 1.3 0.1-63- LYT IP 134.P_LYTEP322WO5.0 1.1 0.35.0 0.9 0.55.0 0.7 0.75.0 0.5 0.94.3 2.0 0.14.3 1.8 0.34.3 1.6 0.54.3 1.4 0.74.3 1.2 0.93.0 3.3 0.13.0 3.1 0.33.0 2.9 0.53.0 2.7 0.73.0 2.5 0.91.5 4.8 0.11.5 4.6 0.31.5 4.4 0.51.5 4.2 0.71.5 4.0 0.9-64- LYT IP 134.P_LYTEP322WO5.0 14.9 0.15.0 14.7 0.35.0 14.5 0.55.0 14.3 0.75.0 14.1 0.94.3 15.0 0.74.3 14.8 0.95.0 11.4 0.15.0 11.2 0.35.0 11.0 0.55.0 10.8 0.75.0 10.6 0.94.3 12.1 0.14.3 11.9 0.34.3 11.7 0.54.3 11.5 0.74.3 11.3 0.93.0 13.4 0.13.0 13.2 0.3-65- LYT IP 134.P_LYTEP322WO3.0 13.0 0.53.0 12.8 0.73.0 12.6 0.91.5 14.9 0.11.5 14.7 0.31.5 14.5 0.51.5 14.3 0.71.5 14.1 0.95.0 7.8 0.15.0 7.6 0.35.0 7.4 0.55.0 7.2 0.75.0 7.0 0.94.3 8.5 0.14.3 8.3 0.34.3 8.1 0.54.3 7.9 0.74.3 7.7 0.93.0 9.8 0.1-66- LYT IP 134.P_LYTEP322WO3.0 9.6 0.33.0 9.4 0.53.0 9.2 0.73.0 9.0 0.91.5 11.3 0.11.5 11.1 0.31.5 10.9 0.51.5 10.7 0.71.5 10.5 0.95.0 4.9 0.15.0 4.7 0.35.0 4.5 0.55.0 4.3 0.75.0 4.1 0.94.3 5.6 0.14.3 5.4 0.34.3 5.2 0.54.3 5.0 0.74.3 4.8 0.9-67- LYT IP 134.P_LYTEP322WO45.0 35.0 3.0 6.1 0.145.0 35.0 3.0 6.7 0.345.0 35.0 3.0 6.5 0.545.0 35.0 3.0 6.3 0.745.0 35.0 3.0 6.1 0.945.0 35.0 1.5 8.4 0.145.0 35.0 1.5 8.2 0.345.0 35.0 1.5 8.0 0.545.0 35.0 1.5 7.8 0.745.0 35.0 1.5 7.6 0.9

[0146] In one approach, piperazine is the main component for crosslinking with the epoxy resin in Part A. Preferably, piperazine has primary amine functional groups. Examples of piperazine present in the formulation of Part B include base piperazine, mono-substituted piperazine (l-(2-Aminoethyl)piperazine (AEP)), Di-(3- aminopropyl) piperazine (N,N'-Bis(3-aminopropyl)piperazine (BAPP)), Di-(2- aminoethyl) piperazine (N,N'-Bis(2-aminoethyl)piperazine (BAEP)), Hydroxysubstituted piperazine (l-(2-Hydroxyethyl)piperazine (HPP)), Methyl-substituted piperazine (2-Methylpiperazine (2-MP)), etc.

[0147] In various approaches, the liquid rubber component is included to balance strength with flexibility. In some approaches, liquid rubber may be replaced with other forms of liquid rubber that are well-known in the art.

[0148] According to one approach, a reactive diluent includes a solvent having an aromatic ring with hydroxyl group is present in the formulation of Part B to promote curing. Examples of the solvent include aromatic alcohol diluent (4-nonylphenol,-68- LYT IP 134.P_LYTEP322WObenzyl alcohol, 4-tert-butylphenol, 2 -phenoxyethanol, phenyl glycidyl ether, etc.), cycloaliphatic alcohol diluent (cyclohexanemethanol), aromatic ether-alcohol diluent (2-(benzyloxy)ethanol), etc.

[0149] According to one approach, a treated fumed silica is present in the formulation of Part B as a thixotropic agent / rheology modifier. Examples of the treated fumed silica include standard hydrophilic fumed silica (BET ~ 200 m2 / g), high-surface-area hydrophilic fumed silica (BET ~ 380 m2 / g), medium-surface-area hydrophilic fumed silica (BET ~ 300 m2 / g), low- surface-area hydrophilic fumed silica (BET ~ 130 m2 / g), mixed-oxide hydrophilic fumed silica / alumina, low-densified hydrophilic fumed silica, high-purity hydrophilic fumed silica, etc.

[0150] The auxiliary amines serve more than two functions each. The auxiliary amines of the Part B formulation are integrated as part of the epoxy-amine crosslinked network. In addition, the auxiliary amines may also be included to enhance flexibility, increase compatibility, expediate the curing process, etc. In some approaches, the auxiliary amines may not be essential to the formulation of Part B. According to one approach, a difunctional primary amine (e.g., isophorone diamine) is present in the formulation of Part B as an auxiliary amine. Examples of the di functional amine include cycloaliphatic diamine (3-aminomethyl-3,5,5-trimethylcyclohexylamine (IPDA), 4,4'-Methylenebis(cyclohexylamine) (PACM), 1,3- Bis(aminomethyl)cyclohexane (BAG), 1,2-Diaminocyclohexane, etc.), Aromaticcycloaliphatic diamine (m-Xylylenediamine), Branched aliphatic diamine (2,2,4 / 2,4,4-Trimethylhexamethylenediamine), Linear aliphatic diamine (2-Methyl-1,5 -pentanediamine), etc.

[0151] According to one approach, a difunctional primary amine on flexible backbone is present in the formulation of Part B as another auxiliary amine that also helps in part with compalibilizalion. Examples of the difunctional primary amine on flexible backbone include 3,3'-Oxybis(ethyleneoxy)bis(propylamine)(APDEG), low-MW polyethylene glycol) (PEG) diamine (4,7,10-Trioxa-l,13-tridecanediamine (APDEG)), PEG diamine, Mn ~ 150 (a,co-Bis(aminopropyl)-poly(ethylene glycol), PEG diamine, Mn ~ 600 (Poly(ethylene glycol) bi s(3 -aminopropyl) ether (Jeffamine ED-600)), PEG diamine, Mn ~ 900 (Polyethylene glycol) bis(3-aminopropyl) ether (Jeffamine ED-900)), PEG diamine, Mn ~ 2000 (Poly(ethylene glycol) bis(3--69- LYT IP 134.P_LYTEP322WOaminopropyl) ether (Jeffamine ED-2003)), PEG diamine, Mn ~ 4000 (Poly(ethylene glycol) bis(3-aminopropyl) ether (Jeffamine ED-4000)), Ethylene-oxide-rich polyether diamine (Amino-terminated poly(oxyethylene-oxypropylene) (Jeffamine EDR- 148)), etc.

[0152] According to one approach, a primary, secondary, or tertiary amine is present in the formulation of Part B to promote curing. Examples of a primary, secondary, or tertiary amine include 2-piperazin-l-ylethylamine, N-aminoethylpiperazine (NAEP), etc.

[0153] In various approaches, curing conditions of the epoxy adhesive system, Parts A and B, may vary depending on the adherend in the application. In one approach, the epoxy adhesive system may include curing at 65 °C for about one hour, a curing condition that may be preferred for a metal adherend, such as aluminum. In another approach, the epoxy adhesive system may include curing at 80 °C for about one hour, a curing condition that may be preferred for a polymer adherend such as carbon fiber reinforced polymer (CFRP). In one example, curing the adhesive system on CFRP substrate at 80 °C demonstrated a 53.5% increase in lap shear strength in testing at room temperature (20 °C) compared to curing the adhesive system on CFRP substrate at 65 °C (23.8 MPa vs 15.5 MPa); and a 12.3% increase in lap shear strength in testing at 90 °C (18.2 MPa vs 16.2 MPa).

[0154] PHYSICAL PROPERTIES OF AN EPOXY ADHESIVE INCLUDING PRISTINE CARBON

[0155] In one aspect, a composite material includes a polymer and a graphenecontaining material having nodular and / or flaky morphologies. In one approach, the graphene-containing material is unfunctionalized 3DG and may be referred to as pristine carbon. In one approach, the graphene-containing material is essentially carbon. Pristine carbon (i.e., unfunctionalized 3DG) is dispersed and suspended in the polymer network and does not react, bond, etc. with the polymer chain of the polymer network.

[0156] In sharp contrast, functionalized 3DG may react with epoxy and become a part of the polymer network. Unfunctionalized 3DG does not react with the polymer network. Unfunctionalized 3DG is dispersed evenly throughout the polymer matrix of-70- LYT IP 134.P_LYTEP322WOthe composite where the distribution of nodular and flaky morphologies is even across and throughout the polymer matrix. The uniform distribution of both morphologies, nodular and flaky, allows for an even di st ri but i o n of force to the polymer matrix, thereby enhancing tensile lap shear strength, in some approaches. Additionally, dispersed graphene particulates having different morphologies stop the crack propagation when force is applied, promoting a cohesive failure mode.

[0157] As described more fully elsewhere, graphene-containing material (e.g., pristine carbon, unfunctionalized 3DG, etc.) is a reactor carbon derived solely from methane. Pristine carbon is essentially free of oxygen-containing species. In one approach, graphene-containing material as described herein includes less than 1% of an oxygen-containing species. The graphene-containing material has a crystalline structure and has a D / G ratio of Raman band intensities between 0.3 and 1.

[0158] FIG. 4 illustrates a scheinalic diagram of physical effects (e.g., force, shock, etc.) on a polymer matrix that includes carbon having mixed morphology (i.e., nodular and flaky 3DG) and how the presence of mixed morphology carbon alters the physical effects. Pristine carbon may also be referred to as 3D graphene (3DG) having a mixed morphology (e.g., nodular, flaky, etc.). Part (a) illustrates the effect 400 of force shock 402 on a polymer matrix 404 having nodular 3DG 406 and flaky 3DG 408 interspersed within an epoxy polymer chain 410. The polymer matrix may also be referred to as a composite material. Nodular 3DG morphologies have a morphology that is round, lump-like, spherical-like, quasi-spherical, etc. Multiple nodules form quasi-spherical aggregates (e.g., like a string of pearls) that may function like microspring aggregates in which multiple layers of graphene bend and fold, creating a localized “cushion-like” effect within the crosslinked polymer matrix.

[0159] In one approach, aggregates of nodular 3D graphene may form an active site that functions as an energy well 412 in the polymer matrix that absorbs energy upon impaction and dissipates impact energy. When subjected to mechanical stress, these nodular aggregates can undergo slight elastic deformation, thereby cl'lccli vely oscillate the shock, thereby absorbing and dissipating impact energy. The presence of nodular 3DG preserves the integrity of the polymer matrix by functioning as microscale buffers that inhibit crack inilialion and crack propagation, due to their curved interfaces and interconnected layers, which can store and subsequently release strain-71- LYT IP 134.P_LYTEP322WOenergy. The aggregates of nodular 3DG may cause the polymer matrix to respond with elastic bending under load, e.g., helping to cushion sudden stresses. As a result, the presence of nodular 3DG enhances fracture toughness, impact resistance, and overall durability in the polymer composite system.

[0160] Without being bound by any one theory, 3D graphene having nodular and flaky morphologies may have more than an A + B effect on the polymer matrix, where A is the effect of having a nodular 3DG and B is the effect of having a flaky 3DG. The presence of nodular and flaky morphologies of 3DG may have a synergistic effect on the response of a polymer to applied force and / or stress. Moreover, the nodular and flaky morphologies may provide a complementary reinforcement effect. In various approaches, the physical properties of the polymer may be tuned by the presence of 3DG having a predefined content of different morphologies (e.g., more nodular and less flaky, less nodular and more flakey, predominately flaky, predominately nodular, etc.) In some approaches, the composite material of polymer and carbon having mixed morphology may demonstrate mechanical strength and toughness. In other applications, a composite material may not have both toughness and strength, because in some instances when stiffness is improved then the toughness decrease, and vice versa.

[0161] In one approach, flaky 3D graphene (3DG) morphologies are characterized as having thin, plate-like graphene sheets that have a large surface area and stronger inplane mechanical properties. According to various aspect of this present invention, flaky morphologies of graphene-containing material may affect physical properties of polymer matrices throughout which the graphene-containing material is dispersed. In one approach, graphene-containing material may be 3D graphene having flaky morphology. As illustrated in part (b) of FIG. 4, flaky morphologies of 3DG, e.g., flaky 3DG 408, may provide extensive interfacial bonding with the polymer chain 410 of the polymer matrix 404 having nodular 406 and flaky 408 morphologies. The interfacial bonding may include hydrogen bonding, hydrophobic-hydrophobic interaction, hydrophilic-hydrophilic interaction, etc. The morphological features of 3DG may not be covalently bonded or chemically bonded to the polymer chain of the polymer matrix. Under shear or tensile stress, these flaky structures with a high aspect ratio are active sites that function as barriers to crack growth. The larger surface area of flakes also-72- LYT IP 134.P_LYTEP322WOfacilitates efficient load transfer, reinforcing the polymer matrix and improving stiffness. Furthermore, when flaky 3DG 408 group together in layers, the layers of flaky 3DG 408 are interlocked within the crosslinked epoxy and appear as overlapping sheets 414 that may “slide” relative to one another under stress, contributing to an energydissipating mechanism. The large surface area of the layered, plate-like overlapping sheets 414 may provide extensive interfacial bonding with the epoxy polymer chains 410. Moreover, the overlapping sheets 414 of the layered flaky 3DG 408 may force crack paths to deviate thereby expending more energy before fracture. The high inplane strength of load transfer and reinforcement improves stiffness and tensile performance. The overlapping sheets 414 of flaky 3DG 408 may shift relative to each other thereby further mitigating stress.

[0162] Together, these nodular and flaky morphologies offer a complementary reinforcement effect, improving both the toughness and rigidity of the composite. Moreover, in some approaches, the mixed morphologies of 3DG present in a polymer composite may work in concert with each other for enhancing a physical property determined in one mechanical test without sacrificing another physical property determined by another mechanical test. Details of the methodology of 3D graphene and / or methods of forming 3D graphene can be found in U.S. Patent Application No.63 / 776,852 filed March 24, 2025, titled “ENGINEERED THREE-DIMENSIONAL (3D) GRAPHENE HYBRID MATERIALS FOR HIGH PERFORMANCE POLYOLEFIN COMPOSITES,” which is hereby incorporated by reference in its entirety.

[0163] According to various approaches, unfunctionalized 3DG (e.g., pristine carbon) in epoxy polymer matrix enhances 1) tensile lap shear strength, 2) failure mode in peel tests, and 3) glass transition temperature, which translates to 1) rigidity / strength, 2) better adhesion, and 3) thermal stability, respectively. In a preferred approach, unfunctionalized 3DG has nodular and flaky morphologies. In a preferred approach, unfunctionalized 3DG acts as a physical restrictor, reducing chain mobility and segmental motion, thereby increasing the glass transition temperature, and ensuring performance when exposed to elevated temperatures.

[0164] One aspect pertains to the incorporation of unfunctionalized 3DG into an epoxy system. Unfunctionalized 3DG functions as a physical restrictor, reducing chain-73- LYT IP 134.P_LYTEP322WOmobility and segmental motion. In one aspect, pristine carbon (i.e., unfunctionalized 3DG having mixed morphology) has an effect on the polymer matrix by raising the glass transition temperature (Tg) of the graphene-epoxy resin (composite, polymer matrix, etc.). The elevated Tg of the pristine carbon-epoxy composite (having a mixed morphology graphene) ensures superior thermal stability under high-temperature conditions.

[0165] In addition, unfunctionalized 3DG mixed morphologies interrupt crack propagation, promoting cohesive failure in peel tests and enhancing overall mechanical performance, including tensile lap shear strength. The peel test demonstrate the ductility and flexibility of the adhesive composite material. These advancements are particularly valuable in automotive and aerospace applications, where durability and reliability at elevated temperatures are critical.

