Polymer matrix composites and methods for making same

Abstract

Carbon composites containing carbon fibers are disclosed that exhibit unique and advantageous mechanical properties, including interlaminar shear strength, compressive strength, and resistance to forces applied at angles that deviate from parallel to the longitudinal axis of the overall fiber. These improvements allow for the use of less material while delivering improved strength in a myriad of practical applications, reducing the overall financial costs of manufacturing, distributing, and commercializing the resulting products. These advantages are optimized by utilizing the inventive manufacturing techniques that incorporate carbon filaments into carbon fibers, preferably carbon filaments that include three-dimensional (3D) graphene platelets into said fibers. The filaments mechanically reinforce both the individual fibers and the composition that includes multiple fibers that are strung together by a single cord by "bridging" the individual fibers with 3D graphene ligands. The combined results of these inventive efforts include materials that exhibit superior mechanical strength and reduced mass compared to conventional carbon fibers.

Description

[Technical field]

[0001] Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 318,213, entitled "Graphene Reinforced Carbon Fibers," filed March 9, 2022, and U.S. Utility Patent Application No. 18 / 115,643, entitled "POLYMER MATRIX COMPOSITES, AND METHODS OF MAKING THE SAME," filed February 28, 2023, the contents of which are incorporated by reference in their entireties herein.

[0002] The inventive concepts described herein relate to carbon composites, and in particular graphene-reinforced carbon fiber compositions, that have unique and advantageous mechanical properties. [Background technology]

[0003] Continuing efforts in the field of materials synthesis call for continuous improvements in the quality and efficiency of producing various compositions of matter for a myriad of industrial, commercial, locomotive, and other applications. Of particular interest is the ability to produce stronger and lighter materials while simultaneously reducing production costs, both from a financial standpoint and in terms of reducing the amount of raw material required to produce the final product.

[0004] One promising candidate is carbon fiber. Carbon fiber is an engineered strain with hundreds or thousands of parallel filaments. Made of anisotropic carbon, carbon fibers are typically produced by a series of controlled heat treatments of precursor polymer fibers. Multiple carbon fibers can be twisted into yards, woven into fabrics, or mixed with other materials to produce carbon fiber composites. Carbon fiber has high tensile strength, low density, high modulus, and excellent creep and chemical resistance, making carbon fiber composites have a high strength-to-weight ratio suitable for a wide range of applications in aerospace, military, high-end electric vehicles, machine parts, and civil engineering, among others. Summary of the Invention [Problem to be solved by the invention]

[0005] However, a simple transition from the use of traditional polymers to the use of carbon fibers is insufficient to address the challenges presented in the context of modern materials manufacturing. For example, carbon fibers are known to suffer from low compressive strength, low interlaminar shear strength, and tend to fall apart under relatively low forces applied at angles that deviate from substantially parallel to the common longitudinal axis of the fibers, e.g., via tension applied at an angle perpendicular to the longitudinal axis of the fibers.

[0006] Thus, there is a need to improve the mechanical strength of carbon fibers, as well as address other problems associated with the prior art. [Means for solving the problem]

[0007] Polymer matrix composite compositions of matter and methods for their manufacture are disclosed. The compositions of matter generally include carbon fibers with carbon fiber filaments (which may include three-dimensional (3D) graphene) located within the bulk, on the outer surface(s), and / or structurally bonded to the carbon fibers. In the latter case, the carbon fiber filaments may be present in an optional polymer matrix that is at least partially in contact with the surface(s) and / or internal voids of the carbon fibers. In all cases, the inclusion of carbon fiber filaments improves the mechanical strength of the resulting material according to several important metrics, including but not limited to compressive strength and interlaminar shear strength. In addition, particularly in embodiments that include 3D graphene, additional functionalization, surface modification, and property tuning of the composite material is permitted. Various aspects and advantages of utilizing the inventive concepts described herein will become apparent upon a complete review of the specification and drawings. The exemplary aspects presented immediately below are intended to be illustrative and should not be considered as limiting the scope of the invention.

[0008] According to one embodiment, a composition of matter includes a carbon fiber having a plurality of carbon fiber filaments disposed within and / or disposed on a surface of the carbon fiber, at least some of the plurality of carbon fiber filaments each independently characterized by a longitudinal axis oriented at an angle that deviates substantially from parallel to a longitudinal axis of the carbon fiber.

[0009] According to another aspect, a composition of matter includes carbon fibers having a plurality of graphene platelets disposed within and / or disposed (e.g., sized) on a surface(s) of the carbon fibers, at least some of the graphene platelets comprise 3D graphene.

[0010] Optionally, the 3D graphene may be part of one or more carbon filaments disposed within or on the carbon fiber. Furthermore, at least some of the carbon atoms in the 3D graphene may be sp 3 The 3D graphene may be characterized by orbital hybridization. Preferably, the 3D graphene comprises a plurality of ligands incorporated into the bulk of the carbon fiber, the outer surface of the carbon fiber, or both the bulk and the outer surface of the carbon fiber. For example, the carbon filaments and / or graphene platelets may be sized on the surface(s) of the carbon fiber. With continued reference to the graphene platelets, in some aspects, the plurality of graphene platelets may each independently comprise single layer graphene (SLG), few layer graphene (FLG), multilayer graphene (MLG), or any combination thereof. In further embodiments, at least some of the graphene platelets may comprise one or more polycyclic aromatic hydrocarbons (PAHs) adsorbed to one or more adsorption sites on one or more surfaces of the graphene platelets.

[0011] In some aspects, the longitudinal axes of at least some of the plurality of carbon fiber filaments are characterized by a substantially random distribution of orientation angles that each independently deviate from parallel to the longitudinal axis of the carbon fiber. Moreover, the longitudinal axes of other of the plurality of carbon fiber filaments can be aligned substantially parallel to the longitudinal axis of the carbon fiber. When the composition includes graphene platelets, the orientation planes of at least some of the graphene platelets can each independently be oriented at an angle that substantially deviates from parallel to the longitudinal axis of the carbon fiber.

[0012] In more embodiments, the carbon fiber filaments include either discontinuous filaments, continuous filaments, or both.

[0013] Preferably, some or all of the carbon fiber filaments are characterized by an aspect ratio in the range of about 100:1 to about 1000:1.

[0014] Advantageously, according to selected embodiments, the composition substantially excludes oxygen, which may refer to the exclusion of molecular oxygen (e.g., the gas present in the void spaces within carbon fibers) or atomic oxygen in the chemical composition of the various components of the composition of matter of the present invention.

[0015] Of course, certain embodiments may include multiple carbon fibers, in which the multiple carbon fibers are preferably aligned substantially parallel along their longitudinal axes, with at least some of the carbon fiber filaments bridging the multiple carbon fibers, and / or at least some of the ligands of the 3D graphene bridging the multiple carbon fibers, providing additional mechanical strength to the composition of matter.

[0016] Thus, according to various aspects, the inventive concepts of the present disclosure should be understood to include embodiments in which the carbon fiber filaments and / or graphene platelets (one or both of which may include three-dimensional graphene and any associated properties thereof, as described herein) are present within the bulk volume of the carbon fiber(s), sized to the outer surface(s) of the carbon fiber(s), present within a binder matrix, structurally bonded to the carbon fiber(s), or any permutation or combination of these structural arrangements. Furthermore, whether the composition of matter includes one or more carbon fibers, the composition of matter may optionally include a polymer matrix or other suitable binder matrix that may itself have carbon fiber filaments and / or graphene platelets disposed therein. Furthermore, these filaments and / or platelets may be structurally bonded to some or all of the carbon fibers, providing yet further mechanical strength and other improvements to the composite.

[0017] For example, in one approach, the composition of matter includes carbon fibers having a plurality of carbon fiber filaments sized on one or more outer surfaces, characterized in that the carbon fiber filaments either include graphene platelets, have some or all of the longitudinal axes of the carbon fiber filaments oriented at an angle that deviates substantially from parallel to the longitudinal axis of the carbon fiber, or include graphene platelets and have some or all of the longitudinal axes of the carbon fiber filaments oriented at an angle that deviates substantially from parallel to the longitudinal axis of the carbon fiber. The carbon fibers may additionally or alternatively include (or exclude) any of the foregoing features, limitations, structural arrangements, etc., in any permutation or combination without departing from the scope of the inventive concept of the present disclosure.

[0018] In another exemplary approach, a composition of matter includes carbon fibers and a binder matrix, where the binder matrix is ​​structurally bonded to the carbon fibers via either a plurality of carbon fiber filaments in the binder matrix, a plurality of graphene platelets in the binder matrix, or both a plurality of carbon fiber filaments in the binder matrix and a plurality of graphene platelets in the binder matrix. The carbon fibers may additionally or alternatively include (or exclude) any of the foregoing features, limitations, structural arrangements, etc., in any permutation or combination without departing from the scope of the inventive concepts of the present disclosure.

[0019] Turning now to methods of manufacture, according to one embodiment, a method of producing carbon fiber filaments includes receiving a spinning dope containing a plurality of polymer particles and a plurality of graphene platelets in liquid form, extruding the spinning dope through one or more openings, and solidifying the extruded spinning dope into one or more polymer filaments.

[0020] According to another embodiment, a method of producing carbon fiber filaments includes exposing an extrusion spinning dope to a plurality of graphene platelets. Note that this method can be performed simultaneously with or after solidifying the extrusion spinning dope into one or more polymer filaments, in selected approaches.

[0021] According to yet another aspect, a method of producing carbon fiber filaments includes oxidizing one or more polymer filaments at a first temperature, carbonizing the one or more polymer filaments at a second temperature, and graphitizing the one or more polymer filaments at a third temperature. In various embodiments, the method may be performed independently or after solidifying an extrusion spinning dope into one or more polymer filaments.

[0022] According to yet another aspect, a method of producing a carbon fiber filament includes applying a sizing layer containing a plurality of graphene platelets to a carbon fiber filament.

[0023]

[0013] Again, the foregoing exemplary aspects and implementations are offered by way of illustration and not limitation. Additional features and advantages of the inventive concepts described herein are disclosed in the following detailed description and illustrated in the various drawing figures. [Brief description of the drawings]

[0024] [Figure 1A] 1 shows a simplified schematic diagram of an exemplary carbon fiber composite, according to one embodiment. [Figure 1B] 1B is a scanning electron micrograph (SEM) image of a spun carbon-based fiber as shown in FIG. 1A, according to one embodiment. [Diagram 2] FIG. 1 illustrates a simplified schematic diagram of an exemplary polymer filament, according to some embodiments. [Figure 3A] 1 is an image depicting conventional carbon fiber in its pristine state after manufacture, containing a number of voids. [Figure 3B] 1 is an image depicting conventional carbon fiber after drawing, still containing a number of voids. [Figure 3C] 1 is an image depicting conventional carbon fiber after drawing, still containing a number of voids. [Figure 3D] 1 is an image depicting a conventional carbon fiber in its final state after annealing, still containing a plurality of voids. [Figure 3E] FIG. 2 is a simplified schematic diagram of an exemplary carbon fiber having a plurality of carbon fiber filaments and / or platelets disposed therein, according to some embodiments. [Figure 4] FIG. 3C shows a simplified schematic diagram of an exemplary three-dimensional (3D) graphene platelet that can be used to fabricate the polymer filament of FIG. 2 or the carbon fiber filament of FIG. 3E, according to some embodiments. [Diagram 5]1 is a SEM image of an exemplary polymer formulation including three-dimensional (3D) graphene, according to an embodiment. [Figure 6] FIG. 1 is a conformal microscope image of the interior volume of a carbon fiber having 3D graphene ligands intermeshed together throughout the bulk of the fiber, according to one embodiment. [Figure 7A] 1 is an image showing a plurality of carbon fibers intermeshed with 3D graphene from a cross-sectional view according to an exemplary embodiment. The depicted view shows 3D graphene intermeshed with the entire structure as well as with the individual fibers, filling the interstitial voids between the individual fibers, according to an exemplary embodiment. [Figure 7B] FIG. 7B shows one of the carbon fibers depicted in FIG. 7A illustrating 3D graphene intermeshing with both the bulk and the outer surface of the carbon fiber, according to one embodiment. [Figure 7C] FIG. 2 is a SEM image showing the ligand structure of 3D graphene according to one approach. [Figure 8A] 1 is a micrograph image showing a conventional carbon fiber without carbon fiber filaments or particles disposed therein from a cross-sectional view according to one approach. [Figure 8B] FIG. 2 is a microscopic image showing a carbon fiber of the present invention having a plurality of carbon fiber filaments or particles disposed therein from a cross-sectional view according to another approach. [Figure 9A] FIG. 1 is a graph comparing the compressive strength of PAN-based polymer filaments and PAN / graphene-0.075 composite carbon fibers at various stages of manufacturing, according to one approach. [Figure 9B] 1 is a graph comparing the Young's modulus of PAN-based polymer filaments and PAN / graphene-0.075 composite carbon fibers at various stages of manufacture, according to one approach. [Figure 9C] 1 is a graph comparing the strain of PAN-based polymer filaments to the strain of PAN / graphene-0.075 composite carbon fibers at various stages of manufacture, according to one approach. [Figure 10A]1 shows a flowchart depicting example operations for producing carbon fiber filaments, according to some embodiments. [Figure 10B] 1 shows a flowchart depicting example operations for producing carbon fiber filaments, according to some embodiments. [Figure 10C] 1 shows a flowchart depicting example operations for producing carbon fiber filaments, according to some embodiments. [Figure 11] 1 shows a flowchart depicting another example operation for producing carbon fiber filaments, according to some other embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Like reference numbers and designations in the various drawings indicate like elements.

[0026] Aspects of the present disclosure are provided in the following description and associated drawings directed to various examples provided for illustrative purposes. Alternative aspects may be devised without departing from the scope of the present disclosure. Additionally, well-known elements of the present disclosure will not be described in detail or will be omitted so as not to obscure the relevant details of the present disclosure.

[0027] Carbon fiber (CF) is commonly used as a type of reinforcing material in composites for lightweight composite applications. Although carbon fiber has certain desirable mechanical properties for some high-end applications, CF generally has low compressive strength. Additionally, the use of carbon fiber composites in other fields is limited due to high production costs. Currently commercially available carbon fibers are mainly produced using expensive precursor materials such as polyacrylonitrile (PAN), which accounts for more than 50% of the production cost of PAN-based CF. Moreover, the time- and energy-consuming manufacturing process of PAN-based CF further increases the production cost. Low-cost precursor materials such as pitch, rayon, and other polymers have been utilized to produce CF. However, the mechanical properties of CF derived from these low-cost precursors are insufficient for use in many applications, including as a reinforcing material.

[0028] The subject matter described in the present disclosure may be used to produce carbon fibers from low-cost precursors with the same or better mechanical properties than more expensive PAN-based carbon fibers. The subject matter described in the present disclosure may also be used to reduce the time and energy associated with the production of PAN-based carbon fibers, thereby reducing the production cost of such carbon fibers. Carbon fibers may consist of hundreds or thousands of carbon fiber filaments. Carbon fiber filaments are produced by polymer filaments, which become carbon fiber filaments after oxidation, carbonization, and graphitization. In some embodiments, the polymer filaments may be produced via wet spinning, electrospinning, or melt spinning. In some aspects, multiple graphene platelets may be added to the spinning process of the polymer filaments to minimize internal voids or defects in the microstructure of the polymer filaments.

[0029] Adding graphene platelets to the spinning process may also allow for an increase in graphitic microstructure in the resulting carbon fiber filament. In some other embodiments, multiple graphene platelets may be added to the carbon fiber filament as a coating or sizing to improve adhesion between the carbon fiber filament and the surrounding binder matrix. As used herein, the term "sizing" should be understood to refer to any process of covering or coating, in whole or in part, a fiber or equivalent thread-like structure, where the covering or coating enhances or detriments one or more existing properties or characteristics of the fiber (or fiber equivalent), imparts one or more new properties or characteristics onto the fiber (or fiber equivalent), eliminates one or more existing properties or characteristics of the fiber (or fiber equivalent), or eliminates any combination thereof that would be understood by one of ordinary skill in the art upon reading this disclosure.

[0030] The carbon fiber filaments may be manufactured by the techniques described herein or may be obtained from a commercial manufacturer. In some cases, the graphene platelets may be surface modified to have one side polar and the other side non-polar. For example, polycyclic aromatic hydrocarbons (PAHs) may be adsorbed to one or more adsorption sites on a first side of the graphene platelets, increasing the polarity of the first side of the graphene platelets relative to the second side of the platelets.

[0031] Certain embodiments of the subject matter described in this disclosure may be implemented to realize one or more of the following potential advantages: Existing PAN-based carbon fibers may not be suitable for many cost-sensitive applications, such as electric vehicles, which have high fuel efficiency for the average consumer. In some embodiments, the techniques disclosed herein can be used to produce multiple carbon fiber filaments from low-cost precursors that have the same or better mechanical properties than PAN-based carbon fibers. Such mechanical properties include, but are not limited to, tensile strength, tensile modulus, and compressive strength parallel to the carbon fiber axis, tensile strength, tensile modulus, and compressive strength perpendicular to the carbon fiber axis, in-plane shear strength and modulus, interlaminar shear strength, and flexural strength and modulus. In this way, carbon fibers and carbon fiber composites produced using the techniques described herein may have desirable mechanical properties at a market price that is considered more affordable by the average consumer.

[0032] FIG. 1A illustrates an exemplary carbon fiber composite 100 according to one or more embodiments of the subject matter disclosed therein. The carbon fiber composite 100 is shown to include four carbon fibers 110 parallel to one another and an optional binder matrix 120. The binder matrix 130 may hold or bond the carbon fibers 110 and increase their stiffness. In some embodiments, the carbon fiber composite 100 may contain four or more carbon fibers 110. In some embodiments, one or more carbon fibers 110 may be arranged vertically before they are mixed with the binder matrix 120. In some other embodiments, one or more carbon fibers 110 may be woven into a fabric, arranged in piles, or pre-oriented in any other arrangement before being mixed with the binder matrix 120. The binder matrix 120 may be a resin, or any other suitable material capable of bonding two physical surfaces together. For example, the binder matrix 120 may include thermoset and thermoplastic polymers, metals, ceramic compounds, or any combination thereof. The binder matrix 120 can be a resin matrix such that the carbon fiber composite 100 is a carbon fiber reinforced polymer (CFRP) when one or more carbon fibers 110 are mixed with a resin matrix. In some embodiments, the resin matrix can include an epoxy resin, a polyester resin, a vinyl ester resin, a nylon resin, or any combination thereof.

[0033] In the example of FIG. 1A, each of the carbon fibers 110 includes a plurality of carbon fiber filaments 130. The carbon fiber filaments 130 may include an outer body 132, a cross-sectional surface 134, and a plurality of graphene platelets (not shown in FIG. 1A for simplicity) containing layers of graphene. In some aspects, each of the graphene platelets may include single layer graphene (SLG), few layer graphene (FLG), multi-layer graphene (MLG), or any combination thereof. In some implementations, the cross-sectional surface 134 may have a variety of shapes. For example, the cross-sectional surface 134 may have a regular shape, such as a circle, a rectangle, or a triangle. In other examples, the cross-sectional surface 134 may have an irregular shape, such as a kidney-like shape. In some implementations, the plurality of carbon fiber filaments 130 may be oriented parallel to one another along the length of the carbon fiber 110. In some other implementations, the plurality of carbon fiber filaments 130 may be oriented in different directions relative to one another within the carbon fiber 110.