[0166] Differential Scanning Calorimetry (DSC) temperature flow measures the glass transition temperature (Tg) of composite material of a polymer and a graphenecontaining material. In preferred approaches, the composite material that includes a polymer and graphene-containing material has a glass transition temperature (Tg) that is higher than the Tg of the polymer in absence of the graphene-containing material. In one approach, the Tg of the composite material that includes an epoxy resin and 3DG is at least 3 degrees Celsius (°C) higher than the Tg of an epoxy resin without 3DG. In some approaches, the Tg of the composite material that includes an epoxy resin and 3DG is at least 2°, 4°, 5°, etc. higher than the Tg of an epoxy resin without 3DG. In a preferred approach, the composite material includes unfunctionalized 3D graphene having nodular and / or flaky morphologies.

[0167] A first heating curve in DSC testing allows entropy measurements that reflect the energy that is released when the polymer network is being formed (i.e., curing of the polymer). In one approach, the composite material having the polymer and graphene-containing material has an exotherm enthalpy at least 10% lower than the exotherm enthalpy of the polymer in absence of the graphene-containing material. In a preferred approach, the exothermic reaction of an epoxy composite material (Part A and Part B) is lower in the presence of 3DG compared to an exothermic reaction that is typical for epoxy resins in absence of 3DG. Without wishing to be bound by-74- LYT IP 134.P_LYTEP322WOany theory, it is possible the nodular and flaky morphology of the 3DG absorbs the heat during the curing reaction and thus lowering the entropy of the reaction.

[0168] As illustrated in FIGS. 5A-5B and listed in Table 5, heat flow measurements in DSC were run with neat epoxy adhesive (EA) and a composite material that included epoxy adhesive and unfunctionalized 3DG (EA 3DG). FIG. 5A illustrates overlaid DSC that determines onset curing temperature, exotherm enthalpy, and peak temperature. The heat flow curve of neat epoxy adhesive (EA) illustrates a peak temperature of 95.20 °C , an enthalpy (normalized) of 388.42 J / g having an onset temperature of 54.67 °C. In contrast, the heat flow curve of the composite epoxy adhesive with unfunctionalized 3DG (EA 3DG) illustrates a lower exotherm enthalpy 328.89 J / g, a higher onset temperature of 61.93 °C, and a higher peak temperature 104.15 °C. Without wishing to be bound by any theory, it is believed that the added unfunctionalized graphene may be hindering epoxy chain mobility and proximity of reactive groups thereby causing lower exotherm enthalpy, higher onset temperature and a higher peak temperature.

[0169] FIG. 5B illustrates calculation of glass transition temperature Tg of neat epoxy adhesive (EA) and the composite of epoxy adhesive having unfunctionalized 3DG. The addition of unfunctionalized 3DG to epoxy adhesive before curing causes the Tg of the epoxy adhesive to increase by about 4.4 °C. The presence of unfunctionalized 3DG in the epoxy adhesive matrix may be restricting the polymer chain movement thereby leading to a higher Tg. The curing onset of the composite material having polymer and graphene-containing material occurs at a higher temperature because the composite material needs more energy to overcome the hindrance of 3DG that is dispersed throughout the polymer matrix. The Tg is increased by reinforcing the polymer matrix and restricting the chain movement. The Tg is basically from soft state to glassy state, so the process of transitioning to glassy state is dependent on energy, but the presence of 3DG in the polymer hinders the transition and thus more energy (i.e., higher temperature) is needed.-75- LYT IP 134.P_LYTEP322WOTable 5. DSC of epoxy adhesive with and without unfunctionalized 3DGDescription Enthalpy Onset T Peak T Tg (J / g) (°C) (°C) (°C)Neat EA (No 3DG) 388.4 54.7 95.2 107.8 EA with unfunctionalized 3DG 328.9 61.9 104.2 112.2

[0170] In one approach, in a polymer formulation without added graphenecontaining material, the polymer chains are fully mobile, there is no obstruction and no barriers, so the crosslinking reaction happens uninhibited leading to a higher enthalpy change. 3DG may influence the behavior of the curing process, 3DG acts as a physical restrictor reducing the chain mobility and segmental motion. 3DG is not a part of the polymer network (i.e., 3DG is not chemically or covalently bonded to the polymer).3DG does not interact chemically with the polymer network.

[0171] MECHANICAL STRENGTH AND TOUGHNESS OF EPOXY ADHESIVE INCLUDING PRISTINE CARBON

[0172] In some approaches, the graphene morphologies play different roles in response to temperature as an external stimulus on the composite. For example, at lower temperatures under the Tg of the composite, the nodular graphene absorbs energy provided by the higher temperature and the composite remains in a glassy state at higher temperatures as demonstrated by change to a higher Tg of the composite material in the presence of pristine carbon. At higher temperatures, above the Tg, and the composite material is more ductile, rubbery, viscous, etc. the presence of the flaky graphene may enhance the mechanical strength of the composite material. One graphene material, i.e., a pristine carbon having a mixed morphology of nodular and flaky morphologies, dispersed in a composite polymer material provides improved toughness (as measured by increased applied energy to fail) and improved mechanical strength (as measured by increased force to fail) to a composite polymer material.

[0173] According to one aspect, an epoxy adhesive composite material including pristine carbon (i.e., unfunctionalized 3DG) has increased mechanical strength and increased peel strength (i.e., toughness). In one approach, at elevated temperature, e.g.,-76- LYT IP 134.P_LYTEP322WOabout 90 °C or higher, composite material having polymer and graphene-containing material having nodular and / or flaky morphologies have a mechanical strength in terms of lap shear strength at least 4% higher than a mechanical strength of the polymer in absence of the graphene-containing material. In one approach, a composite material has a mechanical strength, in terms of tensile lap shear strength, which is at least 5% higher than the polymer in absence of the graphene-containing material. Table 6 refers to TLSS of adhesive on aluminum substrate measured at room temperature.Table 6. TLSS of adhesive with and without unfunctionalized 3DG on aluminum substrateDescription TLSS (psi) St dev (%) Neat EA (No 3DG) 5,581 3.6EA with unfunctionalized 3DG 5,920 1.8

[0174] Toughness and ability to maintain bending stiffness and plasticity of an epoxy adhesive may be tested with peel strength that measures the resistance of an adhesive bond to peeling forces, which is crucial for ensuring structural integrity, durability, and safety. High peel strength enhances fatigue resistance, impact absorption, and environmental safety. Table 7 lists the results of a Floating roller peel conducted with the epoxy adhesives tested as per ASTM D3167. Adherends are 2024-T3 AlClad peeling skin and backing skin with aluminum treated with phosphoric acid anodize. Both epoxy adhesives, Neat EA and EA with unfunctionalized 3DG demonstrated comparable FR peel strengths.Table 7. Peel Strength of adhesive with and without unfunctionalized 3DG Description FR peel strength St dev (%)(Ib / in)Neat EA (No 3DG) 76.5 12.7EA with unfunctionalized 3DG 76.1 8.8

[0175] In one approach, a composite material has an even cohesive failure at a T-peel strength that is about equal to the polymer in absence of the graphene-containing-77- LYT IP 134.P_LYTEP322WOmaterial (3DG). The composite material is configured to be evenly distributed on surfaces positioned on opposite sides of the composite material after failure. FIG. 6 is an image of neat epoxy adhesive (EA) (upper peel test) compared to EA with unfunctionalized 3DG (lower peel test). Table 7 lists the values for floating roller peel strength of each sample and Table 8 lists the values for the T-Peel test. Both samples, neat EA and EA with unfunctionalized 3DG demonstrated comparable peel strengths in each test. Moreover, the samples of EA with unfunctionalized 3DG (bottom panels) shows overall cohesive failure, whereas the samples with the neat formulation of EA (without 3DG) shows some patches of adhesive failure.Table 8. T-Peel strength of adhesive with and without unfunctionalized 3DG Description T-Peel strength(Ib / in)Neat EA (No 3DG) 54.7EA with unfunctionalized 3DG 55.7

[0176] Mechanical strength of an epoxy adhesive composite may be measured with tensile lap shear strength tests. In one approach, epoxy adhesive having unfunctionalized 3DG demonstrated increased lap shear strength (LSS) representative of lap shear adhesion for composite fiber reinforced plastic (CFRP) bonding at elevated temperatures. For example, as listed in Table 9, epoxy adhesive (EA) with unfunctionalized 3DG demonstrated increased LSS compared to neat EA at 90 °C. EA with 3DG performed 4.5% better than its neat counterpart (Neat EA). The increasing trend in Tg is translated to its lap shear strength performance on CFRP when tested at 90 °C.Table 9. LSS on CFRP panels with of epoxy adhesive with and without unfunctionalized 3DG at 90 °C-78- LYT IP 134.P_LYTEP322WOTg Tested at 90 °C Description (°C)LSS (psi) LSS (MPa)Neat EA (No 3DG) 107.8 2,251 15.5 EA with unfunctionalized 112.2 2,347 16.2 3DG

[0177] According to one aspect, a composite material includes a polymer and 3DG. In preferred approaches, the polymer is an epoxy resin. In one approach, the composite is an epoxy adhesive having 3DG dispersed homogenously, uniformly dispersed, etc. throughout the epoxy adhesive resin. The epoxy adhesive resin is a polymer matrix. In preferred approaches, the 3DG is unfunctionalized 3DG.According to one aspect, an epoxy adhesive system (EA 3DG) demonstrates a theoretical glass transition temperature (Tg) higher than conventional commercially available adhesives. The elevated Tg of the adhesive polymer matrix is likely due to the presence of nodular graphene that functions as an energy well in the polymer matrix and absorbs energy. At higher temperatures, e.g., at the Tg of the polymer matrix without nodular graphene, the polymer matrix transitions from a glassy phase to a ductile phase. In sharp contrast, at higher temperatures for a polymer composite having a polymer matrix with nodular graphene, the energy applied at the higher temperature is absorbed at the energy wells formed by the nodular graphene and the polymer composite remains in the glassy state. A higher Tg for a polymer composite having graphene is evidence that the polymer composite has an ability to absorb energy better than a polymer composite without graphene, and the presence of nodular graphene and the formation of energy wells in the polymer composite may be responsible for the ability of the polymer composite having nodular graphene to absorb energy.

[0178] As shown in FIG. 7, a plot of heat flow measurements in DSC testing up to 180 °C of different adhesive formulations illustrates the composite of epoxy adhesive having unfunctionalized 3DG (EA 3DG) has the highest Tg, midpoint type being a half height midpoint of 112.98 °C when the adhesive is fully cured, where Tg is the temperature at which the heat flow plot shows a midpoint within the sloped region of-79- LYT IP 134.P_LYTEP322WOthe glass transition. The two commercially available structural adhesive formulations Ad 1 and Ad 2, tested under the same conditions being fully cured, had lower Tg as illustrated by a half height midpoint of 53.9 °C and 90.83 °C, respectively.

[0179] According to one aspect, a composite material that includes a polymer and 3DG has enhanced mechanical strength at elevated temperatures. In some approaches, the composite material has a mechanical strength above 5 MPa at a temperature above room temperature, above 80 °C, above 85 °C, above 90°C, above 95 °C, above 100 °C, etc. In some approaches, a composite material has a mechanical strength above 7.5 MPa, 10 MPa, 12.5 MPa, 15 MPa, etc. at a temperature above 80 °C, 85 °C, 90 °C, etc. A value of mechanical strength may be an absolute value based on several tests of mechanical strength of a composite material. In preferred approaches, the mechanical strength represents tensile lap shear strength of the composite material.

[0180] In preferred approaches, the composite material is an epoxy adhesive having 3DG dispersed uniformly throughout the epoxy matrix. According to one approach, the composite material is an adhesive that is configured to adhere to an adherend where the composite material is applied to and bonds to an adherend. An adherend is the surface, material, etc. to which ad adhesive is applied to create a bond. For example, adherends include surfaces of metal, plastic, wood, paper, biological materials, etc.

[0181] In applications of the composite adhesive material adhering to polymer materials or amorphous materials that have glass transition temperature (Tg), the Tg of the adhesive is higher than a Tg of the adherend. In some approaches, at higher temperatures, the adherend is affected by the temperature before the adhesive is affected by the temperature. The adhesive maintains bond strength at elevated temperatures that may be higher than the Tg of the adherend.

[0182] In various approaches, the epoxy adhesive system applied to different adherends has enhanced mechanical strength at elevated temperatures. In preferred approaches, the epoxy adhesive system is capable of anchoring on very dissimilar surfaces of adherends, such as a polymer material, metal, carbon fiber reinforced polymer, etc. In some approaches, the composite adhesive material may be configured to bond a first material to a second material, where the first and second materials have-80- LYT IP 134.P_LYTEP322WOdifferent compositions. For example, the composite adhesive material may bond a polymer material to a metal material. In one approach, a polymer material such as nylon may be an adherend for the epoxy adhesive. In another approach, a metal such as aluminum may be an adherend for the epoxy adhesive. In other approaches, the epoxy adhesive may be used on mixed materials. For example, the epoxy adhesive functions to bond a nylon adherend to an aluminum adherend, a nylon adherend to a CFRP adherend, a CFRP adherend to an aluminum adherend, etc.

[0183] In one approach, the epoxy polymer system demonstrates mean shear strength performance on an aluminum substrate (Al-Al) at 90 °C and 110 °C. As shown in FIG. 8 and Table 10. At 90 °c, the epoxy polymer system (EA 3DG) demonstrated excellent bond strength on the aluminum substrate compared to commercial epoxy adhesive products (Commercial Ad 1 and Commercial Ad 2). In particular, EA 3DG demonstrated a greater than 111% increase in bond strength over Commercial EA 1 and a greater than 23% increase in bond strength over Commercial Ad 2. At the higher temperature of 110 °C, EA 3DG demonstrated decreased bond strength compared to bond strength at 90 °C, but the bond strength of EA 3DG was still comparable to bond strength of Commercial Ad 1 at 90 °C. The curing conditions for each adhesive may vary. The epoxy polymer system EA 3DG 1 may be cured at 80 °C for 1 hour. Commercial Ad 1 was cured at 65 °C for 2 hours and Commercial Ad 2 was cured at 65 °C for 1 hour. Commercial Ad 1 and 2 are common commercially available structural adhesive formulations used as a benchmark of adhesive performance.Table 10: Al-Al Bonding Strength of Adhesives at Elevated TemperaturesShear Shear St dev TestFormulation Substrate Strength strength (%)Temperature(MPa) (psi)Commercial Ad 1 Al 90 °C 7.7 1120 9.1Commercial Ad 2 Al 90 °C 13.3 1930 8.0EA 3DG Al 90 °C 16.3 2366 7.0-81- LYT IP 134.P_LYTEP322WOEA 3DG Al 110 °C 7.4 1075 16.6

[0184] In one approach, the epoxy polymer system demonstrates mean shear strength on a carbon fiber reinforced polymer (CFRP-CFRP) substrate at room temperature and at elevated temperatures. As shown in FIG. 9 and Table 11, an epoxy polymer system (EA 3DG) demonstrates significant shear strength on a CFRP substrate at room temperature comparable to commercial epoxy adhesive products (Commercial Ad 1 and Commercial Ad 2). At elevated temperatures of 90 °C and 110 °C, epoxy polymer system (EA 3DG) demonstrates shear strength on CFRP substrate. Cure conditions for EA 3DG included 80 °C for 1 hour.Table 11: CFRP-CFRP Bonding Strength of Adhesives at RT and Elevated TemperaturesShear ShearTest St dev Formulation Substrate Strength strength Temperature (%)(MPa) (psi)Commercial Ad 1 CFRP RT 27.3 3958 9.1 Commercial Ad 2 CFRP RT 18.7 2712 9.6 EA 3DG CFRP RT 23.8 3450 18.4EA 3DG CFRP 90 °C 18.2 2644 3.7EA 3DG CFRP 110 °C 11.0 1602 8.7

[0185] In some tests, a nylon surface may demonstrate substrate failure, where the nylon surface may fail before the adhesive fails. A thickness of a substrate surface such as nylon surface may determine the substrate failure in adhesive applications. For example, in some applications, a nylon adherend having a certain thickness may be less likely to fail during adhesive applications compared to a nylon adherend having a smaller thickness.