[0034] For example, as shown and described in more detail below with reference to FIG. 3E, some or all of the carbon fiber filaments 130 may each independently have a longitudinal axis oriented at an angle that deviates from parallel to the longitudinal axis of the respective carbon fiber 110 to which it is disposed. In some approaches, the carbon fiber filaments 330 may be collectively characterized by the fact that their longitudinal axes exhibit a substantially random or normal distribution with respect to the orientation angle of the carbon fiber filaments 130 relative to the orientation of the longitudinal axis of the carbon fiber 110 to which it is disposed. In still more approaches, some of the carbon fiber filaments 130 may be oriented substantially parallel to the longitudinal axis of the carbon fiber 110 to which they are disposed, while others of the carbon fiber filaments 130 may have a longitudinal axis oriented at an angle that deviates from parallel to the longitudinal axis of the respective carbon fiber 110 to which it is disposed.

[0035] In a preferred approach, at least about 5% of the carbon fiber filaments 130 are each independently characterized as having a longitudinal axis oriented at an angle that deviates from parallel to the longitudinal axis of the respective carbon fiber 110 in which the carbon fiber filaments 130 are disposed. For example, according to various embodiments, at least about 5%, at least about 10%, at least about 20%, at least about 25%, at least about 33%, at least about 40%, at least about 50%, at least about 60%, at least about 66%, at least about 75%, at least about 80%, at least about 90%, at least about 95%, at least about 97%, at least about 98%, at least about 99%, about 99% or more, or even 100% of the carbon fiber filaments 130 disposed in the carbon fiber 110 are each independently characterized as having a longitudinal axis oriented at an angle that deviates from parallel to the longitudinal axis of the respective carbon fiber 110. In a preferred approach, the percentage of carbon fiber filaments 130 having an orientation angle that deviates substantially from parallel to the longitudinal axis of the carbon fibers 110 ranges from about 0.01% to about 47%.

[0036] As referred to herein, an orientation angle is considered to "deviate" or "substantially deviate" from parallel to a given reference point or feature (e.g., the axis of a thread-like or elongated structure, preferably the longitudinal axis of the carbon fibers, most preferably the longitudinal axis of the carbon fibers) when the orientation angle deviates from parallel by an amount of at least 30 degrees, at least 45 degrees, at least 60 degrees, at least 75 degrees, or 90 degrees (i.e., perpendicular or orthogonal), according to various embodiments.

[0037] Those skilled in the art will further appreciate that different embodiments of the inventive concepts herein may include substantially uniform reinforcement of the entire volume and / or surface(s) of a fiber, or non-uniform reinforcement thereof. For example, it may be advantageous to selectively reinforce only those portions of a fiber that are known or expected to experience mechanical failure under a given stress. In other embodiments, it may be desirable to omit reinforcing certain portions of a fiber to include intended failure points that are likely to experience mechanical failure under a given stress. These and other equivalent engineering considerations may be implemented in any suitable manner without departing from the scope of the inventive concepts of the present disclosure.

[0038] In some examples, the carbon fiber filament 130 may be a continuous fiber having a length identical to that of the carbon fiber 110. In some other examples, the carbon fiber filament 130 may be discontinuous and have a length shorter than that of the carbon fiber 110 due to one or more breaks 136. For example, in various approaches, the carbon fiber filament 130 may be characterized by an aspect ratio ranging from about 100:1 to about 1000:1. For example, without limitation, the carbon fiber filament may have an aspect ratio of about 100:1, about 150:1, about 250:1, about 400:1, about 500:1, about 666:1, about 750:1, about 800:1, about 900:1, about 950:1, about 975:1, about 990:1, about 999:1, or about 1000:1, according to various embodiments. As will be understood by those skilled in the art upon reading this disclosure, preferred embodiments of the carbon composite material of the present invention described herein include at least some discontinuous fibers having a small diameter, and the total amount of fibers present is preferably lower than conventional carbon fibers. For example, the total amount of fibers is preferably in the range of about 50% to about 75% by weight based on the total amount of material. Thus, the total amount of fibers can be about 50% by weight, about 60% by weight, about 66% by weight, about 70% by weight, about 75% by weight, etc., according to various embodiments. Reducing the amount of fibers present advantageously reduces the impact and cost of manufacturing, distribution, and utilization of the material of the present invention and the corresponding products made therewith. This is possible due to the improved mechanical strength of the carbon composite material of the present invention described herein.

[0039] In various embodiments, the carbon fiber filaments 130 may be made from a plurality of polymer filaments that are produced by a spinning process, such as wet spinning, electrospinning, or melt spinning, and then treated with stabilization, physical stretching, oxidation, carbonization, graphitization, and any other suitable physical or chemical process. In some embodiments, the polymer filaments may be physically bundled into fibers prior to carbonization. In some other embodiments, the polymer filaments may be used to produce the carbon fiber filaments 130, which may then be physically bundled into one or more carbon fibers 110.

[0040] FIG. 1B is an SEM image 140 of a spun carbon-based composite according to one exemplary embodiment. As can be seen from FIG. 1B, the composite is an elongated structure comprising a plurality of carbon fibers oriented substantially parallel along their respective longitudinal axes. A careful review of FIG. 1B reveals the presence of carbon fiber filaments, preferably comprising graphene platelets comprising 3D graphene arranged along the outer surface(s) of the individual carbon fibers. Although not visible in FIG. 1B (but as shown in FIGS. 7A-7C and 8B, among others), the carbon fiber filaments are preferably embedded in the carbon fibers and reside in the interstitial spaces between the individual carbon fibers, thus imparting additional properties, such as improved mechanical strength and / or thermal conductivity, along a particular orientation, either through the longitudinal axis of the filaments, fibers, composites, etc., or perpendicular to the longitudinal axis, as will be understood by those of skill in the art upon reading this disclosure. Improved thermal conductivity may, in some embodiments, improve the oxidation of precursor materials comprising 3D graphene, further improving the resulting composite materials. Furthermore, the inclusion of 3D graphene in the precursor materials used to produce the compositions of matter described herein allows for increased tension during spin-based manufacturing processes, which in turn allows for smaller diameter fibers / filaments and better control over the micro- and macrostructure of the resulting fibers / filaments. Additionally, the inclusion of 3D graphene in the precursor materials may improve the rheological properties of the pre-spinning chemicals.

[0041] FIG. 2 illustrates an exemplary polymer filament 200 that may be used to manufacture the carbon fiber filament 130 of FIG. 1A, according to some embodiments. The polymer filament 200 is shown to include a longitudinal body 210, a cross-sectional surface 220, and a plurality of graphene platelets 230 within the longitudinal body 210. In some embodiments, the plurality of graphene platelets 230 may be dispersed within the longitudinal body 210 at various concentrations. In some embodiments, each of the graphene platelets 230 may contain single layer graphene (SLG), few layer graphene (FLG), multilayer graphene (MLG), or any combination thereof. In various embodiments, the plurality of graphene platelets 230 may be modified via chemical techniques such that one side of the graphene platelet 230 is polar and the opposite side of the graphene platelet 230 is non-polar (polarity not shown in FIG. 2 for simplicity). For example, the chemical techniques may include functionalization with chemical functional groups, adsorption with chemical compounds, or a combination thereof. In some cases, the chemical compounds adsorbed onto the surface of the graphene platelet 230 may include polycyclic aromatic hydrocarbons (PAHs) (not shown in FIG. 2 for simplicity).

[0042] In some implementations, the polymer filament 200 may be produced using a spinning dope spinning process. The spinning process may be wet spinning, electrospinning, melt spinning, or any combination thereof. In some other implementations, the polymer filament 200 may be produced using other suitable chemical processing techniques. The spinning dope may have a plurality of polymer particles in liquid form. The plurality of polymer particles may contain synthetic, semi-synthetic, or non-synthetic polymers. For example, the plurality of polymer particles may be or contain bread, pitch, rayon, or any combination thereof. In some cases, the plurality of graphene platelets 230 may be added to prepare the spinning dope. In some other cases, the plurality of graphene platelets 230 may be added when solidifying the spinning dope after extrusion. In various implementations, the weight percentage of the plurality of graphene platelets added may be less than 1% by weight. When extruded through one or more openings in the spinning process, the flow of spinning dope can induce multiple graphene platelets 230 to align parallel to one another, oriented with their longest sides along the length of the longitudinal body 210, and graphene layers stacking in a direction perpendicular to the length of the longitudinal body 210.

[0043] In this manner, the graphene platelets 230 may act as a structure-directing template to induce molecular chain alignment within the polymer. The graphene platelets 230 may also act as a nucleating agent to increase polymer solidification during the solidification process, thereby minimizing the size of voids or defects within the produced polymer filament 200. When the polymer filament 200 undergoes oxidation, carbonization, and graphitization to form the carbon fiber filament 130 of FIG. 1A, the enhanced alignment of molecular chains in the polymer is translated into an increased graphitic microstructure of the carbon fiber filament 130. Additionally, due to the dangling bonds on the graphene edges of the graphene platelets 230, the graphene platelets 230 may form bonds with the polymer within the polymer filament 200 to provide initiation points (or catalytic seeds) to facilitate the formation of the graphitic microstructure while consuming less thermal energy during the graphitization step. The elimination of internal porosity and increased graphitic microstructure may enhance the effective load-bearing cross-section of carbon fiber 110 in FIG. 1A, thereby enhancing the tensile strength of carbon fiber 110 in a direction perpendicular to the carbon fiber axis (90 degree tensile strength). See Table 1 below for an illustration of various strength measures and exemplary benefits according to one exemplary embodiment of the inventive concepts of the present disclosure.

[0044] For context and comparison, Figures 3A-3D depict conventional carbon fibers from cross-sectional views at various stages of manufacture and post-processing. It is immediately apparent that conventional carbon fibers contain a plurality of voids extending along their interior, typically oriented substantially parallel to their longitudinal axis. As shown in Figure 3A, such voids are present immediately after manufacture, when the fiber is in its "pristine state". To reduce the volume of these voids, following manufacture, there may be post-processing steps such as stretching the fiber (optionally at elevated temperatures) and / or annealing the fiber, although those skilled in the art will appreciate that this will impart corresponding mechanical weaknesses onto the fiber (particularly weaknesses to compression and / or tension in directions that deviate substantially from parallel to the longitudinal axis of the fiber). As shown in Figures 3B, 3C, and 3D, these procedures can reduce, but not eliminate, the void volume in the final conventional carbon fiber product.

[0045] Therefore, to further reduce the adverse effects associated with retaining voids in conventional carbon fibers, filler materials may be included in the carbon fibers. However, as is known in the art, attempts to correct the problems caused by voids are complex and often fail due to different chemistries for the filler composition and the carbon fibers (or their precursors). Thus, using fillers to address the mechanical weaknesses of conventional carbon fibers is not a satisfactory solution.

[0046] For example, fillers using conventional graphene-based materials (i.e., graphene materials mined from graphite) require chemical and / or mechanical methods to break down the material in a suitable manner. This process leaves significant defects in the "graphene" (e.g., holes in the basal plane, other lattice defects, etching chemistry left in the process, etc.), meaning that conventional graphene is typically weaker than fibers and / or polymers, resulting in minimal, if any, gain in improved mechanical strength. Other materials, such as quartz, silica, and talc powder, have limitations of brittleness and / or poor innate properties, and therefore add minimal value to composites. For example, conventional mica is characterized by a Young's modulus on the order of about 5.4 GPa, silica has a Young's modulus of less than 100 GPa, and talc powder has a Young's modulus of less than about 50 GPa. These types of materials typically detract from the overall system by introducing additional void content and / or inclusions in and / or around the fiber / polymer interface, or throughout the polymer.

[0047] Moreover, conventional materials typically contain undesirably high amounts of water: for example, moscovite is typically about 5% water by weight, and other inorganic materials often contain amounts ranging from greater than 1% to about 2% by weight.

[0048] In contrast, the precursor materials of the present invention utilized herein have a water content of 1.5% or less by weight, e.g., about 1.5% or less by weight, about 1.0% or less by weight, as would be understood by one of ordinary skill in the art upon reading this disclosure. In the final composite, water may be present in an amount of less than 0.5% by weight, e.g., about 0%, greater than 0% but less than about 0.1%, greater than 0% but less than about 0.25%, greater than 0% but less than about 0.33%, greater than 0% but less than about 0.5%, etc., as would be understood by one of ordinary skill in the art upon reading this disclosure.

[0049] In addition, the size of the filler particles becomes increasingly important relative to the fiber diameter. For example, when the size of the filler material becomes approximately 5 times (or more) larger than the fiber material (e.g., as is the case for mica flakes with millimeter-scale particle sizes, where the corresponding fiber size is on the 5-30 micrometer scale), this disparity can result in a desirable reduction in fiber / polymer bonding sites.

[0050] Dispersion throughout precursor materials is also a challenge for traditional fillers. Functionalization may enable these materials to be dispersible, but the resulting fillers may not improve the final system strength due to the issues / challenges mentioned above.

[0051] Additional considerations for conventional filler materials include viscosity, such as ionic viscosity, dynamic viscosity, state viscosity, cure viscosity, or similar metrics, which must be carefully controlled throughout the manufacture of conventional materials using carbon fiber.

[0052] Furthermore, the "cure index" measured at the ends of conventional carbon fiber systems typically exhibits less than desired cure, i.e., less than about 100% cure, because the conventional materials interfere with crosslinking of two-part systems for thermoset systems and / or impede the flow of polymers to mix / melt around the fibers, resulting in reduced wetting of the fibers by the filler material.

[0053] Increased oxygen from functionalization and / or increased oxygen introduced from the particle (typically in the form of free oxygen within the pores and / or increased surface area of ​​the particle) can adversely affect the overall system by: 1) slowing down the cure kinetics; 2) slowing down the cure rate; 3) undesirable increase / decrease in viscosity; 4) as well as any combination or secondary effects that lead to one of the above (e.g., antioxidant depletion or) deleterious modification of the chemicals embedded within the polymer. It should be noted that impurities in some of these materials can further minimize their utility and potential purposes of their use.

[0054] For example, exemplary conventional filler materials that have been found to be undesirable for use with carbon fibers include other graphenes, carbon allotropes, CNTs, carbon black, silica, moscovite, quartz, silicates, and other organics / inorganics. These materials have surface chemistries that produce adverse results when attempting to functionalize the surface, or exhibit properties such as undesirably high amounts of molecular oxygen, undesirably large or small aspect ratios, having mechanical strengths (e.g., as may be measured according to any metric described herein and equivalents thereof, as would be understood by one of skill in the art upon review of this disclosure) that are lower than the mechanical strength of the fiber(s) being repaired or reinforced, or any combination thereof.

[0055] In contrast, the inventive concepts of the present disclosure approach problems with mechanical weaknesses by directly incorporating support materials (e.g., carbon filaments, 3D graphene, etc. as described herein) with carbon fibers (and / or their precursors) that have compatible chemistries, particularly surface chemistries, due to the similar nature of the compounds used (e.g., pitch, PAN, rayon, etc. as described herein and by various approaches).

[0056] For example, carbon fibers are generally hydrophobic, while the polymers used in conjunction therewith are hydrophilic. Carbon filaments, particularly 3D graphene as described in accordance with the inventive concepts presented herein, bridge this gap and allow substantial improvements in terms of the mechanical strength of the resulting fibers. Additionally, 3D graphene materials can be engineered to have different surface chemistries, e.g., hydrophilic tuning, leading to hydrophobic and hydrophilic surfaces within the same 3D graphene structure. This type of engineering allows 3D graphene to bridge between carbon fiber (layer 1)-polymer matrix-carbon fiber (layer 2)-other structures, e.g., via interfacial bonding. 3D graphene also advantageously acts as a catalyst for pyrolysis, particularly of pitch, further facilitating the production of stronger materials. Additionally, the utilization of pitch for fibers has been limited by the inferior resulting mechanical properties of fibers produced with pitch, however, pitch, e.g., derived from PAN, with properties equal / superior to other carbon fibers, with the addition of 3D graphene to reinforce said fibers, is considered an advantageous aspect of the inventive concepts of the present disclosure.

[0057] Moreover, the ability to tailor and control the orientation of the carbon filaments disposed within the carbon fiber provides substantial improvements in compressive strength and tensile strength applied at angles that deviate from substantially parallel to the longitudinal axis of the carbon fiber. Of course, other improvements such as modulus strength, in-plane shear strength, interlaminar shear strength, flexural strength, etc., as described herein, are also realized through the implementation of the inventive materials and techniques described herein.

[0058] Additionally, the ability to disperse carbon filaments and 3D graphene throughout the composition allows for additional anchoring points and improved fiber / polymer interactions compared to traditional carbon fiber formulations and manufacturing methods.

[0059] Referring now to FIG. 3E, an exemplary carbon fiber filament 300 according to some implementations of the inventive concepts of the present disclosure is shown according to a simplified schematic diagram highlighting the orientation of the carbon fiber filament. The carbon fiber filament 300, which may be one example of the carbon fiber filament 130 of FIG. 1A, may have a plurality of graphene platelets sized (or coated) on the outer surface of the carbon fiber filament 300. In some examples, the carbon fiber filament 300 may be manufactured by techniques and processes disclosed herein, such as wet spinning, electrospinning, melt spinning, hybrid methods, e.g., dry jet / wet spinning, or any suitable combination or equivalent(s) thereof, as will be understood by those of skill in the art upon reading this disclosure. In other cases, the carbon fiber may be a commercially available product.

[0060] In the example of FIG. 3E, the carbon fiber filament 300 is shown to include an exterior surface 320 and a plurality of graphene platelets 330 sized on the exterior surface 320. In some implementations, each of the graphene platelets 330 may contain single layer graphene (SLG), few layer graphene (FLG), multilayer graphene (MLG), or any combination thereof. In various implementations, each of the graphene platelets 330 may be modified via chemical techniques such that one side of the graphene platelet 330 is polar and the opposite site of the graphene platelet 330 is non-polar. For example, the chemical techniques may include functionalization with chemical functional groups, adsorption with chemical compounds, or a combination thereof. In some cases, the chemical compounds adsorbed on the surface of the graphene platelet 330 may include PAHs (not shown in FIG. 3E for simplicity) that are adsorbed to one or more adsorption sites on a first side of the graphene platelet 330.

[0061] According to various applications, graphene platelets or other forms of 3D graphene may be present in a range of less than 1% to about 100% by weight of the fiber. For example, the 3D graphene or graphene platelets may be present in less than about 1%, about 1%, about 2%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 33%, about 40%, about 50%, about 60%, about 66%, about 70%, about 75%, about 80%, about 90%, about 95%, about 98%, about 99%, about 99.9%, or any range including these values ​​and / or values ​​therebetween.