[0186] In one approach, epoxy polymer system functions as an adhesive between multiple materials. For applications where EA 3DG is cured at 80 °C for one hour,-82- LYT IP 134.P_LYTEP322WObond strength of EA 3DG on a nylon-nylon substrate demonstrates a greater than 5 MPa lap shear strength before substrate failure, and for CFRP-nylon substrate, EA 3DG demonstrates a greater than 7 MPa lap shear strength before substrate failure. Delamination is not demonstrated in either application. Nylon 3-printed coupons used as adherends experience greater than 5x the load when stressed in tensile lap shear, so the nylon coupons fail before the adhesive fails.

[0187] SILICON- AND / OR NITROGEN-FUNCTIONALIZED CARBON

[0188] Aspects include functionalizing surface treatments for carbon (e.g., CNTs, CNO, graphene, 3D carbon materials such as 3D graphene) utilizing plasma reactors (e.g., microwave plasma reactors, fluid bed reactors, etc.) described herein. Various aspects can include in situ surface treatment during creation of carbon materials that can be combined with a binder or polymer in a composite material. Various aspects include functionalization of 3DG with silicon, and, in some approaches, functional izalion of 3DG with silicon and nitrogen. Various aspects can include surface treatment after creation of the carbon materials while the carbon materials are still within the reactor.

[0189] In various aspects, a population of carbon allotropes (e.g., pristine carbon, functionalized carbon, 3DG, etc.) may be generated to optimize function of specific thermoplastic materials. In one aspect, doping 3DG particle in situ - in the same reactor - generates Si- or Si-N-doped 3DG to optimize mechanical strength of structural epoxides and / or epoxy adhesives. The Si- or Si-N-doped 3DG may be characterized as being 3DG particles decorated with silicon or silicon and nitrogen, respectively. In some approaches, 3DG is generated and referred to as “exotic 3DG” having a functionality of interest for a desired outcome in mechanical and physical properties.

[0190] According to one aspect, an application of Si-doped 3DG and / or Si-N-doped 3DG having specific morphology enhances mechanical properties of a structural epoxy system. The decoration process of 3DG with silicon or silicon / nitrogen may be tuned to generate Si-3DG and / or Si-N-3DG particles having specific morphological features that correlate with enhancement of mechanical properties of a structure epoxy system. In one approach, silanol (Si-OH)-83- LYT IP 134.P_LYTEP322WOfunctionalities on the surface of Si-3DG particles allow the Si-3DG particles to become an integral via a chemical reaction between the silanol functionalities and the epoxy ring of the epoxy network via silane condensation.

[0191] According to one aspect, precursors added to the plasma reactor may include carbon and silicon material for forming 3DG decorated with silicon atoms. Further details regarding synthesis of silicon-doped or silicon and nitrogen-doped 3DG where 3DG is decorated with silicon and nitrogen atoms using a plasma reactor can be found in U.S. Patent No. 11,998,904, filed July 27, 2022, titled “FLUIDIZED BED REACTORS FOR POST-PROCESSING POWDERED CARBON,” which is hereby incorporated by reference in its entirety. The process describes a system of post-processing carbon powders that includes a gas feed source for a gas such as methane gas (CH4) that may be combined with an arbitrary gas or fluid such as hexamethydisiloxane (HMSDO) and / or hexamethyldisilazane (HMDSN), a precursor that has both silicon and nitrogen in one molecule such that in the generated exotic 3DG, both silicon and nitrogen may be detected on the functionalized 3DG. The methodology for adding precursors to the plasma reactor via a fluidized bed the raw materials port and the gas input allows the addition of precursors to the plasma reactor.

[0192] Without wishing to be bound by any theory, the silicon atom anchors to the carbon or graphene lattice and that becomes an anchor for subsequent material, which in one case is acetonitrile for nitrogen-containing functional group, such as a primary amine. These precursors may be successful in forming a functionalized 3DG in epoxy systems because the amine has anchored onto the lattice graphene would be reactive toward the epoxide ring interaction. The order in which the precursors are added in the plasma reactor may be very varied and adjusted accordingly to generate a desired percent silicon and a percent nitrogen, if desired, in the functionalized 3DG.

[0193] Further details regarding how to achieve reactor output of specific mixed morphology, e.g., nodules, flakes, combination nodules and flakes, etc., is shown and described as pertains to a control system of tuning different residence paths for generating 3DG having predefined morphologies is disclosed in U.S. Patent No. 11,623,197, filed January 23, 2020, titled “COMPLEX MODALITY REACTOR FOR MATERIALS PRODUCTION AND SYNTHESIS,” which is hereby-84- LYT IP 134.P_LYTEP322WOincorporated by reference in its entirety. As described herein, microwave energybased processing of hydrocarbon gasses accommodates fine-tuned control of many of the temperatures in a micro wave plasma reactor. In various approaches, parameters of generating plasma plumes in a plasma reactor that follow a predefined residence path may be tuned for purposes of forming different predefined morphologies of 3DG particles having specific physical characteristics. Parameters such as shape, texture, flow, temperature, physical, chemical and / or other properties may be adjusted to produce functionalized 3DG particles having predefined morphologies.

[0194] A predominant morphological feature may be defined as the morphological feature that is present in greater than 80% of the features present in the population of the heteroatom-doped 3DG, where heteroatoms are known as any atom other than carbon or hydrogen within a molecule (e.g., oxygen, silicon, nitrogen, etc.). In one approach, the predominant morphological feature may be present in greater than 90% of the features present in a population of the heteroatom-doped 3DG. In yet another approach, the predominant morphological feature may be present in greater than 95% of the features present in a population of heteroatom-doped 3DG.

[0195] In one approach, the predominant morphological feature of a heteroatom-doped 3DG may be a flaky morphology. In another approach, the predominant morphological feature of a heteroatom-doped 3DG may be a nodular morphology that is synonymous with a structure having nodules. In another approach, the predominant morphological feature of a heteroatom-doped 3DG may be a combination of flaky and nodular morphologies. In some approaches, the predominant morphological feature of a heteroatom-doped 3DG is graphitic particles.

[0196] In various approaches, a heteroatom for doping 3DG may be an element that is selected to functionalize 3DG. In particular, the heteroatom is selected as an element that is not carbon or hydrogen. The selected element for doping may be selected for a specific application of the heteroatom-doped 3DG. For example, the heteroatom may be silicon for enhanced chemical reaction of 3DG with a polymer. In preferred approaches, the heteroatom may be silicon, nitrogen, etc. In some approaches, 3DG may be doped with a combination of different heteroatoms. In some approaches, 3DG may be doped with different amounts of silicon, and the silicon-doped 3DG have different morphologies corresponding to the amount of silicon in the-85- LYT IP 134.P_LYTEP322WOcompound. The final product of silicon-doped 3DG has silicon present in the lattice structure of the 3DG. Doping with silicon (e.g., up to 3 wt% Si) may provide additional opportunities for structural integrity of epoxide forms.

[0197] Doping 3DG with Si, N, etc. (i.e. Si-doping, Si-N-doping, heteroatomdoping, etc.) may include tuning the plasma reactor with predefined parameters of the process such as: different inert nitrogen gas flow rates, different methane (CH4) gas flow rates, addition of different amounts of select precursors as alternate silicon sources (e.g., other than HMDSO, HMDSN, BDMADMS, etc.), adjustment of a ratio of precursors relative to each other / or and input gas (e.g., methane, etc.), adjustment of timing of the addition of the precursors, adjusting the power, etc. Each residence path may be associated with a different morphology of the formed heteroatom doped-3DG particle. The resulting heteroatom doped-3DG may have different morphological features corresponding to the predefined parameters of the process of forming the doped-3DG.

[0198] Processes for silicon doping include silanyl, siloxane, ring-opening epoxides, etc. Functionalized 3DG may utilize alternate silicone sources (other than HMDSO), e.g., (HMDSN, BDMADMS, etc.). Postprocessing doping of silicon-doped 3DG with nitrogen, amine, thiol, etc. may provide nucleophilic groups to bond with the epoxy resin and improve crosslinking (and thus strength).

[0199] SILICON- AND / OR NITROGEN- FUNCTIONALIZED CARBON FOR EPOXY ADHESIVE COMPOSITES

[0200] In some aspects, Si-and N-doped carbon (i.e., functionalized 3DG) were generated with HMDSO and acetonitrile precursors as exotic 3DG to augment mechanical strength to epoxide materials. In one approach, an HMDSO precursor is added with an acetonitrile precursor where the HMDSO provides a silicon anchor on the 3DG for the nitrogen atom provided by the acetonitrile. The exotic 3DG particles are generated from a plasma reactor as described herein as a ready-to-use functionalized 3DG particle. In preferred aspects, exotic 3DG particles do not undergo further post-production processes to acquire functionalization. A significant advantage of synthesis of exotic 3DG particles is the ability to scale-up production of specific exotic 3DG particles for various applications. During synthesis of 3DG,-86- LYT IP 134.P_LYTEP322WOprecursors vaporize within the plasma reactor for forming the exotic 3DG particles to bring out the desired functionality necessary for mechanical property enhancement.

[0201] According to various approaches, 3DG may be functionalized with nitrogen using various sources of nitrogen. In one approach, functionalizing the 3DG using a silane coupling agent, such as (3-aminopropyl)triethyoxysilane (APTES) solution, resulting in an amine-functionalized 3DG (3DG-NH2). In another approach, 3DG may be formed in the reactor and functionalized using acetonitrile (methyl cyanide, MeCN), with and without hexamethyldisiloxane (HMDSO). HMDSO enters the carbon lattice of the 3DG particles and acetonitrile modifies the 3DG particles with nitrogen to form a nitrogen-modified 3DG. In the plasma reactor, formation of 3DG-MeCN (Amine28) may include addition of MeCN in lower injection port, and formation of 3DG-HMDSO / MeCN (Amine29) may include addition of HMDSO in laminar plus MeCN in lower injection port.

[0202] In one approach, the amine-functionalized graphene includes oxygen, the oxygen being substantially associated with silicon as a silicon oxide compound. In another approach, the silicon oxide compound may be localized on an outer edge of carbon nodules defining the amine-functionalized graphene. FIGS. 10A-10D depict TEM-EELS (transmission electron microscopy - electron energy loss spectrophotometry) images of silicon-doped amine-functionalized 3DG (HMDSO / MeCN, Amine29). FIG. 3A includes an image of a portion of the amine-functionalized 3DG in part (a), and the same image in part (b) where elements carbon, oxygen, and silicon are identified. The image depicts mostly graphitic particles having clusters of oxygen and silicon associated with the graphitic particles.

[0203] Parts (a) and (c) of FIG. 10B illustrate a more nodular morphology of a portion of an amine-functionalized 3DG having a more uniform distribution of silicone and oxygen throughout the carbon material. The TEM-EELS elemental analysis magnified view in parts (b), (d), and (e) of FIG. 10B illustrate the localization of silicon in the center of the carbon nodule with silicon and oxygen localized on the outer edge of the carbon nodules.

[0204] FIG. 10C illustrates a different views, parts (a) and (c), of a portion of an amine-functionalized 3DG having primarily nodular morphology. The TEM-EELS-87- LYT IP 134.P_LYTEP322WOelemental analysis indicates possible silicon oxygen compounds localized on the outer edges of the carbon nodules, parts (b) and in a magnified view in part (d).

[0205] FIG. 10D part (a) illustrates an edge view of a portion of a graphitic particle of the amine-functionalized 3DG. TEM-EELS elemental analysis of a magnified view of a section (from the inset box on part (a)) of the edge portion where oxygen atoms and silicone atoms are localized on the outer edges of nodular carbon features, part (b). Part (c) is a further magnified view of the elemental analysis of a nodule associated with the 3DG particle and depicts silicon-oxygen compounds associated within the carbon.

[0206] Table 12 lists the metrological data associated with amine-functionalized 3DG that may be used in an application for enhancing epoxy adhesive. Analysis of SEM images of the amine-functionalized 3DG show that sample Amine28 and Amine 35 have a predominant morphology of flakes, and samples Amine29 and Amine36 have a predominant morphology of a combination of flakes and nodules. In some approaches, the amine-functionalized 3DG may have a surface area in a range of 50 to 300 meter squared per gram (m2 / g), or 50 to 200 m2 / g, or 50 to 100 m2 / g, or 100 to 200 m2 / g, or 100 to 300 m2 / g. In preferred approaches, the amine-functionalized 3DG samples have a surface area in a range of about 100 to 200 m2 / g. In one approach, the amine-functionalized graphene has a similar layer thickness of graphene. In various approaches, the amine-functionalized graphene may have a D / G ratio of Raman band intensities (i.e., ID / IG) in a range between 0.3 to 1.0, or 0.3 to 0.8, or 0.3 to 0.6, or 0.4 to 1.0, or 0.4 to 0.8.

[0207] The synthesis process of Amine29 and Amine36 results in significantly higher %Si and %N as measured by XPS. Amine29 is generated in the presence of HMDSO, a source of silicon, and acetonitrile, a source of nitrogen thereby providing greater sources of silicon and nitrogen for the Si- and N-doped 3DG.

[0208] Without wishing to be bound by any theory, it is believed that the higher amount of silicon helps the addition of nitrogen on graphene surface, leading to 0.93 % to 1.31% in the Amine29 samples as seen from XPS. The presence of nitrogen in different functional forms in amine-functionalized 3DG (Amine29) results in betterLYT IP 134.P_LYTEP322WOdispersibility and less aggregates in the mixture. This consequently may lead to better mechanical performance.-89- LYT IP 134.P_LYTEP322WOTable 12: Metrology data of amine-functionalized 3DGAnalysis Amine28 Amine29 Amine35 Amine36HMDSO + Replica of Replica of Description MeCNMeCN Amine28 Amine29 Flakes & Flakes & SEM image Flakes Flakesnodules nodules SSA (m2 / g) 157.4 157.3 139.4 153.7 XRF Light elements 99.84 91.88 99.4 93.38 XRF Si 0.13 8.08 0.57 6.62D / G (area) 1.27 1.13 0.77 0.99D / G (area) 0.54 0.6 0.58 0.65D / G (intensity) 0.39 0.42 0.42 0.45La (nm) 36.2 32.1 33.7 29.4XRD # Layer 10.8 10.0 9.8 9.7IGA-0 0.135 0.058 0.091 0.047SEM- Si (at%) 0.00 4.86 0.00 4.21 EDS 0 (at%) 2.63 9.09 1.95 5.61Si % 0.00 4.42 0.12 4.84 XPS 0 % 1.09 5.67 0.39 4.60N % 0.00 0.93 0.30 1.31Amine35 is a replica run of Amine28, Amine36 is a replica run of Amine29

[0209] MECHANICAL STRENGTH OF EPOXY ADHESIVE INCLUDING FUNCTIONALIZED CARBON-90- LYT IP 134.P_LYTEP322WO

[0210] Epoxy adhesives are used in automotive and aerospace industries with a high margin. Tensile lap shear strength (TLSS) is one of the key factors in determining the mechanical properties of adhesives. It is desirable to enhance mechanical characteristics of epoxy adhesive to achieve very high performance in aerospace applications. 3DG particles decorated with amine functionalities, via silane anchors on 3DG particles, are designated as Amine29. The presence of amine functionalities on 3DG enhances the dispersibility of 3DG in the hardener, which is a mixture of different amines. The smaller particle size of amine-functionalized 3DG, and hence minimized surface energy that has better compatibility within the epoxy network, enhances dispersion of the 3DG in the adhesive epoxy thereby leading to better mechanical performance of the epoxy adhesive.