[0062] In some implementations, the 3D and / or graphene platelets may be present (e.g., via sizing) on ​​the outer surface(s) of the fiber in an amount ranging from less than 1% to about 20% by weight. For example, the amount of 3D graphene and / or graphene platelets sized on the outer surface(s) of the fiber may be less than about 1% by weight, about 1% by weight, about 2% by weight, about 5% by weight, about 7.5% by weight, about 10% by weight, about 12.5% ​​by weight, about 15% by weight, about 17.5% by weight, about 20% by weight, or any range including and / or values ​​therebetween. In one particularly preferred embodiment, the weight percentage of the plurality of graphene platelets sized on the outer surface 320 may be less than 1% by weight of the total weight of the fiber.

[0063] In other embodiments, graphene and / or 3D graphene precursor materials may comprise less than 1% to about 100% by weight of the fibers. For example, 3D graphene or graphene platelets may be present in less than about 1% by weight, about 1% by weight, about 2% by weight, about 5% by weight, about 10% by weight, about 15% by weight, about 20% by weight, about 25% by weight, about 30% by weight, about 33% by weight, about 40% by weight, about 50% by weight, about 60% by weight, about 66% by weight, about 70% by weight, about 75% by weight, about 80% by weight, about 90% by weight, about 95% by weight, about 98% by weight, about 99% by weight, about 99.9% by weight, or any range including these values ​​and / or values ​​therebetween.

[0064] As shown in FIG. 3E, the plurality of graphene platelets 330 may have various lengths and may be sized on the exterior surface 320 at various concentrations. As an example, a first region 334 may have a plurality of graphene platelets 330 arranged closer to one another as compared to the plurality of graphene platelets in a second region 332, such that the first region 334 has a higher concentration of graphene platelets 330 than the second region 332. In some implementations, the plurality of graphene platelets 330 may be sized on the exterior surface 320 at various angles from 0 degrees to 90 degrees relative to the fiber axis. However, it should be understood that according to various embodiments of the inventive concepts described herein, the fibers may be reinforced via reinforcing structures, such as those present within the bulk volume of the fibers, sized (or otherwise disposed) on the surface(s) of the fibers, or present in proximity to the fibers, such as by being present within a resin or binder matrix structurally bonded ...

[0065] Thus, the graphene platelets 330 may prevent adhesion failure that typically occurs between the carbon fiber filaments 300 and the surrounding polymer in the binder matrix 120 of FIG. 1A. In various embodiments, the graphene platelets 330 may act as anchor points bridging the carbon fiber filaments 300 and the binder matrix. For example, when a stress associated with a load is applied to the carbon fiber composite 100 of FIG. 1A in a direction perpendicular to the fiber axis, the polar side of the graphene platelets 330 may interact well with the hydrophilic binder matrix, and the non-polar side of the graphene platelets 330 may remain strongly bonded to the carbon fiber filaments 300, ensuring a "bridge" between the carbon fiber filaments 300 and the binder matrix. In this manner, the "bridge" prevents the carbon fiber filaments 300 from being separated from the carbon fiber composite, thereby improving the mechanical strength of the carbon fiber composite.

[0066] Again, while the exemplary embodiment depicted in FIG. 3E is described herein as having a plurality of “sized” graphene platelets 330 on its exterior surface 320, it should be understood that in various approaches, carbon fiber filaments and / or graphene platelets may additionally or alternatively be embedded in or intermeshed with one another throughout the interior volume of a given carbon fiber and / or the interstitial spaces between the carbon fibers, as shown and described in more detail herein with respect to FIGS. 7A-7C and 8B.

[0067] FIG. 4 illustrates an exemplary graphene platelet 400 that may be used to manufacture the polymer filament of FIG. 2 or the carbon fiber filament of FIG. 3E, according to some embodiments. In some embodiments, the graphene platelet 400 may be modified via chemical techniques such that one side of the graphene platelet 400 is polar and the opposite side of the graphene platelet 400 is non-polar. For example, the chemical techniques may include functionalization with chemical functional groups, adsorption with chemical compounds, or a combination thereof. In some cases, the chemical compounds adsorbed onto the surface of the graphene platelet 400 may include PAHs.

[0068] In the example of FIG. 4, graphene platelet 400 is shown to include four graphene layers 410-440 stacked (e.g., vertically or substantially vertically) on top of one another and PAH 412 adsorbed on one or more adsorption sites on graphene layer 410. In other embodiments, graphene platelet 400 may include other numbers of graphene layers and PAH 412 may be adsorbed on another graphene layer of graphene platelet 400. By way of example, PAH 412 may be naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, anthracene, benzo(a)anthracene, chrysenbenzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene dibenzo(a,h)anthracene, benzo(g,h,i)perylene, indeno(1,2,3-cd)pyrene, or any combination thereof. The adsorption of PAH412 onto the graphene platelets 400 can affect one or more properties of the carbon fiber 110 of FIG. 1A. These properties can include, but are not limited to, larger graphitic structures in the fiber microstructure, enhanced tensile strength, and enhanced adhesion between the fiber and the binder matrix. In this manner, carbon fiber composites produced and / or reinforced using the techniques disclosed herein can absorb and / or dissipate energy and stress associated with applied forces, pressures, and loads, thereby improving the overall mechanical properties of the carbon fiber composite 100. Some of the improved mechanical properties are summarized in Table 1 below. In some embodiments, the mechanical properties of Applicant's ("LYTEN") carbon fiber composites produced according to the subject matter and techniques disclosed herein are superior to those demonstrated by the control carbon fiber composite by varying in the range of about 2.5% to 41.7%, inclusive. [Table 1]

[0069] 5 is an SEM image 500 of an exemplary polymer formulation including three-dimensional (3D) graphene, according to one embodiment. As can be seen from the various nodules appearing on the surface of the formulation, the 3D graphene is incorporated into the bulk of the material and its outer surface, providing multiple active sites for polymer / graphene interactions and optional functionalization of the material, e.g., via surface oxidation, nitridation, for doping, surface modification, and material densification, as would be understood by one of skill in the art upon reading this disclosure.

[0070] FIG. 6 is a micrograph image 600 of the interior volume of a carbon fiber having 3D graphene ligands intermeshed (or equivalently, "embedded" as described herein) throughout the bulk of the fiber, according to one embodiment. As used herein, the terms "ligand", "ligands", and the like, should be understood to refer to substructures that extend outwardly or branch out (e.g., in a substantially fractal configuration) from a core structure, such as a graphene platelet or a carbo-based material, with or without a chemical trace. In a preferred embodiment, the "ligand" includes or is a substantially carbon-based structure, in which some or all of the carbon atoms are sp 3 The ligands may exhibit orbital hybridization. Additionally, the ligands may also exhibit chemical traces, chemical functionalities, coupling agents, or other chemical modifications / methods. Also preferably, the ligands may be characterized by a substantially elongated structure, e.g., less than 10% of the fiber diameter, or more than 100% of the fiber diameter, or anywhere in between, by various approaches.

[0071] The intermeshing of ligands in the bulk volume of the fibers provides multiple "anchors" to which individual fibers can be cross-linked, reinforcing composites made from the carbon fibers of the present invention as disclosed herein, according to several approaches. In addition, the incorporation of graphene platelets and / or ligands within the bulk volume of the individual fibers advantageously reinforces the structural integrity of the individual fibers, particularly with respect to compressive and tensile strength applied in a direction that substantially deviates from parallel to the longitudinal axis of the fiber. However, according to various embodiments of the inventive concepts described herein, it should be understood that the fibers can be reinforced, for example, by being present in a resin or binder matrix structurally bonded to the fiber, via a reinforcing structure present within the bulk volume of the fiber, sized (or otherwise disposed) on the surface(s) of the fiber, or present in close proximity to the fiber, for example, by a filamentous carbon-based structure as described herein.

[0072] For example, Figure 6 depicts multiple white and black dots distributed throughout the bulk of the overall structure. The black dots indicate surface roughness, facilitating surface modification, for example, to improve mechanical adhesion via friction or other mechanical locking mechanisms. The white dots, in turn, represent surface chemistry, which improves the chemical interface of the surface(s) of the fiber and / or binder matrix. Examples of such improvements include functionalization with various functional groups or moieties, inclusion of coupling agents, etc., as will be understood by those of skill in the art upon reading this disclosure.

[0073] Moreover, one skilled in the art will appreciate that, as an engineered material, three-dimensional graphene and control of the formation process allows for tailoring the surface of the material to improve binding with a variety of different compounds of various types, providing a tunable surface chemistry. Furthermore, due to the engineered nature of the structure, in selected embodiments, the three-dimensional graphene may impart the ability to bind with coupling agents and hold together fibers and polymers (particularly polymers having three-dimensional graphene contained / sized thereon), imparting improved mechanical strength to the resulting composite material.

[0074] 7A is an image 700 showing a plurality of carbon fibers 702 intermeshed with 3D graphene from a cross-sectional view according to an exemplary embodiment. The diagram shown in FIG. 7A shows the 3D graphene intermeshed with the individual fibers 702 throughout the structure as well as filling the interstitial spaces 704 between the individual fibers according to an exemplary embodiment.

[0075] FIG. 7B is an image 710 of one of the carbon fibers shown in FIG. 7A, illustrating 3D graphene intermeshing with both the bulk and the outer surface of the carbon fiber, according to one embodiment. As can be seen from the image, the ligands 706 of the 3D graphene extend beyond the outer surface of the individual fiber in which they are incorporated. These ligands 706 effectively "bridge" the various fibers shown in FIG. 7A, reinforcing the multi-fiber structure as a whole. In embodiments where a binder matrix is ​​included in the composition (e.g., occupying some or all of the volume within the interstitial spaces 704 between the fibers), these ligands 706 may be incorporated or intermeshed with the matrix, providing further improvements to the structural integrity of the composite.

[0076] FIG. 7C is an SEM image 720 showing an exemplary ligand structure for 3D graphene according to one approach.

[0077] FIG. 8A is a micrograph image 800 showing a conventional carbon fiber from a cross-sectional view without carbon fiber filaments or particles disposed therein, and FIG. 8B is a micrograph image 810 showing a carbon fiber of the present invention having a plurality of carbon fiber filaments or particles (dark spots) disposed therein from a cross-sectional view according to an exemplary embodiment.

[0078] 9A is a graph comparing the compressive strength of PAN-based polymer filaments and PAN / graphene-0.075 composite carbon fibers containing about 0.075 wt.% graphene at various stages of manufacture according to one approach. As is evident from the graph, conventional PAN and the PAN / graphene-0.075 material of the present invention exhibit similar compressive strengths both in precursor form and upon oxidation. Both the PAN and the PAN / graphene-0.075 material of the present invention also exhibit substantially improved compressive strengths upon carbonization, as expected. However, the compressive strength of the carbonized PAN / graphene-0.075 material is nearly four times that of the conventional PAN-based composition that has been carbonized. Without wishing to be bound by any particular theory, the inventors believe that the improved compressive strength is provided through the presence of a network of carbon filaments, 3D graphene, or both throughout the carbon fiber, having a distribution of orientation angles, preferably including filaments and / or 3D graphene platelets oriented at angles substantially parallel to the longitudinal axis of the carbon fiber, as well as filaments and / or 3D graphene platelets oriented at angles that substantially deviate from parallel to the longitudinal axis of the carbon fiber.

[0079] FIG. 9B is a graph comparing the Young's modulus of PAN-based polymer filaments and PAN / graphene-0.075 composite carbon fibers at various stages of manufacture according to one approach. As shown in FIG. 9A, the moduli of precursor and oxidized PAN-based polymer filaments and PAN / graphene-0.075 composite fibers are relatively low and similar to each other. Again, as with the compressive strength, the carbonized PAN / graphene-0.075 composite carbon fibers exhibit a modulus approximately three times that of the carbonized PAN-based polymer filaments, but carbonization significantly increases the modulus of both materials. The same mechanism described above for improved compressive strength is believed to be the source of the improved modulus in the inventive carbon fiber composite materials described herein.

[0080] FIG. 9C is a graph comparing the strain of PAN-based polymer filaments with that of PAN / graphene-0.075 composite carbon fibers at various stages of manufacture according to one approach. As expected, the precursor materials of both compositions exhibit the highest strain, but the strain observed in the PAN / graphene-0.075 precursor material is nearly 2.5 times the magnitude of that of the PAN-based precursor material. Upon oxidation, the strain is effectively eliminated in the PAN-based polymer filaments, still about 2.5 times that of the oxidized PAN-based polymer filaments, but significantly reduced in the PAN / graphene-0.075 material. Finally, upon carbonization, both materials exhibit virtually negligible strain.

[0081] FIG. 10A shows a flow chart depicting an exemplary operation for producing a carbon fiber filament, according to some embodiments. In various embodiments, the operation 1000 may be performed via wet spinning, electrospinning, melt spinning, or any combination thereof. In other embodiments, the operation 1000 may be performed via another suitable chemical processing technique. In some embodiments, the polymer particles may be dissolved in a liquid solvent to provide a liquid form. In some other embodiments, the polymer particles may be in a molten state, and the molten state is in a liquid form. In various embodiments, the weight percentage of the graphene platelets added may be less than 1 wt.%.

[0082] In some embodiments, each of the plurality of graphene platelets may contain single layer graphene (SLG), few layer graphene (FLG), multilayer graphene (MLG), or any combination thereof. In various embodiments, the plurality of graphene platelets may be modified via chemical techniques such that each graphene platelet may have polarity on one side and non-polarity on the opposite site. For example, chemical techniques may include functionalization with chemical functional groups, adsorption with chemical compounds, or a combination thereof. In some cases, each graphene platelet may have PAHs adsorbed on one or more adsorption sites on a first side of the graphene platelet. By way of example, the PAH can be naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, anthracene, benzo(a)anthracene, chrysenbenzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene dibenzo(a,h)anthracene, benzo(g,h,i)perylene, indeno(1,2,3-cd)pyrene, or any combination thereof.

[0083] In some embodiments, the operations 1000 begin at block 1002 with receiving a spinning dope containing a plurality of polymer particles and a plurality of graphene platelets in liquid form. The operations 1000 continue at block 1004 with extruding the spinning dope through one or more openings. In some examples, the one or more openings may be a spinneret having a plurality of holes. In some other examples, the one or more openings may be the tip of a needle or syringe. The operations 1000 continue at block 1006 with solidifying the extruded spinning dope into one or more polymer filaments. In some embodiments, the extruded spinning dope may be immersed in a liquid coagulation bath for solidification. In some other embodiments, the extruded spinning dope may be subjected to cooling, solvent evaporation, or other suitable treatment for solidification.

[0084] FIG. 10B shows a flow chart depicting exemplary operations for producing carbon fiber filaments, according to some embodiments. In various embodiments, operation 1020 may be performed simultaneously with solidifying the extrusion spinning dope into one or more polymer filaments in block 1006 of FIG. 10A. In some aspects, operation 1020 begins with exposing the extrusion spinning dope to a plurality of graphene platelets in block 1022. In some embodiments, each of the graphene platelets may contain single layer graphene (SLG), few layer graphene (FLG), multilayer graphene (MLG), or any combination thereof. In various embodiments, the plurality of graphene platelets may be modified via chemical techniques such that each graphene platelet may have polarity on one side and non-polarity on the opposite site. For example, chemical techniques may include functionalization with chemical functional groups, adsorption with chemical compounds, or a combination thereof. In some cases, each graphene platelet may have PAHs adsorbed on one or more adsorption sites on a first side of the graphene platelet. By way of example, the PAH can be naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, anthracene, benzo(a)anthracene, chrysenbenzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene dibenzo(a,h)anthracene, benzo(g,h,i)perylene, indeno(1,2,3-cd)pyrene, or any combination thereof.

[0085] FIG. 10C shows a flow chart depicting exemplary operations for producing carbon fiber filaments, according to some embodiments. In various embodiments, operation 1030 may be performed after solidifying the extrusion spinning dope into one or more polymer filaments in block 1006 of FIG. 10A. In some aspects, operation 1030 begins with oxidizing one or more polymer filaments at a first temperature in block 1032. In various embodiments, operation 1030 may be performed in a thermal reactor or any other suitable reaction chamber with applied heat. Operation 1030 continues with carbonizing the one or more polymer filaments at a second temperature in block 1034. Operation 1030 continues with graphitizing the one or more polymer filaments at a third temperature in block 1036. In various embodiments, the third temperature is greater than the second temperature, and the second temperature is greater than the first temperature.

[0086] FIG. 11 shows a flow chart depicting another exemplary operation for producing a carbon fiber filament according to some other embodiments. In some aspects, the operation 1100 begins at block 1102 with applying a sizing layer containing a plurality of graphene platelets to a carbon fiber filament. In some examples, the carbon fiber filament may be produced by techniques and processes disclosed herein, such as wet spinning, electrospinning, melt spinning, or any combination thereof. In other cases, the carbon fiber may be a commercially available product from a commercial manufacturer. In some embodiments, each of the graphene platelets may contain single layer graphene (SLG), few layer graphene (FLG), multilayer graphene (MLG), or any combination thereof. In various embodiments, the plurality of graphene platelets may be modified via chemical techniques such that each graphene platelet may have polarity on one side and non-polarity on the opposite site. For example, the chemical techniques may include functionalization with chemical functional groups, adsorption with chemical compounds, or a combination thereof. In some cases, each graphene platelet may have a PAH adsorbed on one or more adsorption sites on the first side of the graphene platelet. As an example, the PAH may be naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, anthracene, benzo(a)anthracene, chrysenbenzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene dibenzo(a,h)anthracene, benzo(g,h,i)perylene, indeno(1,2,3-cd)pyrene, or any combination thereof. In various embodiments, the weight percentage of the graphene platelets added may be less than 1 wt%. In this way, the graphene platelets may strengthen the "bridge" between the carbon fiber filament and the surrounding binder matrix when stress associated with a load is applied. Such enhanced "crosslinking" can prevent adhesion failure in the interphase zone between the carbon fiber filaments and the binder matrix, thereby reinforcing the carbon fiber composite comprised of the carbon fiber filaments and the binder matrix.

[0087] In various embodiments, multiple carbon fiber filaments may be physically bundled together to form one or more carbon fibers, as shown in Figure 1A. By having multiple graphene platelets that reinforce the internal microstructure of each filament and improve the adhesion between each filament and the binder matrix, the mechanical properties of the resulting carbon fiber composite, as shown in Figure 1A, may be improved. The improved mechanical properties may include, but are not limited to, tensile strength, tensile modulus, and compressive strength parallel to the carbon fiber axis, tensile strength, tensile modulus, and compressive strength perpendicular to the carbon fiber axis, in-plane shear strength and modulus, interlaminar shear strength, and flexural strength and modulus.

[0088] It should be understood that the arrangements of components depicted in the described figures are exemplary and that other arrangements are possible, and that the various system components (and means) described below, illustrated in the various block diagrams, and defined by the claims represent logical components in some systems configured in accordance with the subject matter disclosed herein.