[0211] As described herein, epoxy adhesives are combined with carbon (e.g., CNTs, CNO, graphene, 3D carbon materials such as 3D graphene) that are functionalized utilizing plasma reactors (e.g., microwave plasma reactors). Various aspects may include in situ surface treatment during creation of carbon materials that can be combined with a binder or polymer in a composite material. Various aspects include functionalization of 3DG with silicon, and nitrogen in some approaches. Various aspects may include surface treatment after creation of the carbon materials while the carbon materials are still within the reactor.

[0212] TWO PART EPOXY ADHESIVE INCLUDING FUNCTIONALIZED 3DG

[0213] According to one aspect, an epoxy adhesive (EA) is loaded with a functionalized graphene and forms a composite material that demonstrates improved mechanical properties compared to an epoxy adhesive without graphene. An epoxy adhesive, having components combined as described herein, or a commercially available aerospace grade 2-part epoxy adhesive system loaded with functionalized graphene demonstrate enhanced mechanical properties.

[0214] 3DG has a structure that may be more compatible with thermoset epoxy polymers. According to various aspects, an amine-functionalized 3DG may be added to an epoxy adhesive to augment the mechanical properties of the epoxy adhesive. Adhesive epoxy adhesive functions as a glue between to materials, such as metal to-91- LYT IP 134.P_LYTEP322WOmetal, metal to composite substrate, etc. Addition of 3DG to an epoxy adhesive may elevate durability such that the adhesive has improved lasting strength over time under heat, pressure, environmental stress, etc. According to one aspect, a composite material includes an epoxy adhesive and an amine-functionalized graphene. The epoxy adhesive loaded with amine-functionalized graphene has a mechanical strength that is at least 5% higher than a mechanical strength of the epoxy adhesive in the absence of amine-functionalized graphene. In a preferred approach, the amine-functionalized graphene is an amine-functionalized 3DG.

[0215] In one approach, an epoxy adhesive system for loading amine-functionalized graphene is configured to be formed from a 2-part epoxy adhesive system (Part A and Part B). Part A may be a mixture of epoxies with a thixotropic agent and Part B known as the hardener component includes amines, hardeners, etc. Upon mixing of Part A and B, the resulting epoxy adhesive hardens over time.Addition of 3DG to Part B of an epoxy adhesive may enhance the hardening process. In one example of a two-part epoxy adhesive, Part A of epoxy adhesive may include bisphenol A 30-60% diglycidyl ether (BADGE), 10-30% 4-4’ -methylenebi s (N,N-diglycidylaniline) (MGDGA), 10-30% poly(bisphenol-A-co-epichlorohydrin, and 5-10% hydrophilic SiO2 (glass), 1-5% hydrophobic SiO2-PDMS. In addition. Part A may include 1-5% GP-TMS. Part B of epoxy adhesive, known as the hardener component, may include 30-60% l,4-bis(3-aminopropyl)piperazine (BAPP), 5-10% hydrophilic SiO2 (glass), 1-5% benzyl alcohol (a diluent to promote curing), 1-5% phenol, 1-5% 3-aminomethyl-3,5,5-trimethylcyclohexylamine (AMTMCHA), 1-5% 3,3’-oxybis(ethyleneoxy)bis(propylamine) (APDEG), and 1-5% N-aminoethylpiperzaine (NAEP).

[0216] In one approach, various types and loadings of 3DG may have different effects on the performance of a product epoxy adhesive of a 2-part epoxy adhesive system. In one example, after establishing a baseline of neat epoxy adhesive Part A and B, various types and loadings of 3DG were screened in the formulation to identify a functionalized 3DG having optimal performance-enhancing properties in a 2-part epoxy adhesive. In a preferred approach, functionalized 3DG is added to Part B. Amine-functionalized 3DG may be synthesized using different methods of-92- LYT IP 134.P_LYTEP322WOfunctionalization, as described herein. Commercially available epoxy adhesive formulations do not include graphene.

[0217] In preferred approaches, amine functionalization of 3DG allows enhanced dispersion of amine-functionalized 3DG in the amine mixture of Part B of the epoxy adhesive system. Moreover, a smaller particle size of amine-functionalized 3DG may allow the enhanced dispersion of amine-functionalized 3DG in the epoxy adhesive that leads to better mechanical performance. The small particle size of the amine-functionalized 3DG may minimize surface energy of the 3DG particles and thus enable better compatibility of the 3DG particles within the epoxy network.

[0218] In some approaches, amine-functionalized 3DG may be synthesized in a plasma reactor that includes specific amine and silicon precursors. In one approach, an amine-functionalized 3DG, designated as Amine28, is a 3DG synthesized in a plasma reactor with acetonitrile included as a functional additive. In another approach, an amine-functionalized 3DG, designated as Amine29, is a 3DG synthesized in a plasma reactor with acetonitrile and hexamethydisiloxane (HMDSO) included as functional additives. In another approach, amine functionalization of 3DG results in a 3DG molecule decorated with amine functionalities via silane anchors.

[0219] In a preferred approach, a small amount of amine-functionalized 3DG may be added to Part B, the amine hardener, of a 2-part epoxy adhesive. In preferred approaches, the graphene is present in an amount that is detectable in the adhesive using metrology techniques. The epoxy adhesive is a composite material of Part A plus Part B. Moreover, graphene is present in an effective amount in the amine hardener to cause a perceivable increase in the lap shear strength of the epoxy adhesive. In one approach, an amount of amine-functionalized graphene added to an amine hardener (Part B) is in a range of greater than 0.01 wt% to about 5 wt %, or 0.01 wt% to about 2 wt%, or 0.01 wt% to about 1 wt%, or 0.01 wt% to 0.5 wt%, or 0.01 wt% to 0.2 wt%, or 0.05 wt% to about 5 wt %, or 0.05 wt% to about 2 wt%, or 0.05 wt% to about 1 wt%, or 0.05 wt% to 0.5 wt%, or 0.05 wt% to 0.2 wt%, 0.1 wt% to about 5 wt%, or 0.1 wt% to about 2 wt%, or 0.1 wt% to 1 wt%, or 0.5 wt% to 5 wt%, or 0.5 wt% to 2 wt%, or 0.5 wt% to 1 wt%, etc. of the total weight of the composite material, the epoxy adhesive having a total combined weight of Part A plus Part B. In a preferred approach, an amount of amine-functionalized graphene added to-93- LYT IP 134.P_LYTEP322WOan amine hardener (Part B) is in a range of greater than 0.01 wt% to about 0.2 wt % of the total weight of the epoxy adhesive. The amine-functionalized 3DG is uniformly dispersed in the epoxy adhesive.

[0220] In preferred approaches, the amine-functionalized graphene is uniformly dispersed in the epoxy adhesive. FIG. 11 illustrates an improved dispersion of amine-functionalized 3DG in an epoxy adhesive (EA). Part (a) is an image of samples of amine-functionalized 3DG in Part B (upper row) and the cured epoxy 2-part adhesive (lower row). The upper panels illustrate a magnified view of the dispersion of amine-functionalized 3DG in Part B of the two-part pre-cured epoxy adhesive, Amine28 (b) and Amine29 (d). There is slightly better uniform dispersion of aininc-lunclionalizcd 3DG in Amine29 (d). The lower panels illustrate a magnified view of the dispersion of amine-functionalized 3DG in cured epoxy adhesive composite material, Amine28 (c) and Amine29 (e). After curing, there is less visible particles in the Amine29 cured mixture (e).

[0221] The 2-part epoxy adhesive system is assessed to optimize the components in the adhesive system. As demonstrated in the assessments that follow, components may be varied in Part A or Part B and the resulting epoxy adhesive tested for Tensile Lap Shear Strength (TLSS) using a controlled method to test adhesive performance. In some approaches, metal panels are laid out such that only the edge of an aluminum panel is aligned with another panel. The adhesive is mounted on the other side of the panel. The force is measured at complete breakage of the part. Tensile lap shear strength (TLSS) is a measure of an adhesive’s strength and how well a bonded joint will hold up over time. This test is performed on all formulations, including the commercial EA as a baseline to determine the performance difference. A set of 5 specimens was prepared on 2024-T3 AlClad aluminum treated with phosphoric acid anodize per ASTM D3933 and tested according to ASTM D1002.

[0222] In one approach, an epoxy adhesive loaded with amine-functionalized 3DG has a lap shear strength that is at least 5% higher than a lap shear strength of the epoxy adhesive in the absence of aininc-lunclionalizcd graphene. When compared to commercial EA, epoxy adhesive 1 (EA 1) including 3DG performs about an average of 5 - 10% better in tensile lap shear strength (TLSS). Specifically, showed the most promising results, outperforming the commercial EA by 6 - 7%, as shown in FIG. 12.-94- LYT IP 134.P_LYTEP322WOTable 13 lists the tensile lap strength results of amine-functionalized epoxy adhesive formulation illustrated in FIG. 12. In a preferred approach, a fraction of amine-functionalized 3DG mixed into a base epoxy adhesive results in improved tensile lap shear strength.Table 13. The Effect of Different Amine-functionalized 3DG on Epoxy Adhesive Description TLSS St dev % Improvement psi (%) Over Commercial Commercial EA* 5,572 2.6 -EA 1 without 3DG 4,787 5.1 (+ 2.8) APTES-3DG (NH2-3DG) 5,254 4.1 (+ 3.1) Amine28 5,958 6.2 + 6.9 Amine29 5,912 4.5 + 6.1Accelerated curing conditions of epoxy adhesive included 82 °C for 1 hour.*Commercial aerospace grade 2-Part epoxy adhesive (Commercial EA).

[0223] In a same-day test, EA 1 demonstrated a modest increase in tensile lap shear strength over Commercial EA (Run 1, FIG. 12). In another same-day test, EA 1 having NH2-3DG demonstrated a modest increase in tensile lap shear strength over Commercial EA (Run 2, FIG. 12). The amine-functionalized 3DG using acetonitrile (MeCN) as a nitrogen source with HMDSO (Amine29) or without HMDSO (Amine28) demonstrated about a greater than 6% increase in tensile lap shear strength in the commercial EA (Run 3, FIG. 12 and Table 13). A comparison of the commercial EA with Amine28 and Amine29 to an average of the three runs of the commercial EA without 3DG (5,165 psi) demonstrates a greater than 10% increase in TLSS.

[0224] According to one approach, amine-functionalized 3DG demonstrates better performance in tensile lap shear strength compared to 2D graphene (GO and rGO). The results FIG. 13 and in Table 14 show a comparison of tensile lap shear strength (TLSS) of various epoxy adhesives including Commercial EA, Epoxy adhesive 1 (EA-95- LYT IP 134.P_LYTEP322WO1) and EA 1 with amine-functionalized 3DG using MeCN (Amine28) and HMDSO+MeCN (Amine29). These results were compared with EA 1 with 2D graphene oxide (GO) and reduced graphene oxide (rGO). Amine- func ionalized 3DG Amine28 and Amine29 demonstrated enhanced TLSS compared to commercial EA by greater than 6%. EA 1 without graphene demonstrated a remarkable strength having a high TLSS compared to the commercial EA. Epoxy adhesive having the platelet-like 2D graphene oxide components, GO and rGO, demonstrated diminished adhesive strength, noticeably decreasing the TLSS to only 1.2 % and less than 4.2%, respectively. These results demonstrated an advantage of 3DG over 2D graphene in epoxy adhesive.Table 14. Values of Tensile Lap Shear Strength (TLSS) of Tested Samples Description TLSS St dev % Improvementpsi (%) Over CommercialCommercial EA 5,572 2.6 -Amine28 5,958 6.2 + 6.9Amine29 5,912 4.5 + 6.1EA 1 5,976 5.6 + 7.2GO 5,638 10.8 + 1.2rGO 5,341 11.9 - 4.2

[0225] According to various aspects, 3D graphene-enhanced formulations have improved properties and performance compared to commercially available graphene additives, such as graphene oxide (GO) and reduced graphene oxide (rGO) and highlight the unique advantages of the invented 3DG. Commercial graphene oxides (GOs) and reduced graphene oxides (rGOs) have functional groups such as epoxy (-C-O-C-), carboxylic (-COOH) and hydroxy (-OH). Of these, hydroxy groups are the most nucleophilic and able to participate in epoxy ring opening reaction during curing process. On the other hand, amine-functionalized 3DG has more nucleophilic amine-96- LYT IP 134.P_LYTEP322WOfunctionality, which is better able to participate in the epoxy ring opening and become the part of the crosslinked network.

[0226] Each epoxy adhesive composite material, Commercial EA and EA 1, are made from two parts, Part A and Part B. The Commercial EA does not include graphene in either part. Epoxy Adhesive 1 (EA 1) has amine-functionalized 3DG in Part B. FIG. 7 and Table 15 illustrate an effect of graphene (3DG) present in Part B of the 2-part epoxy adhesive. The weight ratio of Part A:Part B in both systems is equal. Replacement of the commercial Part B with EA 1 Part B resulted in a greater than 5% improvement in tensile lap shear strength of the epoxy adhesive. This enhancement of tensile lap shear strength may be attributed to the presence of 3DG in the EA 1 Part B composition.Table 15. Comparison of Epoxy Adhesives: Tensile Lap Shear Strength (TLSS)Description TLSS St dev % Improvementpsi (%) Over Commercial Commercial EA 4,487 2.9 -Comm EA Part A / EA 1 Part B 4,715 4.0 + 5.1

[0227] In one approach, different nitrogen-functionalized 3DG were tested in epoxy adhesives for improved performance in TLSS. The N-functionalized 3DG were added to part B of the epoxy adhesive system at a loading of 1 wt% for a total loading equal to 0.3 wt% in EA. The different N-functionalized 3DG included APTES-functionalized Si-doped 3DG (NH2-Si-3DG), HMDSN-functionalized Si-doped 3DG (Si52), NH3 -functionalized 3DG, lower port (Amine24), and NI L-lunclionalized 3DG, laminar port (Amine25). Table 16 lists the TLSS results of the composite samples. The commercially available aerospace grade 2-part epoxy adhesive (EA) was included for comparison. The APTES -functionalized Si-doped 3DG (NI L-Si-3DG) performed parity to the commercial EA. However, all the other N-functionalized 3DG did not perform well. Thus, the most desirable form of amine is a primary amine.Table 16. Different N-functionalized 3DG in Epoxy Adhesives: Tensile Lap Shear Strength (TLSS)-97- LYT IP 134.P_LYTEP322WODescription TLSS St dev % Improvementpsi (%) Over CommercialCommercial EA 5,493 7.7 -EA 1, NH2-Si-3DG 5,351 7.8 - 2.7EA 1, Si52 4,836 9.8 - 12.0E A 1 , Amine24 4,682 5.5 - 14.8EA 1 , Amine 25 4,736 18.2 - 13.8

[0228] In one approach, the loading of N-functionalized 3DG was varied to determine optimal loading in epoxy adhesive. Note the average lap shear strength of commercial EA varied day to day. The reported % improvement is based on the average performance of the commercial EA. The loadings of NH2-Si-3DG varied from 0.3 wt%, 1.0 wt%, and 3.0 wt%. Table 17 lists the TLSS results of the composite samples. There was a decreasing trend in TLSS with increasing amount of NH2-Si-3DG in part B of the epoxy adhesive system. EA 1 with 0.3 wt% NH2-Si-3DG led to 6.2% better TLSS than commercial EA. Compared neat EA 1 with no 3DG, using NH2-Si-3DG led to much improved performance, ranging from 4.2% to 15.9%.Table 17. Different amounts of N-functionalized 3DG in Epoxy Adhesives: Tensile Lap Shear Strength (TLSS)Description TLSS St dev % Improvement % Improvement psi (%) Over Over Commercial Neat EA 1Commercial EA 5,493 7.7 - -EA l, no 3DG 4,787 5.1 - 8.2 -EA 1, NH2-Si-3DG, 0.3% 5,548 8.4 + 6.2 + 15.9 EA 1, NH2-Si-3DG, 1.0% 5,351 7.8 + 2.6 + 11.8-98- LYT IP 134.P_LYTEP322WOEA 1, NH2-Si-3DG, 0.3% 4,990 8.4 - 4.3 + 4.2

[0229] In one approach, the ratio of silica to MGF (milled glass fiber) was varied in Part A of the 2-part adhesive system to understand the effect of the ratio on viscosity and toughness. Part B in this system included 1 wt% APTES-functionalized Silicon-doped 3DG (NH2-Si-3DG). Each sample included 5 wt% toughener carboxyterminated poly(butadiene-co-acrylonitrile (CTBA) in part A. The total organic content in part A was 9.4 wt%. Table 18 lists the TLSS results of the composite samples. The commercially available aerospace grade 2-part epoxy adhesive (EA ) was included for comparison. Although silica / MGF =1.5 showed slightly lower TLSS compared to silica / MGF = 9, the viscosity when mixed with Part B matched loser to the commercial EA. Moreover, fractured surface of TLSS specimens also showed surprising results, where the higher MGF loading led to similar failure mode (i.e., a rougher fractured surface with higher MGF loading) to the commercial EA. The epoxy adhesive having silica / MGF=1.5 in part A showed better toughness that leads to more cohesive failure in the TLSS test.Table 18. Variation of ratio of silica to MGF in Epoxy Adhesives having 3DG: Tensile Lap Shear Strength (TLSS)Description TLSS St dev % Improvementpsi (%) Over Commercial Commercial EA 5,493 7.7 - EA 1, silica / MGF = 9 5,227 9.7 - 4.9EA 1, silica / MGF = 1.5 5,114 4.2 - 6.9

[0230] In one approach, different adhesion promoters in part A were tested in the 2-part epoxy adhesive. All part A samples included a fixed ratio of fumed silica / milled glass fiber (MGF) = 1.5 and CTBA was removed since it negatively affected TLSS. Two adhesion promoters were tested: (3-glycidylpropyl)trimethoxysilane (GP-TMS) and (3,4-epoxycyclohexyl)ethyltrimethyoxysilane (ECH-TMS). Part B of each sample included APTES-functionalized Si-doped 3DG (NH2-Si-3DG) at 1 wt% loading.-99- LYT IP 134.P_LYTEP322WOTable 19 lists the TLSS results of the composite samples. The commercially available aerospace grade 2-part epoxy adhesive (EA) was included for comparison. The epoxy adhesive including the adhesion promoter GP-TMS performed slightly better than the epoxy adhesive including the adhesion promoter ECH-TMS. In addition, GP-TMS is a preferred adhesion promoter because there is better economic savings with GP-TMS compared to ECH-TMS.Table 19. Different Adhesion Promoters in Epoxy Adhesives having 3DG: Tensile Lap Shear Strength (TLSS)Description TLSS St dev % Improvementpsi (%) Over CommercialCommercial EA 5,493 7.7 -EA 1, GP-TMS 5,351 7.8 - 2.6EA 1, ECH-TMS 5,183 8.0 - 5.6

[0231] In one approach, the ralio of part A to part B in the epoxy adhesive system was tested for optimal TLSS measurement. The commercially available aerospace grade 2-part epoxy adhesive (EA) recommends 2.3 Part A:1 Part B weight ratio (100:43). The epoxy adhesive system (EA 1) with 0.3 wt% NH2-Si-3DG was formulated with increasing and decreasing weight ralio, an amine rich system at 2.0 Part A:1 Part B (100:50) and an epoxy-rich system at 2.6 Part A:1 Part B (100 to 38). Table 20 lists the TLSS results of the composite samples. Results of TLSS were measured for improvement over the Commercial EA. The epoxy adhesive EA 1 with decreased relative amount of Part A (2.0:1) and increased relative amount of Part A (2.6:1) showed decreased TLSS compared to the recommended ratio of Part A: ari B (2.3:1). Without wishing to be bound by any theory, it is believed that an epoxy rich system having greater amount of epoxy chains relative to amine associations results in defects of unassociated epoxy chains and dangling portions of epoxy chains. An amine rich system having a greater amount of amine-type molecules results in unassociated amines dispersed through the composite resulting in dangling portions of epoxy chain. In a preferred approach, a ralio Part A:Part B being 2.3:1 provides a-100- LYT IP 134.P_LYTEP322WOstoichiometric ratio that results in association of epoxy chains with amine molecules and a minimum of defects present in the epoxy composite.Table 20 The Effect of Part A:Part B RatioDescription TLSS St dev % Improvementpsi (%) OverCommercialCommercial EA 5,907 4.1 -A:B = 2.0 to 1 (100 to 50) 4,790 5.5 - 6.0A:B = 2.3 to 1 (100 to 43) 5,254 4.1 + 3.1A:B = 2.6 to 1 (100 to 38) 4,403 4.3 - 13.6

[0232] In one approach, addition of APTES -functionalized Si-doped 3DG (NH2-Si-3DG) is added preferably to Part B of a 2-part epoxy adhesive system. For example, a comparison of 0.3 wt% NH2-Si-3DG in Part A versus Part B of epoxy adhesive (EA 1) shows a slight increase in TLSS compared to commercial EA. Table 21 lists the TLSS results of the composite samples. Results of TLSS were measured for improvement over the Commercial EA. The presence of 3DG in Part A performed poorly, showing a 10% decrease in TLSS, and cohesive failure was observed.Table 21. The Effect of 3DG in Part A versus Part BDescription TLSS St dev % Improvementpsi (%) OverCommercialCommercial EA 5,036 2.6 -3DG in Part A 4,537 10.7 - 9.93DG in Part B 5,056 10.3 + 0.4-101- LYT IP 134.P_LYTEP322WO

[0233] THERMAL STABILZATION OF EPOXY ADHESIVE WITH FUNCTIONALIZED CARBON

[0234] A key issue that arises in the use of adhesives in a variety of industries such as aerospace, automative, etc. include maintaining a stably bonded adherence of components together under a high temperature range. At a higher temperature range, the adhesive progressively becomes less compliant, and the adhesive property is weakened thereby leading to problems in de-bonding that leads to catastrophic failure of the adhesive. As described herein, according to one aspect, high temperature stability and glass transition temperature (Tg) may be achieved without sacrificing other properties, and without resorting to more complicated or cost-ineffective methods. Epoxy adhesives typically have a Tg that strongly correlates to their cure temperature. Lower cure temperatures are desirable because these temperatures are easier to achieve. However, an epoxy adhesive having a higher Tg is also desired because it means the adhesive will perform better in high-temperature applications.

[0235] According to one aspect, addition of certain types of carbons may allow for the adhesive to retain stiffness and have a higher Tg. In a preferred approach, a functionalized 3DG dispersed in an epoxy adhesive allows the adhesive to retain mechanical strength and have a higher Tg. In optimal conditions, an epoxy adhesive having a higher Tg allows for higher environmental temperatures for operation of components adhered with the adhesive having a higher Tg without risk of adhesive failure. In one example, an epoxy adhesive having a higher Tg avoids the risk that operating temperatures near the Tg of conventional epoxy adhesive may cause a transition of the adhesive from glassy to rubbery thereby causing the material to warp and change its shape and dimensions.

[0236] Methods to raise the Tg of an adhesive product has not been a simple problem to resolve. Some reports to overcome the issue of adhesives performing at high temperatures have included curing the adhesive at higher temperatures, increasing specific components of the adhesive, etc. However, these approaches cause the adhesive to have decreased mechanical strength, e.g., become more brittle, less tough, etc. In one example, curing an epoxy adhesive at a higher temperature often involves complicated cure cycle. In another example, addition of specific thermal resistant components, such as thermally resistant fillers (e.g., 20-30% alumina-102- LYT IP 134.P_LYTEP322WOpowder) increases the density of the adhesive, often by as much as 1.5x, and thus the cost and weight of adhesive increases.

[0237] According to one aspect, addition of functionalized 3DG to an epoxy adhesive system causes the adhesive to have a higher Tg without the expense of any other physical properties. In a preferred approach, addition of functionalized 3DG at loadings below 1 wt% to an adhesive composition allows for an adhesive to have a higher Tg without increasing the cure temperature. Further, epoxy adhesive loaded with functionalized 3DG has an enhanced resistance to shear, as measured in terms of shear modulus. An enhanced resistance to shear will likely translate to better adhesive compliance under loads, at room and elevated temperature. As a value-proposition this gives us a unique advantage over other products on the market.

[0238] EDGE-FUNCTIONALIZED CARBON

[0239] Although allotropes of carbon, for example, graphene, nanotubes, nanoparticles, etc. may have a capability of establishing a reinforcing matrix within a resin material, the effects of different allotropes of carbon in epoxy adhesive is varied. In various approaches, adhesives including different allotropes of carbon may perform differently depending on the structure of the carbon. In one approach, different types of oxidized graphene that have heteroatoms associated with the oxidized graphene demonstrate improved adhesive properties. Defect sites with different atoms, specifically oxygen and nitrogen, may increase the compatibilization or increase the number of interactions between the carbon and the resin being an epoxy which means it will benefit form different hydrogen bonding that is also present in epoxy adhesives.

[0240] Table 22 lists the metrology data of the functionalized 3DG that may be added to epoxy adhesive composite material. Si96 is a reactor-synthesized Si-doped and N-functionalized 3DG using HMDSO and acetonitrile. Amine43 (i.e., exotic 3DG) is a reactor-synthesized 3DG that includes pyrrole as the only precursor in the reactor synthesis of 3DG. Graphene ball-milled (GBM) is reactor- synthesized 3DG that has been subjected to ball-milling with a planetary mixer to produce edge functionality on the 3DG panicles (i.e., edge-functionalized 3DG). Without wishing to be bound by theory, ball milling 3DG process to introduce defects to the graphene without introducing increasing detrimental amounts of oxygen.-103- LYT IP 134.P_LYTEP322WOTable 22: Properties of functionalized 3DGMaterial ID / IG Elemental % BET surface Layer count (IGA / XRF) area from XRD m2 / gSi96 0.51 90.1% C 165 10.0 0.4% N0.1% O7.0% SiAmine43 0.61 96.2% C 58 12.51.1% N0.5% OGBM 1.25 87.4% C 500 6.91.7% N7.4% O

[0241] The characteristics of the functionalized 3DG include estimation of defects (D / G ratio of Raman band intensities, ID / IG), element percentages, surface area, and layer count as listed in Table 22. In some approaches, the edge-functionalized 3DG has a physical characteristic of being formed using ball-milling. The physical characteristics may include increased surface area, higher D / G ratio of Raman band intensities, and fewer estimated graphene layers. The GBM material has a higher ID / IG ratio compared to Si96 and Amine43 indicali ng a greater incidence of defects in the graphene. The GBM has a higher surface area that is similar to a surface area of single layer graphene (Table 23). Essentially, the BET surface area analysis involves a measurement of the amount of liquid N2 absorbed by the carbon product as a function of the pressure difference as the liquid N2 is added to the system. In addition, the value of the surface area for each functionalized carbon may be used to estimate the relative particle size. For instance, a smaller particle sizes of a material correlates with a larger the surface area per unit volume of the material. Thus, the GBM material has smaller particle sizes compared to Si96 and Amine43. In some approaches, edge-functionalized 3DG (e.g., GBM) has a surface area greater than about 50 to 600 m2 / g, or 50 to 500 m2 / g, or 50 to 400 m2 / g, or 50 to 300 m2 / g, or 100 to 600 m2 / g, or 100 to-104- LYT IP 134.P_LYTEP322WO500 m2 / g, or 100 to 400 m2 / g, or 100 to 300 m2 / g, or 200 to 600 m2 / g, or 200 to 500 m2 / g, or 200 to 400 m2 / g, or 200 to 300 m2 / g, or 300 to 600 m2 / g, or 300 to 500 m2 / g, or 300 to 400 m2 / g, etc. In preferred approaches, edge-functionalized 3DG has a surface area greater than about 300 to 600 m2 / g. In some approaches, edge-functionalized 3DG has a D / G ratio of Raman band intensities in a range of about 0.50 to less than 2.00., or 0.50 to 1.50, or 0.50 to 1.00, or 1.00 to 2.00, etc.

[0242] Moreover, the GBM material has a smaller layer count compared to Si96 and Amine43. The layer count correlates to the light diffracted from a carbon particle that in turn is used to calculate the layer thickness of the particle. The purest graphene would be a single layer, however, achieving single layer is difficult. Graphene is typically less than 100 layers, whereas graphite is a carbon product having more than 100 layers. Ball-milling graphene reduces the layer count by grinding and exlolialing the material toward a single layer graphene.

[0243] Each of the functionalized carbons (3DG) materials have different characteristics: Si96 is doped with silicon, Amine43 has the lowest surface area and highest percentage of carbon, GBH has higher incidence of defects and large surface area. The effect of each carbon material loaded in the epoxy adhesive composite material may correlate to differences in the physical properties of the materials. Table 23: Effect of ball milling on carbon materialMaterial ID / IG Elemental % BET surface Layer count (IGA) area from XRD m2 / gCYC Drum 0.39 99+% C 72 17.3 18, blend of3DG carbons(initial)Ball milling 0.99 90.9% C 501 11.7 for 12 hrs, 1.1% N30710’ on / off 3.8% O-105- LYT IP 134.P_LYTEP322WOBall milling 1.25 87.4% C 500 6.9 for 24 hrs, 1.7% N30710 / on / off 7.4% OACS single 1.98 -90% C 500+ 4 to 5 layer graphene 10% O(reference)

[0244] FIG. 15 illustrates a method of ball milling of graphene. The process of ball milling the graphene changes the elements of the graphene material through incorporation of the atmosphere of the sealed environment during the ball milling. As illustrated in FIG. 8, in one approach, graphene is added to a sealed environment with zirconium balls in the presence of air atmosphere (N2, O2, and CO2). The grinding of the graphene breaks the bonds of the graphene and the milled graphene pieces react with the atmosphere of the environment to form pieces of graphene with edge functionality (bound with oxygen). The humidity in the air causes the pieces of graphene edged with oxygen to college hydrogen from the humid environment thereby resulting in the ball milled graphene (GBH) having edge functionality.

[0245] Ball milling of graphene causes a defect that is at the interface of a graphene molecule, the interface being at the edge of one graphene molecule. The defective interface at the edge of graphene is adjacent to the polymer (e.g., epoxy) matrix. In other approaches, functionalization of graphene involves affecting the interior sites of the graphene molecule which causes these functionalized sites to be possibly buried in other layers of graphene. Ball milling results in a higher incidence of edge functionalization (e.g., edge defects) because the interface has higher energy and thus susceptible to lunclionalizalion.

[0246] Table 23 lists the effects of changing the parameters of the ball milling process (12 hrs versus 24 hrs. Increasing the duration of ball milling from 12 hour to 24 hours increases the defects in the graphene sample (0.99 ID / IG to 1.25 ID / IG) and nearly doubles the amount of oxygen in the sample. ACS as a reduced graphene oxide is included to represent a single layer graphene to compare properties, however, the material is expensive. Single layer graphene having a high surface area is well-known to be very hydrophobic and difficult to disperse in an adhesive. Single layer graphene-106- LYT IP 134.P_LYTEP322WOtends to agglomerate very quickly and does not disperse uniformly throughout the adhesive thereby not providing reinforcement in the adhesive. In sharp contrast, ball milled graphene (GBM) disperses easily and uniformly in an epoxy adhesive composite material.

[0247] ONE-PART EPOXY ADHESIVE INCLUDING FUNCTIONALIZED CARBON

[0248] In one aspect, a functionalized graphene may be added to an epoxy adhesive system configured to be a one -part epoxy adhesive system to impart enhanced thermal properties of the epoxy adhesive product. A one-part epoxy adhesive is described as an adhesive system having the epoxy and curing agent together in one mixture and may be acli vated with heat. A one-part epoxy adhesive has a desirable advantage of being uncomplicated (e.g., no need to weight amounts, simple steps, etc.). The process for use of a one-part adhesive includes applying the one-part adhesive to a surface, bonding the adhesive surface with a part to be adhered, and heating the bonded surface and part to cure.