[0089] According to one embodiment, the composition of matter includes carbon fibers having a plurality of carbon fiber filaments disposed therein, at least some of the plurality of carbon fiber filaments each independently characterized by a longitudinal axis oriented at an angle that deviates substantially from parallel to the longitudinal axis of the carbon fiber. Optionally, the longitudinal axes of at least some of the plurality of carbon fiber filaments each independently characterized by a substantially random distribution of orientation angles that deviate from parallel to the longitudinal axis of the carbon fiber. Similarly, other longitudinal axes of the plurality of carbon fiber filaments may be aligned substantially parallel to the longitudinal axis of the carbon fiber. At least some of the carbon fiber filaments may be discontinuous, while other carbon fiber filaments may be continuous. For example, the carbon fiber filaments may be characterized by an aspect ratio ranging from about 100:1 to about 1000:1. Additionally, at least some of the carbon fiber filaments may independently comprise one or more graphene platelets. In such an approach, at least some of the one or more graphene platelets may comprise three-dimensional (3D) graphene, and / or at least some of the carbon atoms of the 3D graphene are sp 3The graphene platelets may be characterized by orbital hybridization. The plurality of graphene platelets may each independently comprise single layer graphene (SLG), few layer graphene (FLG), multilayer graphene (MLG), or any combination thereof. At least some of the graphene platelets may comprise one or more polycyclic aromatic hydrocarbons (PAHs) adsorbed to one or more adsorption sites on one or more surfaces of the graphene platelets. Optionally, the orientation planes of at least some of the graphene platelets may each independently be oriented at an angle that substantially deviates from parallel to the longitudinal axis of the carbon fibers. The 3D graphene may be present in an amount ranging from less than 1 weight percent of the total weight of the carbon fibers to about 100 weight percent of the total weight of the carbon fibers in various approaches. Additionally, at least some of the plurality of carbon fiber filaments may be sized on one or more outer surfaces of the carbon fibers. The composition of matter may be provided in the form of a plurality of carbon fibers aligned substantially parallel along their longitudinal axes, with at least some of the carbon fiber filaments preferably crosslinking some or all of the plurality of carbon fibers. Similarly, the composition of matter may include a binder matrix having a second plurality of carbon fiber filaments disposed therein, at least some of the second plurality of carbon fiber filaments preferably cross-linking some or all of the plurality of carbon fibers. Moreover, the composition may substantially exclude oxygen.

[0090] According to another embodiment, the composition of matter includes carbon fibers having a plurality of graphene platelets disposed therein, at least some of the graphene platelets comprising three-dimensional (3D) graphene. The 3D graphene may be present in an amount ranging from less than 1 weight percent of the total weight of the carbon fibers to about 100 weight percent of the total weight of the carbon fibers, in various approaches. Optionally, at least some of the carbon atoms in the 3D graphene are sp 3The 3D graphene is characterized by orbital hybridization. Preferably, the 3D graphene comprises a plurality of ligands incorporated into the bulk of the carbon fiber, the outer surface of the carbon fiber, or both the bulk and the outer surface of the carbon fiber. The oriented planes of at least some of the graphene platelets may each independently be oriented at an angle that substantially deviates from parallel to the longitudinal axis of the carbon fiber. The plurality of graphene platelets may each independently comprise single layer graphene (SLG), few layer graphene (FLG), multilayer graphene (MLG), or any combination thereof. At least some of the graphene platelets may comprise one or more polycyclic aromatic hydrocarbons (PAHs) adsorbed on one or more adsorption sites on one or more surfaces of the graphene platelets. Additionally, at least some of the plurality of graphene platelets may be sized on one or more outer surfaces of the carbon fiber. The composition of matter may be provided in the form of a plurality of carbon fibers aligned substantially parallel along their longitudinal axes, with at least some of the graphene platelets preferably crosslinking some or all of the plurality of carbon fibers. Additionally or alternatively, the carbon fiber may have a plurality of carbon fiber filaments disposed therein, at least some of the plurality of carbon fiber filaments each independently characterized by a longitudinal axis oriented at an angle that deviates substantially from parallel to the longitudinal axis of the carbon fiber. Optionally, the longitudinal axes of at least some of the plurality of carbon fiber filaments each independently characterized by a substantially random distribution of orientation angles that deviate from parallel to the longitudinal axis of the carbon fiber. Similarly, other longitudinal axes of the plurality of carbon fiber filaments may be aligned substantially parallel to the longitudinal axis of the carbon fiber. At least some of the carbon fiber filaments may be discontinuous, while other carbon fiber filaments may be continuous. For example, the carbon fiber filaments may be characterized by an aspect ratio ranging from about 100:1 to about 1000:1. Additionally, at least some of the plurality of carbon fiber filaments may be sized on one or more outer surfaces of the carbon fiber.The composition of matter may include an optional binder matrix having a second plurality of carbon fiber filaments disposed therein, at least some of the second plurality of carbon fiber filaments preferably cross-linking some or all of the plurality of carbon fibers. Moreover, the composition may substantially exclude oxygen.

[0091] According to yet another embodiment, the composition of matter comprises carbon fibers having a plurality of carbon fiber filaments sized on one or more outer surfaces, characterized in that the carbon fiber filaments either comprise graphene platelets and have some or all of the longitudinal axes of the carbon fiber filaments oriented at an angle substantially deviating from parallel to the longitudinal axis of the carbon fiber, or comprise graphene platelets and have some or all of the longitudinal axes of the carbon fiber filaments oriented at an angle substantially deviating from parallel to the longitudinal axis of the carbon fiber. At least some of the graphene platelets may comprise one or more polycyclic aromatic hydrocarbons (PAHs) adsorbed on one or more adsorption sites on one or more surfaces of the graphene platelets. Preferably, at least some of the graphene platelets comprise three-dimensional (3D) graphene, and at least some of the carbon atoms of the 3D graphene are sp 3The 3D graphene is characterized by orbital hybridization. The 3D graphene may be present in an amount ranging from less than 1 weight percent of the total weight of the carbon fibers to about 100 weight percent of the total weight of the carbon fibers in various approaches. Preferably, the 3D graphene comprises a plurality of ligands incorporated into the bulk of the carbon fibers, the outer surface of the carbon fibers, or both the bulk and the outer surface of the carbon fibers. The orientation planes of at least some of the graphene platelets may each independently be oriented at an angle that substantially deviates from parallel to the longitudinal axis of the carbon fibers. The plurality of graphene platelets may each independently comprise single layer graphene (SLG), few layer graphene (FLG), multilayer graphene (MLG), or any combination thereof. At least some of the graphene platelets may comprise one or more polycyclic aromatic hydrocarbons (PAHs) adsorbed on one or more adsorption sites on one or more surfaces of the graphene platelets. Additionally, at least some of the plurality of graphene platelets may be sized on one or more outer surfaces of the carbon fibers. The composition of matter may be provided in the form of a plurality of carbon fibers aligned substantially parallel along their longitudinal axes, with at least some of the carbon fiber filaments (which may also include graphene platelets) preferably cross-linking some or all of the plurality of carbon fibers. Additionally or alternatively, the carbon fiber may have a plurality of carbon fiber filaments disposed therein, with at least some of the plurality of carbon fiber filaments each independently characterized by a longitudinal axis oriented at an angle that substantially deviates from parallel to the longitudinal axis of the carbon fiber. Optionally, the longitudinal axes of at least some of the plurality of carbon fiber filaments each independently characterized by a substantially random distribution of orientation angles that deviate from parallel to the longitudinal axis of the carbon fiber. Similarly, other longitudinal axes of the plurality of carbon fiber filaments may be aligned substantially parallel to the longitudinal axis of the carbon fiber. At least some of the carbon fiber filaments may be discontinuous, while other carbon fiber filaments may be continuous. For example, the carbon fiber filaments may be characterized by an aspect ratio ranging from about 100:1 to about 1000:1.Additionally, at least some of the plurality of carbon fiber filaments may be sized on one or more outer surfaces of the carbon fibers. The composition of matter may include an optional binder matrix having a second plurality of carbon fiber filaments disposed therein, at least some of the second plurality of carbon fiber filaments preferably cross-linking some or all of the plurality of carbon fibers. Moreover, the composition may substantially exclude oxygen.

[0092] According to yet another embodiment, the composition of matter includes carbon fibers and a binder matrix, the binder matrix being structurally bonded to the carbon fibers via either a plurality of carbon fiber filaments in the binder matrix, a plurality of graphene platelets in the binder matrix, or both a plurality of carbon fiber filaments in the binder matrix and a plurality of graphene platelets in the binder matrix. Preferably, the plurality of carbon fiber filaments in the binder matrix and / or the plurality of graphene platelets in the binder matrix are structurally bonded to the carbon fibers by bridging the binder matrix and the carbon fibers. The carbon fibers may include a second plurality of carbon fiber filaments disposed therein. In various approaches, at least some of the plurality of carbon fiber filaments and / or the second plurality of carbon fiber filaments are each independently characterized by a longitudinal axis oriented at an angle that substantially deviates from parallel to the longitudinal axis of the carbon fibers. Optionally, the longitudinal axes of at least some of the plurality of carbon fiber filaments and / or the second plurality of carbon fiber filaments each independently feature a substantially random distribution of orientation angles that deviate from parallel to the longitudinal axis of the carbon fibers. Similarly, the longitudinal axes of the other of the plurality of carbon fiber filaments and / or the second plurality of carbon fiber filaments may be aligned substantially parallel to the longitudinal axis of the carbon fibers. At least some of the carbon fiber filaments and / or the second carbon fiber filaments may be discontinuous and others of the carbon fiber filaments and / or the second carbon fiber filaments may be continuous. For example, the carbon fiber filaments and / or the second carbon fiber filaments may feature an aspect ratio ranging from about 100:1 to about 1000:1. Moreover, at least some of the carbon fiber filaments and / or the second carbon fiber filaments may independently include one or more graphene platelets. In such an approach, at least some of the one or more graphene platelets may include three-dimensional (3D) graphene, and / or at least some of the carbon atoms of the 3D graphene are sp 3The graphene platelets may be characterized by orbital hybridization. The plurality of graphene platelets may each independently comprise single layer graphene (SLG), few layer graphene (FLG), multilayer graphene (MLG), or any combination thereof. At least some of the graphene platelets may comprise one or more polycyclic aromatic hydrocarbons (PAHs) adsorbed to one or more adsorption sites on one or more surfaces of the graphene platelets. Optionally, the orientation planes of at least some of the graphene platelets may each independently be oriented at an angle that substantially deviates from parallel to the longitudinal axis of the carbon fibers. The 3D graphene may be present in an amount ranging from less than 1 weight percent of the total weight of the carbon fibers to about 100 weight percent of the total weight of the carbon fibers in various approaches. Additionally, at least some of the plurality of carbon fiber filaments, the second plurality of carbon fiber filaments, and / or the graphene platelets may be sized on one or more outer surfaces of the carbon fibers. The composition of matter may be provided in the form of a plurality of carbon fibers aligned substantially parallel along their longitudinal axes, with at least some of the carbon fiber filaments and / or the second carbon fiber filaments preferably cross-linking some or all of the plurality of carbon fibers. Additionally or alternatively, graphene platelets in the binder matrix and / or the carbon fiber(s) may cross-link the plurality of carbon fibers. Moreover, the composition may substantially exclude oxygen.