[0249] In one approach, an epoxy adhesive system includes all the components necessary for curing the adhesive product, and may be acli vated by temperature, UV, or moisture. A one-part epoxy adhesive resin is convenient to use because there is no mixing of separate parts at precise ratios and the adhesive will likely behave the same way every time under consistent curing conditions.

[0250] According to one approach, a Ik Epoxy Adhesive is formulated with adhesive components: epoxy resin, toughener, catalyst, and cure accelerator as listed in Table 24. In one approach, a difunctional epoxy resin may be present in the adhesive in an amount of 50 to 90 wt% of total adhesive. In a preferred approach, a difunctional epoxy resin may be present in the adhesive in an amount of 60 to 70 wt% of total adhesive.Table 24. Formulation of Ik Epoxy Adhesive (one-part adhesive).Material Composition Examples-107- LYT IP 134.P_LYTEP322WODifunctional epoxy 50 - 90 wt% diglycidyl ether of bisphenol A resin (BADGE), of bisphenol F, of bisphenol A / FEpoxy toughener 10 - 50 wt% Talc, amorphous silica, core-shell rubber particles, amine-terminated butadiene-acrylonitrile (ATBN), carboxy-terminated butadieneacrylonitrile (CTBN) or epoxy adduct thereof, modified acrylic polymersCatalyst 2 - 10 wt% 2-ethyl-4-methylimidazole,dicyandiamide, benzyldimethylamineCure accelerator 1 - 5 wt% Substituted ureas such as p- chlorophenyl-N, N-dimethylurea, or 3,4-dichlorophenyl-N, N- dimethylurea, or 4,4 methylenebis(phenyldimethyl)urea Thixotropic Additive 1 - 7 wt% Hydrophobically-modified silica

[0251] In one approach an epoxy toughener may be present in the adhesive in an amount of 10 to 50 wt% of total adhesive. In a preferred approach, the epoxy toughener may be present in the epoxy adhesive in an amount of 15 to 25 wt% of the total adhesive. In one approach, the epoxy toughener may include CTBN (carboxyl-terminated nitrile butadiene) that has a carboxyl group and is a different type of hardener compared to the hardeners used in a two-part epoxy adhesive composite material. The epoxy toughener may function as an epoxy adduct.

[0252] In one approach, a catalyst may be present in the adhesive in an amount of 2 to 10 wt% of the total adhesive. In a preferred approach, the catalyst may be present in the adhesive in an amount of 5 to 7 wt% of total adhesive. In one approach, the catalyst may include a dicyandiamide catalyst. In one approach, a cure accelerator may be present in the rein in an amount of 1 to 5 wt% of total adhesive. In a preferred-108- LYT IP 134.P_LYTEP322WOapproach, a cure accelerator may be present in the adhesive in an amount of 2 to 4 wt% of the total adhesive. In one approach, a cure accelerator may include a urea-based cure accelerator.

[0253] In one approach, a thixotropic additive may be present in the adhesive in an amount of 1 to 7 wt% of the total adhesive. In a preferred approach, a thixotropic additive may be present in the adhesive in an amount of 3 to 5 wt% of the total adhesive. In one approach, the thixotropic additive may include silica. In a preferred approach, the thixotropic additive may include hydrophobically-modified silica.

[0254] According to one aspect, a composite material includes an epoxy adhesive and an edge- functionalized graphene. The epoxy adhesive loaded with the edge-functionalized graphene has a Tg that is at least 4 °C higher than a Tg of the epoxy adhesive in the absence of the edge-functionalized graphene. In a preferred approach, the edge-functionalized graphene is an edge-functionalized 3DG. In some approaches, the epoxy adhesive loaded with the edge- functionalized 3DG has enhanced thermal properties while maintaining a mechanical strength of the epoxy adhesive without the edge-functionalized graphene.

[0255] In a preferred approach, a composite material includes a small amount of functionalized 3DG may be added to an epoxy adhesive (e.g., Ik Epoxy Adhesive). In preferred approaches, the graphene is present in an amount that is detectable in the adhesive using metrology techniques. Moreover, graphene is present in an effective amount in the adhesive to cause a perceivable increase in the glass transition temperature of the epoxy adhesive. In one approach, an amount of edge-functionalized graphene (e.g., GBM) added to an epoxy adhesive is in a range of greater than 0.01 wt% to about 1 wt %, 0.01 wt% to about 2 wt%, 0.1 wt% to about 1 wt%, 0.5 wt% to about 2 wt%, 0.5 wt% to about 5 wt%, etc. of the total weight of the epoxy adhesive. In a preferred approach, an amount of edge-functionalized graphene (e.g., GBM) added to an epoxy adhesive is in a range of greater than 0.01 wt% to about 5 wt % of the total weight of the epoxy adhesive. The cdgc-lunclionalizcd 3DG is uniformly dispersed in the epoxy adhesive. In some approaches, the graphene material may be added by planetary mixing, ball milling, shear mixing, any commonly known method for dispersing particulate filler into resinous matrix.-109- LYT IP 134.P_LYTEP322WO

[0256] Table 25A lists the mechanical strength tests of epoxy adhesive composite material loaded with different types of functionalized 3DG. Each composite material of the epoxy adhesive / functionalized 3DG include the formulation of Ik Epoxy Adhesive listed in Table 24. Mechanical strength of composite material was measured in terms of tensile lap shear strength (TLSS) with a neat formulation of the epoxy adhesive (i.e., no 3DG present) and formulations of epoxy adhesive loaded with different types of functionalized 3DG.Table 25A. Properties of Selected Epoxy AdhesivesGraphene TLSS TLSS Shear Elongation Loading PAA Al Cold Rolled modulus at Break psi Steel (Steel) % psi ksiIk Epoxy Adhesive 4,880 + 380 - 3,134 + 92 59.3 6.6 Si96 / 0.1 wt% 4,390 ± 437 - 10% — — — Si96 / 1.0 wt% 4,230 ± 262 - 13% — — —Amine43 / 0.1 wt% 4,740 ± 785 - 3% — — — GBM / 0.5 wt% 5177 + 543 + 6% 3,025 + 123 73.0 4.6Si96 = Si-doped and N-functionalizec 3DGAmine43 = Pyrrole -based 3DGGBM = 3DG that was planetary ball-milled to induce edge functionalization

[0257] Tensile lap shear strength testing of the epoxy adhesives with the different types of functionalized 3DG demonstrated that the presence of any graphene material in the epoxy adhesive does not necessarily result in enhance mechanical properties.As shown in Table 25A (first column TLSS PAA Al where two pieces of aluminum together with the adhesive), graphene loading of a composite material having epoxy adhesive with GBM demonstrated a 6% enhanced lap shear strength relative to neat epoxy adhesive. However, the two other functionalized 3DG, Si96 at two different loadings and Amine43, demonstrated a reduction in lap shear strength relative to neat epoxy adhesive. The increase in lap shear strength of the composite material having epoxy adhesive loaded GBM carbon may be due to the significantly higher surface area of the GBM carbon compared to Si96 carbon and Amine43 carbon (Table 22).-110- LYT IP 134.P_LYTEP322WO

[0258] According to one aspect, a composite material having an epoxy adhesive loaded with edge-functionalized 3DG (e.g., GBM) has a mechanical strength that is at least 5 % higher than a mechanical of the epoxy adhesive in the absence of the edge-functionalized 3DG. In a preferred approach, an epoxy adhesive loaded with edge-functionalized 3DG (e.g., GBM) has a lap shear strength that is at least 5 % higher than a lap shear strength of the epoxy adhesive in the absence of the edge-functionalized 3DG.

[0259] Once it was determined that the presence of the functionalized 3DG in the epoxy adhesive resulted in a reduced lap shear strength, no further testing of these functionalized 3DG (Si96 and Amine43) was conducted. These results demonstrated that certain functionalized 3DG do not generate a positive increase in shear strength in the adhesive (e.g., Si96 at two loadings and Amine43). Thus, the presence of select graphenes in an adhesive may not be a beneficial additive to the adhesive properties. Thus, it was surprising that the presence of ball-milled 3DG in the epoxy adhesive led to higher lap shear strength compared to epoxy adhesive without the ball-milled 3DG.

[0260] To further identify the properties of ball-milled 3DG (graphene ball mill, GBM), different strength tests were conducted the epoxy adhesive loaded with ball-milled graphene (GBM): TLSS with cold rolled steel, shear modulus with steel, and elongation at break as listed in Table 25A. Tensile lap shear strength testing of epoxy adhesive loaded with GBM demonstrated a reduced lap shear strength and an increase in shear modulus of the GBM loaded adhesive. It should be noted that the epoxy adhesive demonstrated different efficacy of adhering to different materials (e.g., aluminum versus steel). A load-displacement curve from the TLSS test showed that shear modulus as increased with the GBM loaded adhesive thereby indicating that the adhesive requires more stress to induce the same amount of strain. The GBM-loaded adhesive demonstrated a similar amount of strength as the adhesive without GBM and the GBM-loaded adhesive was not as elastic. The GBM-loaded epoxy adhesive sample may be less clastic than the epoxy adhesive without GBM. The GBM-loaded epoxy adhesive also demonstrated a lower elongation at break compared to the epoxy adhesive without GBM (4.6 vs 6.6) that may confirm the reduced elasticity of the composite material having GBM-loaded adhesive.-111- LYT IP 134.P_LYTEP322WO

[0261] Due to interactions between the graphene and the segments of the polymer resin, chain mobility is restricted, resulting in higher stiffness (as measured by shear modulus). More energy in the form of temperature may likely be needed to free the polymer chains, resulting in a higher glass transition temperature. This means the material yields less strain (e.g., per unit of load) at both room temperature and elevated temperatures. Referring to modulus, stress versus strain curve, for a given stress the strain is less at different temperatures. Additionally, its maximum service temperature is also higher, since the point at which the bonds become rubbery (i.e., glass transition), is also higher. Since graphene is relatively inert and the loading is fairly low, other material properties, such as density, viscosity, cure temperature are unaffected, allowing for precise control over Tg and shear modulus.

[0262] According to one aspect, a composite material having an epoxy adhesive loaded with edge-functionalized 3DG has a higher glass transition temperature (Tg) compared to the epoxy adhesive without an edge-functionalized 3DG. In one approach, an epoxy adhesive loaded with edge-functionalized 3DG has a Tg higher than at least 5 °C compared to the epoxy adhesive without edge-functionalized 3DG. In one example, an epoxy adhesive loaded with ball-milled 3DG (GBM) has a Tg at least 6 °C higher than a Tg of the epoxy adhesive without GBM. compared to an epoxy adhesive without GBM. Table 25B lists the Tg of selected epoxy adhesives. The Tg was measured for each adhesive: a Ik Epoxy Adhesive (80 / 20), and the Ik Epoxy Adhesive loaded with 0.5 wt% GBM. The epoxy adhesive loaded with GBM has a higher Tg (136 °C) than epoxy adhesive without GBM (131 °C). Since the same composition of epoxy adhesive is included for each adhesive, the change elevation of the Tg by 5 °C is solely due to the presence of GBM to the IK Epoxy Adhesive. A Reference Epoxy (3M Scotch-Weld Epoxy Adhesive, Monrovia, CA) that is a commercially available epoxy adhesive was included because the components resemble the IK epoxy adhesive. The Ik Epoxy Adhesive has a higher Tg than the reference adhesive.-112- LYT IP 134.P_LYTEP322WOTable 25B. Glass Transition Temperature of Selected Epoxy AdhesivesFormulation Glass Transition TemperatureReference Epoxy Adhesive 119 °CIk Epoxy Adhesive 131 °CIk Epoxy Adhesive + 0.5 wt% GBM 136 °C

[0263] SILICON- AND / OR NITROGEN- FUNCTIONALIZED CARBON FOR STRUCTURAL EPOXY COMPOSITES

[0264] In one aspect, doping 3DG with silicon may provide additional opportunities for providing structural integrity of epoxide forms. In one approach, adding Si-doped 3DG up to 3 wt.% of structural epoxide resin may enhance mechanical strength of the epoxide. In some approaches, heteroatom-doped-3DG having specific functionalities engage in chemical reactions within polymer resin network. For example, chemical reactions between heteroatom-doped 3DG and polymer matrix may include reactions involving silanol, siloxane, ring-opening epoxides, etc. In some approaches, a heteroatom-doped 3DG may undergo post processing doping for an additional functionality, such as nitrogen, thiol, etc. in order to enhance additional physical characteristics, such as crosslinking, flexibility, stiffness, etc. In one example, post processing doping of si-3DG with nitrogen, amine, and thiol may provide additional functionality such as nucleophilic groups to bond with the epoxy resin and improve crosslinking (and thus strength).

[0265] In some approaches, the morphology of a Si-doped 3DG may be characterized as being core-shell structure, patchy distribution, etc. Patch distribution is defined as distribution of silicon oxides on the surface of the doped 3DG. In one example, a final product of Si-doped 3DG has silicon present in the lathee structure of the 3DG. Characteristics of morphology of the Si-doped 3DG are listed in Table 26 that represent the Si-doped 3DG samples illustrated in the scanning electron micrograph (SEM) images of the FIG. 16. Each sample of doped-Si 3DG was generated using predefined parameters of the fluidized bed reactor that generated a population of predefined Si-3DG particles having a specific morphology and Si-113- LYT IP 134.P_LYTEP322WOcontent. Analysis of the SEM images of FIG. 16 included determination of silicon levels in each sample as listed in Table 26. Part (a) depicts an image of a sample of a Si-doped 3DG Si42 having a nodular morphology, synonymous with a morphology having nodules that are identified as spherical-shaped features, and a flake morphology identified as planar-shaped features having flat sharp characteristics. Part (b) depicts an image of a sample of a Si-doped 3DG Si49 having predominately a flaky morphology and some nodules. Part (c) depicts an image of a sample a Si-doped 3DG Si50 having a predominately nodular morphology without indication of the flat sharp features of flakes. Parts (d) and (e) depict images of Si-doped 3DG Si51 and Si-N-doped 3DG Si52, respectively, having predominately flakey morphology.

[0266] In one approach, adjusting the reactor to receive a higher power may cause the synthesis of Si-doped 3DG to have a predominant flakey morphology. Si51 particles were generated with using the reactor with a higher power. In addilion, using a higher power increases the production rate of Si-doped 3DG particles (Si51) by an order of magnitude higher than the production rate of Si-doped 3DG at the lower power (e.g., Si42, Si49, and Si50).

[0267] Nodular morphology of the Si-doped 3DG samples appeared to correlate with silicon content. The Si-doped 3DG having nodular morphological features had higher content of silicon. For example, analysis of SEM images with Energy-Dispersive X-ray Spectroscopy (EDS) provides measurements of elemental composition data using targeted analysis of sample surfaces (Table 26). Elemental silicon (at%) is present at highest levels on the compound surfaces in Si-doped 3DG samples having predominately nodular morphology, e.g., Si50 (10.9 at% Si) and Si42 (6.34 at% Si). The Si-doped 3DG having predominately flakey morphological features appears to have lower amounts of silicon present on the compound surfaces, e.g., Si51 (2.9 at% Si).

[0268] The correlation of nodular morphology and elevated silicon content is confirmed with X-ray fluorescence (XRF) analysis. The Si-doped 3DG having predominately nodular morphology without flakes has the highest amount of Si (Si50). However, samples that display nodular morphology in addition to flaky morphology (Si42 and Si49) have higher levels of Si compared to Si-doped 3DG samples having predominately flaky morphology (Si51 and Si52).-114- LYT IP 134.P_LYTEP322WO

[0269] Doping 3DG with silicon and nitrogen may not affect the amount of silicon present in the Si-N-doped 3DG. In one example, doping 3DG included adding the nitrogen-rich precursor HMDSN to facilitate decoration of the 3DG with silicon and nitrogen (Si52). The amount of silicon measured in the Si-N-decorated 3DG is comparable to the amount of silicon measured in Si42 (according to XPS results).

[0270] Table 26. Metrology of silicon-doped 3DGAnalysis Si42 Si49 Si50 Si51 Si52*Nodules NodulesSEM image Nodules Flakes Flakes & flakes & flakesSSA (m2 / g) 142 188 148 127 129 XRF Light elements 92.57 93.21 88.69 93.96 -XRF Si 7.4 6.8 11.3 6 6.2 2D / G (area) 0.99 1.06 0 0.98 -D / G (area) 0.62 0.61 1.88 0.61 -D / G (intensity) 0.46 0.47 1.17 0.5 0.52 La (nm) 30.7 31.3 10.1 31.9 29.6 XRD # Layer 14.4 13.2 7.3 15.1 -IGA-0 0.08 0.08 0.11 0.04 0.043 Si (at%) 6.34 - 10.9 3 4.3 SEM-EDSO (at%) 6.17 - 7.6 5.2 3.9 Si % 4.1 5.1 8.2 2.9 4 XPSO % 1.3 2.5 4.2 2.5 2.2*Si52 is a Si-N-doped 3DG-115- LYT IP 134.P_LYTEP322WO

[0271] A quantitative method for characterizing the morphology of 3DG includes characterization by X-ray diffraction (XRD). A flaky morphology has a higher degree of order in crystalline lattice and thus a higher value of XRD #Layer. Si50 having a predominately nodular features has the lowest layer count (7.3) compared to Si42, Si49 and Si51 (14.4, 13.2, and 15.1, respectively). In some approaches, a ratio of flaky features to nodular features in a representative portion of a Si-doped 3DG may be preferably about twice as many flaky features compared to nodular features.

[0272] In some approaches, the geometry of the morphological features of heteroatom-doped 3DG may have a size and / or aspect ratio indicative of the process of generating the heteroatom-doped 3DG. In one example, Si-doped 3DG samples may be generated having different morphological features that have a predefined geometry. As illustrated in FIGS. 17A-17B, graphitic particles and flakes may be analyzed for average length and aspect ratio (L / W). Part (a) of FIG 17A depicts a high magnification TEM image of graphitic particles of a Si-doped 3DG, Si42. The dimensions, e.g., length (L, solid line) and width (W, dashed line) of a plurality of graphitic particles in a field of Si42 may be measured for calculation of an average length and aspect ratio. The length of a graphitic particles correlates to the largest dimension across a particle along the longitudinal axis. The width of a graphitic particle is the dimension measured across the particle in a perpendicular direction relative to the length and positioned midpoint of the measured length. The inset in part (a) lists the average aspect ratio (L / W) of the graphitic particles being 1.5 from 53 measured particles with a standard deviation of 0.43. In one approach, for a Si-doped 3DG generated using predefined parameters in a plasma reactor, the average aspect ratio of graphitic particles may be in a range of about 1.0 to about 2.0.

[0273] Part (b) of FIG. 17A is a plot of a histogram of the length of graphitic particles in a Si-doped 3DG (Si42). The length, measured along the largest dimension in the longitudinal direction, of the graphitic particles was in a range of about 40 nm to 120 nm with the average length of the population of graphitic particles being in a range of 70 to 80 nm.

[0274] FIG. 17B illustrates the measured dimensions of a 3DG particle having a flake morphology. Part (a) depicts a high magnification TEM image of flakes of a Si-doped 3DG, Si42. The dimensions, e.g., length (L, solid line) and width (W, dashed-116- LYT IP 134.P_LYTEP322WOline) of a plurality of flakes in a field of Si42 may be measured for calculation of an average length and aspect ratio. The length of a graphitic particles correlates to the largest dimension across a flake feature along the longitudinal axis. The width of a flake is the dimension measured across the flake in a perpendicular direction relative to the length and positioned midpoint of the measured length. Part (b) lists the average aspect ralio (L / W) of the graphilic particles being 1.5 from 53 measured particles with a standard deviation of 0.43. In one approach, for a Si-doped 3DG generated using predefined parameters in a plasma reactor, the average aspect ratio of graphitic particles may be in a range of about 1.0 to about 2.0. Part (c) lists the average length in the longitudinal direction of 53 measured graphitic particles being 212.6 nm. The length L as illustrated in the image of part (a) is about 210 nm. These measurements represent one example of Si-doped 3DG having the graphitic particles and nodules and are not meant to be limiting in any way.

[0275] The purity and quality of 3DG may be assessed by Raman Spectrophotometry. The fine detail of graphene in the Si-doped 3DG samples may be characterized by Raman spectrophotometry. The quality of a graphene sample may be determined by a ratio of D-band / G-band intensities (D / G intensity). As the structural disorder of a graphene sample increases the D / G intensity ratio increases. In preferred approaches, a heteroatom-doped graphene has a D / G ralio intensity in a range of 0.3 to 1.0. Analysis of the crystalline characlcrislics of the Si-doped 3DG compounds are listed in Table 26. The D / G intensity ratio of Si42 and Si49 is below 0.5 thereby indicating more structural order and crystalline structure characteristic of having more flake-like features (i.e., more ordered crystalline structure). The D / G intensity ralio of Si50, Si51 , and Si52 being above 0.5 may indicate structural disorder in the samples. The samples with flaky morphology have lower ratios, whereas sample Si50 having predominately nodular morphology has a higher D / G intensity ralio. In one example, a Si-doped 3DG having flaky morphology has a D / G intensity ratio between 0.3 and 1.0.

[0276] Referring to the analysis in Table 26, Si-doped 3DG compounds had comparable specific surface area (SSA) ranging from 129 to 188 m2 / g. Specific surface area (SSA) represents the total surface area of the material per unit mass and provides an indication of a property of each compound. XRD indicate a measure of-117- LYT IP 134.P_LYTEP322WOcrystalline structure and phase composition of the samples. The samples having flaky morphology (Si42, Si49, Si51 , and Si52) demonstrated greater crystalline structure than the sample having primarily nodular morphology (Si50). The lateral size (La) or average crystalline size in nanometers provide an estimation of the crystallite size of the features in the structure. The samples having flaky morphology have larger lateral size in a range of 29 to 31 nm, whereas the sample having the predominately nodular morphology has a smaller lateral size of 10 nm, reflective of a spherical shape rather than a planar shape seen with the flaky morphology.

[0277] FIGS. 18A-18D illustrate morphological characteristics of different Si-doped 3DG particles generated from the plasma reactor using different predefined parameters to generate the desired morphologies of the Si-doped 3DG particles. FIG.18A illustrates TEM images of two different Si-doped 3DG formed using different processes in the plasma reactor. Part (a) depicts a portion of a Si-doped 3DG (labeled Si53) having a predefined morphology including flakes, nodules and graphitic particles. Part (b) depicts a portion of a Si-doped 3DG (labeled Si54) having a predefined morphology that includes mostly nodules.

[0278] FIG. 18B depicts scanning transmission electron microscopy (STEM) images of Si-decorated 3DG Si53 (part (a)) and Si54 (part (b)). Table 27 lists metrology data using the images of FIGS. 18A-18C and transmission electron microscopy-electron energy loss spectroscopy (TEM-EELS) analysis.Table 27. Metrology analysis of Si-doped 3DGAnalysis Si53 Si542D:G Intensity 0.58 0D:G Intensity 0.57 1.12La (nm) 26.9 10.8 XRF Si% 6.61 8.16 SSA: Surface Area (mA2 / g) 128 109IGA Oxygen (Average) 0 0.06 XRD Number of layers 11.2 4.4-118- LYT IP 134.P_LYTEP322WOSi (at%) 7.6 6.8SEM-EDSO (at%) 3.5 4.9Si (at%) 5.6 3.4XPSO (at%) 5.6 4.8TGA wt% remaining 12.8 20.5

[0279] Heteroatom-doped 3DG synthesized using predefined parameters may be characterized as having different forms of heteroatom oxide-like compounds (HeteroatomOx). For example, a HeteroatomOx compound is a SiOx compound having a x number of oxygen molecule associated with each silicon atom. In some approaches, a Si-doped 3DG having graphitic particles may include a combination of SiOx particles and SiOx nodules. In other approaches, a Si-doped 3DG having predominately graphitic nodules may include a combination of SiOx nodules and an SiOx shell coating the graphitic particles. FIG. 18C depicts images of Si53 and Si54 that have fluorescent staining of elements using TEM-EELS. Part (a) depicts the morphology of Si53 particles in the background TEM image and the inset images (al) and (a2) illustrate the composition of the Si53 compound having graphitic particles comprised primarily of carbon (darker shade of gray) with SiOx nodules and SiOx particles. Inset image (al) in a lower magnification and illustrates the SiOx nodules within the graphitic particles of Si53. Inset image (a2) at a higher magnification illustrates SiOx particles within the graphitic particles.

[0280] Part (b) of FIG. 18C depicts the morphology of Si54 in the background TEM image showing primarily nodular morphology that is generated in the plasma reactor using different parameters than used for generating Si53. The inset images, representing the same magnification, illustrate the elemental staining of the graphitic nodules (largely carbon) at different regions of the Si54 compound. The inset image (bl) illustrates a shell surrounding the outer edge of the graphitic nodule where the shell is comprised of SiOx. The inset image (b2) illustrates SiOx nodules within the graphitic nodules.

[0281] FIG. 18D illustrates the surface of Si-3DG on TEM image. Part (a) is a high magnification of a sample of Si53 that shows the layers of the graphitic particles-119- LYT IP 134.P_LYTEP322WOwith the SiOx identified from similar EELS element analysis. Part (b) is a high magnification of Si54 that illustrates the nodular morphology with SiOx shell.

[0282] MECHANICAL PROPERTIES OF STRUCTURAL EPOXY RESIN INCLUDING SILICON- AND SILICON / NITROGEN-FUNCTIONALIZED CARBON

[0283] Thermoset epoxy polymers tend to have good mechanical strength without flexibility. It has long been desired to modify structural epoxy resins to have increased ductility and flexibility. Structural epoxy resins are used to fabricate parts. Structural epoxy resins are not adhesives. In conventional studies, materials added to structural epoxy resins to increase the ductility of an epoxy resin tend to increase flexibility of the epoxy resin at the expense of the structural integrity of the epoxy resin. In one aspect described herein, heteroatom-doped 3DG may have a predefined structural morphology that is compatible with thermoset epoxy polymer matrix and may enhance specific physical properties of the structural epoxy composite. In one approach, a selected heteroatom-doped 3DG enhances the flexibility of the structural epoxy composite. In another approach, a selected heteroatom-doped 3DG enhances the strength of the structural epoxy composite. In yet another approach, a selected heteroatom-doped 3DG enhances the flexibility of the structural epoxy composite without diminishing the mechanical strength of the structural epoxy composite.

[0284] In one aspects, a composite material includes a polymer and a heteroatom-doped graphene having a predominant predefined morphology. As described herein the predominant morphology may be defined as the predominant morphological feature present in greater than 80% of the features of a 3DG. As described herein, the parameters for forming a heteroatom-doped 3DG having a predominant morphology are defined according to the preferred morphology of the synthesized heteroatom-doped 3DG. In one approach, the predefined morphology may be a flaky morphology. In another approach, the predefined morphology may be a nodular morphology. In yet another approach, the predefined morphology may be a particle morphology. In some approaches, the predefined morphology is a combination of morphological features.

[0285] In various approaches, the heteroatom is an element selected for a specific enhanced effect in the polymer when associated with 3DG. In one approach, the-120- LYT IP 134.P_LYTEP322WOheteroatom is silicon. In another approach, the heteroatom is nitrogen. In some approaches, the heteroatom is a combination of silicon and nitrogen. As described herein 3DG is doped in situ during synthesis of the graphene particles with precursor for carbon, silicon, nitrogen, etc.

[0286] In various approaches, the selected heteroatom-doped 3DG may be a Si-doped 3DG, where the Si-3DG is generated to augment specific physical properties of the epoxy system. One approach includes adding Si-doped 3DG to a structural epoxy resin to not only enhance the structural integrity of the epoxy composite but also to increase the ductility and / or flexibility of a structural epoxy resin. For example, Si-3DG added to an epoxy resin may enhance the flexibility of the resulting composite by allowing the epoxy matrix having Si-3DG dispersed throughout to deform clast ical I y and return to its original shape. In another example, Si-3DG added to an epoxy resin may enhance the ductility of the resulting composite by allowing the epoxy matrix to deform to a predefined extent before fracture.

[0287] In various approaches, a selected Si-3DG may be characterized as having specific morphological features that correspond to enhancement of physical properties of the epoxy composite having the Si-3DG dispersed throughout the epoxy matrix. In one approach, Si-3DG having a specific morphological feature (e.g., nodule, flakes, etc.) are dispersed throughout the polymer matrix and the presence of the Si-3DG enhances ductility, flexibility, and / or strength of the epoxy composite material. In another approach, the functionalized Si-3DG particles chemically react with the epoxide polymer matrix thereby enhancing ductility, flexibility, and / or strength of the epoxy composite material.

[0288] In one approach, a Si-3DG having predefined nodular morphology may be added to an epoxy system to enhance ductility of the epoxy resin provide enhanced flexibility of the structural epoxy resin. In one approach, the nodules in a Si-3DG having a nodular morphology may resemble a string of pearls that absorbs energy within the epoxy composite in response to an applied force thereby allowing the epoxy composite to have flexibility and, possibly, enhanced ductility. In some approach, the morphological features of a selected Si-3DG may have plurality of nodules, flakes, graphitic particles, etc. In one approach, a predefined Si-3DG particle may include a series of nodular features (e.g., a string of pearls). In another approach,-121- LYT IP 134.P_LYTEP322WOa predefined Si-3DG particle may include a combination of nodular and flake features. In yet another approach, a predefined Si-3DG particle may include a series of flake features. These approaches are represented as an example of a few options and are not meant to be limiting in any way.

[0289] In another approach, a Si-3DG having predefined flakey morphology may be added to an epoxy system to enhance mechanical strength of the epoxy resin. In yet another approach, a Si-3DG having a combination of nodular morphology and flakes may be added to an epoxy system to enhance flexibility, ductility, and mechanical strength of the epoxy resin.

[0290] In one approach, a composite material having polymer and doped 3DG has a mechanical strength that is at least 10% higher than a mechanical strength of the polymer in the absence of doped 3DG. The doped 3DG may be a heteroatom-doped 3DG where the heteroatom is silicon, nitrogen, etc. The mechanical strength may be the bending strength of the composite as measured in terms of flexural modulus. For example, an epoxy composite having a Si-doped 3DG dispersed throughout the composite may have a bending strength that is at least 10% higher than a bending strength of the epoxy composite without the Si-doped 3DG.

[0291] In another aspect of the aspect, the chemical functionality of 3DG may be tuned to enhance the chemical interaction of heteroatom-doped 3DG with the epoxy resin. For example, an amine group tethered off of 3DG surface forms a covalent bond with epoxy resin via ring opening reaction. This leads to the incorporation of 3DG in epoxy network. In one approach, a functional group, such as a silanol group, amino group, etc. is decorated on the 3DG particle and in turn the functionalized 3DG is then able to participate in a chemical reaction with the epoxy polymer thereby resulting in increased crosslinking, flexibility, ductility, stiffness, etc.

[0292] According to various aspects, heteroatom-doped 3DG may be added to one of the parts of the 2-part epoxy resin to augment the mechanical physical properties of the epoxy resin. In one approach, part A of a 2-part epoxy system is a mixture of epoxies with a thixotropic agent and part B includes amines and / or hardeners. Upon mixing of Part A and B, a hardening occurs with epoxy crosslinking with amine thereby resulting in a hardening of the epoxy resin hardens over time. Addition of Si--122- LYT IP 134.P_LYTEP322WO3DG may accelerate the hardening process. In one example, a commercial structural epoxy resin (SikaBiresin Epoxy Resin (CR110 FR), Madison Heights, MI) includes a part A to part B having a mix ratio of 100:26 by weight. In one example, 3DG samples were compared for their effect on epoxy composite strength by adding different 3DG samples to a commercial part A (using planetary mixing) and adding in part B (hardener). Further processing included degassing that included 3 cycles of vacuum and vent, and curing was carried out at 77 °C for 3 hours, followed by slow cooling. The cured samples (e.g., coupons) were sanded to achieve an even top and bottom surface.

[0293] According to various approaches, the mechanical properties of the structural epoxy resin are enhanced by the presence of Si-3DG / Si-N-3DG in the structural epoxy resin. Mechanical strength of epoxy resin material may be assessed by measuring the flexural modulus, e.g., bending modulus, of the material. Flexural modulus is a material property that describes the material’s stiffness and resistance to bending, measured as the ratio of stress to strain in flexural deformation. Flexural modulus quantifies the composite material’s resistance to bending when a force is applied perpendicular to the long edge of the material.

[0294] In one example, different types of 3DG may affect the flexural modulus of a structural epoxide resin. As a comparison of 3DG, formulations of added 3DG may include ozone-activated 3DG (e.g., ozone-oxidized 3DG, O3-3DG, 3DGO), silicon-doped 3DG (Si-3DG), and in some examples Si-doped 3DG functionalized with amine using APTES or functionalized with thiol using MTPES to affect the mechanical properties of the resulting epoxy resin. One sample of Si-3DG was doped with silicon and nitrogen (N) (Si52). A control additive included in the epoxy resin may include milled glass fiber (MGF) that may be included in epoxy resins to demonstrate addili ve-i nduced enhancement of mechanical strength of a product.

[0295] Without wishing to be bound by any theory, it is believed the correlation of specific morphological and compositional features (e.g., flaky, nodules, etc.) of the Si-decorated 3DG to observed improvements in tensile strength of the epoxy resin may be attributed to specific morphological features of the Si-doped 3DG (Si-3DG). The structural characteristics of Si-3DG enable enhanced interfacial bonding and load transfer in the composite material.-123- LYT IP 134.P_LYTEP322WO

[0296] Table 28 shows different types of 3DG used at various loadings in epoxy resin and the effects on the respective flexural modulus with % improvement compared to the neat epoxy resin prepared on the same day. The plot depicted in FIG.19 illustrates the weighted average of each epoxy resin tested with different loading as listed in Table 28. In particular, Si-3DG having nodular morphology (Si42, part (a) and Si50, part (c) of FIG. 3) showed notable improvement in flexural modulus compared to other types of 3DG. Moreover, Si-3DG demonstrated greater improvement in flexural modulus compared to the average of neat epoxy resin recorded over many different runs.Table 28. Description of 3DG, flexural modulus, and % improvement compared to neat epoxy resin.Sample* Description of Doping Morph* Flexural % Modulus (psi) Improve** Neat epoxy No additives 578,356 ± 31,345 -1% O3-3DG 1 wt% 3DGO 503,911 ± 34,372 -5.8 % 5% O3-3DG 5 wt% 3DGO 552,093 ± 27,075 +3.2 %3% Si42 3 wt% Si-3DG nodular 662,001 ± 24,213 +13.7 %3% Si49 3 wt% Si-3DG flaky 629,920 ± 13,978 +12.5 %3% Si50 3 wt% Si-3DG nodular 657,676 ± 26,122 +3.4 %3% Si51 3 wt% Si-3DG flaky 571,928 ± 28,592 +1.0 % 3% Si52 3 wt% Si- and N-3DG flaky 567,770 ± 5,279 -2.5 % 1% Si50- 1 wt% Si50 post-treated 563,883 ± 23,830 -2.5 % APTES with APTES for aminefunctionality3% Si50- 3 wt% Si50 post-treated 629,808 ± 24,421 +4.4 % APTES with APTES for aminefunctionality-124- LYT IP 134.P_LYTEP322WO3% Si50- 3 wt% Si50 post-treated 603,087 ± 14,412 -4.2 % MPTES with MPTES for thiolfunctionality10% MGF 10 wt% milled glass fiber 576,366 ± 21,746 -0.3 % * All sample formulations were prepared the same way and cured under the same condition at 77 °C for 3 hours, followed by slow cooling.*Morphology of 3DG**% improvement was calculated based on the neat epoxy resin that was prepared and tested on the same day as the epoxy with additives.** Neat epoxy flexural modulus values are combined average of data collected on different days.

[0297] Si-doped 3DG incorporated in structural epoxy resin results in significant improvement, greater than 10%, in flexural modulus that reflects the enhanced mechanical strength of the Si-3DG structural epoxy composite material. Moreover, samples having Si-3DG having a physical characteristic of mixed morphology features (i.e., nodules and flakes) may account for the greatest increase in the flexural modulus of the Si-3DG epoxy resin by 12 to 14%. Furthermore, including Si-3DG in a structural epoxy resin may reduce the weight of the total structural epoxy resin needed to achieve a same degree of mechanical strength.

[0298] The presence of silicon and nitrogen in the Si-N-3DG may provide silicon and nitrogen functionalities that improve compalibi lily and reactivity with the epoxy matrix leading to enhanced performance.

[0299] The mixed morphology Si-3DG shows promising results in structural epoxy resin system that includes enhanced mechanical properties via the patchy silicon oxides having covalent bonding with the epoxy. Often, the inclusion of an additive - in this case Si-3DG - may lead to weakened interfaces between the additive and the polymer network. However, due to the available silica, more specifically silanol (Si-OH) functionalities on the surface of Si-3DG particles, the Si-3DG become an integral with the epoxy network via silane condensation with the epoxy ring.

[0300] It should be understood that the arrangement of components illustrated in the Figures described are exemplary and that other arrangements are possible. It-125- LYT IP 134.P_LYTEP322WOshould also be understood that the various system components (and means) defined by the claims, described below, and illustrated in the various block diagrams represent logical components in some systems configured according to the subject matter disclosed herein.

[0301] For example, one or more of these system components (and means) may be realized, in whole or in part, by at least some of the components illustrated in the arrangements illustrated in the described Figures. In addition, while at least one of these components are implemented at least partially as an electronic hardware component, and therefore constitutes a machine, the other components may be implemented in software that when included in an execution environment constitutes a machine, hardware, or a combination of software and hardware.

[0302] More particularly, at least one component defined by the claims is implemented at least partially as an electronic hardware component, such as an instruction execution machine (e.g., a processor-based or processor-containing machine) and / or as specialized circuits or circuitry (e.g., discreet logic gates interconnected to perform a specialized function). Other components may be implemented in software, hardware, or a combination of software and hardware. Moreover, some or all of these other components may be combined, some may be omitted altogether, and additional components may be added while still achieving the functionality described herein. Thus, the subject matter described herein may be embodied in many different variations, and all such variations are contemplated to be within the scope of what is claimed.

[0303] In the description above, the subject matter is described with reference to acts and symbolic representations of operations that are performed by one or more devices, unless indicated otherwise. As such, it will be understood that such acts and operations, which are at times referred to as being computer-executed, include the manipulation by the processor of data in a structured form. This manipulation transforms the data or maintains it at locations in the memory system of the computer, which reconfigures or otherwise alters the operation of the device in a manner well understood by those skilled in the art. The data is maintained at physical locations of the memory as data structures that have particular properties defined by the format of the data. However, while the subject matter is being described in the foregoing-126- LYT IP 134.P_LYTEP322WOcontext, it is not meant to be limiting as those of skill in the art will appreciate that various of the acts and operations described hereinafter may also be implemented in hardware.

[0304] To facilitate an understanding of the subject matter described herein, many aspects are described in terms of sequences of actions. The description herein of any sequence of actions is not intended to imply that the specific order described for performing that sequence must be followed. All methods described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

[0305] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the subject matter (particularly in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation, as the scope of protection sought is defined by the claims as set forth hereinafter together with any equivalents thereof emit led to. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illustrate the subject matter and does not pose a limitation on the scope of the subject matter unless otherwise claimed. The use of the term “based on” and other like phrases indicating a condition for bringing about a result, both in the claims and in the written description, is not intended to foreclose any other conditions that bring about that result. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention as claimed.

[0306] As also used herein, the term “about” denotes an interval of accuracy that ensures the technical effect of the feature in question. In various approaches, the term “about” when combined with a value, refers to plus and minus 10% of the reference value. For example, a thickness of about 10 nm refers to a thickness of 10 nm ± 1 nm, a temperature of about 50 °C refers to a temperature of 50 °C ± 5 °C, etc.-127- LYT IP 134.P_LYTEP322WO

[0307] Unless expressly defined otherwise herein, each component listed in a particular approach may be present in an effective amount. An effective amount of a component means that enough of the component is present to result in a discernable change in a target characteristic of the ink, printed structure, and / or final product in which the component is present, and preferably results in a change of the characteristic to within a desired range. One skilled in the art, now armed with the teachings herein, would be able to readily determine an effective amount of a particular component without having to resort to undue experimentation.

[0308] The aspects described herein included the one or more modes known to the inventor for carrying out the claimed subject matter. Of course, variations of those aspects will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventor intends for the claimed subject matter to be practiced otherwise than as specifically described herein. Accordingly, this claimed subject matter includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

-128- LYT IP 134.P_LYTEP322WOCLAIMSWhat is claimed is:

1. A composite material comprising:a polymer; anda graphene-containing material having nodular and / or flaky morphologies, wherein the composite material has a glass transition temperature that is at least three degrees Celsius higher than a glass transition temperature of the polymer in absence of the graphene-containing material.

2. The composite material of claim 1, wherein the graphene-containing material is three-dimensional graphene.

3. The composite material of claim 1, wherein the graphene-containing material is essentially free of oxygen-containing species.

4. The composite material of claim 1 , wherein the graphene-containing material is essentially pure carbon.

5. The composite material of claim 1, wherein the graphene-containing material is dispersed uniformly in the polymer.

6. The composite material of claim 1, wherein the nodular morphologies are configured to inhibit crack initiation and propagation of the composite material during impaction.

7. The composite material of claim 1, wherein the composite material has an exotherm enthalpy at least 10% lower than an exotherm enthalpy of the polymer in absence of the graphene-containing material during curing.

8. The composite material of claim 1, wherein the polymer is an epoxy resin.-129- LYT IP 134.P_LYTEP322WO9. The composite material of claim 1, wherein the composite material has a mechanical strength at least 4% higher than a mechanical strength of the polymer in absence of the graphene-containing material at an elevated temperature of at least 90 degrees Celsius.

10. The composite material of claim 1, wherein the composite material has a tensile lap shear strength at least 5% higher than the polymer in absence of the graphene-containing material.

11. A composite material, comprising:a polymer; anda three-dimensional graphene,wherein the composite material has a mechanical strength above 5 mega Pascals (MPa) at a temperature above 90 degrees Celsius.

12. The composite material of claim 11, wherein the three-dimensional graphene is an unfunctionalized three-dimensional graphene.

13. The composite material of claim 11, wherein the mechanical strength is tensile lap shear strength.

14. The composite material of claim 11, wherein the polymer is an epoxy resin.

15. The composite material of claim 11, wherein the composite material is an adhesive that is configured to bond a first material to a second material, wherein the first and second material have different compositions.

16. The composite material of claim 15, wherein a composition of the first material is a polymer material and a composition of the second material is a metal.

17. The composite material of claim 11, wherein the composite material is an adhesive that is configured to adhere to an adherend, where a glass-transition-130- LYT IP 134.P_LYTEP322WOtemperature of the adhesive is higher than a glass transition temperature of the adherend.

18. The composite material of claim 17, wherein the adherend is chosen from a polymer material and a carbon fiber reinforced polymer.

19. The composite material of claim 18, wherein the polymer material includes nylon.

20. The composite material of claim 11 , wherein the polymer is formed from a composition that includes an epoxy resin having greater than three epoxy groups.

21. The composite material of claim 20, wherein the composition includes a thermoplastic toughener.

22. A composite material, comprising:an epoxy adhesive; andan amine-functionalized graphene, wherein the epoxy adhesive has a mechanical strength that is at least 5 % higher than a mechanical strength of the epoxy adhesive in the absence of the amine- functionalized graphene.

23. The composite material of claim 22, wherein amine-functionalized graphene is an amine-functionalized three-dimensional graphene.

24. The composite material of claim 22, wherein the mechanical strength is tensile lap shear strength.

25. The composite material of claim 22, wherein the amine-functionalized graphene includes silicon.-131- LYT IP 134.P_LYTEP322WO26. The composite material of claim 25, wherein the amine-functionalized graphene includes oxygen, the oxygen being substantially associated with silicon as a silicon oxide compound.

27. The composite material of claim 26, wherein the silicon oxide compound is localized on an outer edge of carbon nodules defining the amine- functionalized graphene.

28. The composite material of claim 22, wherein the amine-functionalized graphene has a surface area in a range of about 100 to 200 meter squared per gram (m2 / g).

29. The composite material of claim 22, wherein the amine-functionalized graphene has a D / G ratio of Raman band intensities between 0.3 and 1.0.

30. The composite material of claim 22, wherein the amine-functionalized graphene has a predominant predefined morphology.

31. The composite material of claim 30, wherein the predominant predefined morphology is a combination of flakes and nodules.

32. The composite material of claim 22, wherein the epoxy adhesive is configured to be formed from a 2-part epoxy adhesive system.

33. The composite material of claim 22, wherein the amine-functionalized graphene is uniformly dispersed in the epoxy adhesive.

34. A composite material, comprising:an epoxy adhesive; andan edge-functionalized three-dimensional graphene, wherein the epoxy adhesive has a glass transition temperature that is at least 4 °C higher than a glass transition temperature of the epoxy adhesive in the absence of the edge-functionalized three-dimensional graphene.-132- LYT IP 134.P_LYTEP322WO35. The composite material of claim 34, wherein the edge-functionalized three- dimensional graphene has a physical characteristic of being formed using ballmilling.

36. The composite material of claim 34, wherein the epoxy adhesive is configured to be formed from a one-part epoxy adhesive system.

37. The composite material of claim 34, wherein the edge-functionalized three- dimensional graphene has a surface area in a range of greater than about 300 meters to about 600 meters squared per gram (m2 / g).

38. The composite material of claim 34, wherein the edge-functionalized three- dimensional graphene has a D / G ratio of Raman band intensities in a range of about 0.50 to less than 2.00.

39. The composite material of claim 34, wherein the epoxy adhesive has a mechanical strength that is at least 5 % higher than a mechanical strength of the epoxy adhesive in the absence of the edge-functionalized three- dimensional graphene.

40. The composite material of claim 39, wherein the mechanical strength is tensile lap shear strength.

41. The composite material of claim 34, wherein an amount of the edge- functionalized three-dimensional graphene is in a range of greater than 0.01 weight% to about 1.0 weight% of a total weight of the composite material.

42. A composite material, comprising:a polymer; anda heteroatom-doped graphene having a predominant predefined morphology, wherein the composite material has a mechanical strength that is at least 10% higher than a mechanical strength of the polymer in absence of the heteroatom-doped graphene.-133- LYT IP 134.P_LYTEP322WO43. The composite material of claim 42, wherein the predefined morphology is a flaky morphology.

44. The composite material of claim 42, where in predefined morphology is a nodular morphology.

45. The composite material of claim 44 wherein the doped heteroatom is configured to form a shell on graphene nodules.

46. The composite material of claim 42, wherein the predefined morphology is a particle.

47. The composite material of claim 42, wherein the predefined morphology is a combination of nodular and flaky morphologies.

48. The composite material of claim 42, wherein the heteroatom is silicon.

49. The composite material of claim 42, wherein the heteroatom includes silicon and nitrogen.

50. The composite material of claim 42, wherein the heteroatom-doped graphene includes oxygen, the oxygen being substantially associated with silicon as a silicon oxide compound.

51. The composite material of claim 42, wherein the heteroatom-doped graphene is a heteroatom-doped three-dimensional (3D) graphene.

52. The composite material of claim 42, wherein the polymer is an epoxy resin.

53. The composite material of claim 42, wherein the mechanical strength is flexural modulus.-134- LYT1P134.P_LYTEP322WO54. The composite material of claim 42, wherein the heteroatom-doped graphene having flaky morphology has a D / G ratio of Raman band intensities between 0.3 and 1.0.

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