[0093] Moreover, one or more of the system components (and means) may be realized, in whole or in part, by at least some of the components depicted in the configurations depicted in the described figures. In addition, at least one of these components may be implemented at least in part as electronic hardware components and thus constitute a machine, while 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.

[0094] More specifically, at least one component defined by the claims is implemented, at least in part, as an electronic hardware component, such as an instruction-executing machine (e.g., a processor-based or processor-containing machine), and / or as a specialized circuit 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 entirely, 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 the claims.

[0095] To facilitate understanding of the subject matter described herein, many aspects are described in terms of a sequence of actions. At least one of these aspects defined by the claims is performed by electronic hardware components. For example, it will be recognized that various actions can be performed by specialized circuits or circuitry, by program instructions executed by one or more processors, or by a combination of both. The description herein of any sequence of actions is not intended to imply that the particular order described must be followed to perform the sequence. All methods described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

[0096] 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 claims below) should be construed to include both the singular and the plural, unless otherwise indicated herein or clearly contradicted by the context. The recitation of ranges of values ​​herein is 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 herein as if it were individually recited herein. Moreover, the foregoing description is for illustrative purposes only and not for limiting purposes, as the scope of protection sought is defined by the claims set forth below and equivalents thereof where entitled. The use of any and all examples or exemplary language (e.g., "such as") presented herein is intended merely to better describe the subject matter, and does not limit the scope of the subject matter, unless otherwise claimed. In both the claims and the specification, the use of the term "based on" and other similar phrases indicating a condition for producing a result is not intended to exclude other conditions for producing that result. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the claimed invention.

[0097] Similarly, phrases referring to "at least one of," "one or more of," "some or all of," or equivalent references to a list of items refer to any combination of those items, including a single element. As an example, "at least one of a, b, or c" is intended to cover a, b, c, ab, ac, bc, and abc. The various example logic, logic blocks, modules, circuits, and algorithmic processes described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. Interchangeability of hardware and software has been generally described in terms of functionality and is illustrated in the various example components, blocks, modules, circuits, and processes discussed above. Whether such functionality is implemented in hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0098] Moreover, the term "about" as used herein, particularly with reference to a numerical range, should be understood to include the recited value and its +10% margin. For example, "about 1.0" should be understood to include values ​​in the range of 0.9 to 1.1. Similarly, "about 500" should be understood to include values ​​in the range of 450 to 550. Thus, those skilled in the art will clearly recognize the full range included in any recitation of numerical values ​​herein modified by the term "about" according to various approaches.

[0099] Various modifications to the embodiments described in this disclosure may be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the present disclosure. Thus, the claims are not intended to be limited to the embodiments shown herein, but should be accorded the widest scope consistent with the present disclosure and the principles and novel features disclosed herein. Similarly, the various features described herein with respect to different implementations, embodiments, aspects, etc. of the inventive concepts disclosed herein may be combined in any suitable manner as understood by those skilled in the art and informed by the contents of this application. Thus, the individual features should be understood as "modular" and may be arranged, configured, and included in any suitable manner, unless expressly disclaimed herein or understood to be incompatible based on the knowledge available in the art as of the priority date of this application.

[0100] The embodiments described herein include one or more modes known to the inventors for carrying out the claimed subject matter. Of course, variations of those embodiments will be apparent to those skilled in the art upon reading the foregoing description. The inventors anticipate that those skilled in the art will employ such variations as appropriate, and the inventors intend for the claimed subject matter to be practiced otherwise than as specifically described herein. Accordingly, the 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 clearly contradicted by context.

Claims

1. 1. A composition of matter comprising:

1. A composition of matter comprising: a carbon fiber having a plurality of carbon fiber filaments disposed therein, at least some of the plurality of carbon fiber filaments each independently characterized by a longitudinal axis oriented at an angle that deviates substantially from parallel to a longitudinal axis of the carbon fiber.

2. 2. The composition of matter of claim 1, wherein the longitudinal axes of at least some of the plurality of carbon fiber filaments are each independently characterized by a substantially random distribution of orientation angles that deviate from parallel to the longitudinal axes of the carbon fibers.

3. 10. The composition of matter of claim 1 , wherein at least some of the carbon fiber filaments independently comprise one or more graphene platelets.

4. At least some of the one or more graphene platelets comprise three-dimensional (3D) graphene, and at least some of the carbon atoms of the 3D graphene are sp ３ 4. The composition of matter of claim 3 characterized by orbital hybridization.

5. 10. The composition of matter of claim 1, wherein at least some of the plurality of carbon fiber filaments are sized on one or more exterior surfaces of the carbon fiber.

6. a plurality of said carbon fibers aligned substantially parallel along said longitudinal axis thereof; The composition of matter of claim 1 , wherein at least some of the carbon fiber filaments crosslink some or all of the plurality of carbon fibers.

7. a plurality of said carbon fibers aligned substantially parallel along said longitudinal axis; 10. The composition of matter of claim 1, comprising: a binder matrix having a second plurality of carbon fiber filaments disposed therein, at least some of the second plurality of carbon fiber filaments crosslinking some or all of the plurality of carbon fibers.

8. 1. A composition of matter comprising:

1. A composition of matter comprising: carbon fibers having a plurality of graphene platelets disposed therein, at least some of the graphene platelets comprising three-dimensional (3D) graphene.

9. At least some of the carbon atoms of the 3D graphene are sp ３ 9. The composition of matter of claim 8 characterized by orbital hybridization.

10. The 3D graphene is a bulk of said carbon fibers; an outer surface of the carbon fiber; or The composition of matter of claim 8 comprising a plurality of ligands incorporated into both the bulk and the exterior surface of the carbon fibers.

11. 9. The composition of matter of claim 8, wherein at least some of the graphene platelets comprise one or more polycyclic aromatic hydrocarbons (PAHs) adsorbed to one or more adsorption sites on one or more surfaces of the graphene platelets.

12. 9. The composition of matter of claim 8, wherein at least some of the plurality of graphene platelets are sized on one or more exterior surfaces of the carbon fibers.

13. a plurality of said carbon fibers aligned substantially parallel along said longitudinal axis thereof; 9. The composition of matter of claim 8, wherein at least some of the graphene platelets crosslink some or all of the plurality of carbon fibers.

14. a plurality of said carbon fibers aligned substantially parallel along said longitudinal axis; 10. The composition of matter of claim 8 comprising: a binder matrix having a plurality of carbon fiber filaments disposed therein, at least some of the plurality of carbon fiber filaments crosslinking some or all of the plurality of carbon fibers.

15. 1. A composition of matter comprising: A carbon fiber having a plurality of sized carbon fiber filaments on one or more outer surfaces thereof, the carbon fiber filaments comprising: Contains graphene platelets, having the longitudinal axes of some or all of the carbon fiber filaments oriented at an angle that deviates substantially from parallel to the longitudinal axes of the carbon fibers; or the composition of matter comprising the carbon fibers, characterized in that either the carbon fibers comprise the graphene platelets and have the longitudinal axes of some or all of the carbon fiber filaments oriented at an angle that deviates substantially from parallel to the longitudinal axes of the carbon fibers.

16. 16. The composition of matter of claim 15, wherein at least some of the graphene platelets comprise one or more polycyclic aromatic hydrocarbons (PAHs) adsorbed to one or more adsorption sites on one or more surfaces of the graphene platelets.

17. 16. The composition of matter of claim 15, wherein at least some of the graphene platelets comprise three-dimensional (3D) graphene.

18. At least some of the carbon atoms of the 3D graphene are sp ３ 20. The composition of matter of claim 17 characterized by orbital hybridization.

19. The 3D graphene is a bulk of said carbon fibers; an outer surface of the carbon fiber; or 20. The composition of matter of claim 17 comprising a plurality of ligands incorporated into both the bulk and the exterior surface of the carbon fibers.

20. a plurality of said carbon fibers aligned substantially parallel along said longitudinal axis thereof; 16. The composition of matter of claim 15, wherein at least some of the carbon fiber filaments crosslink some or all of the plurality of carbon fibers.

21. a plurality of said carbon fibers aligned substantially parallel along said longitudinal axis; 16. The composition of matter of claim 15, comprising: a binder matrix having a second plurality of carbon fiber filaments disposed therein, at least some of the second plurality of carbon fiber filaments crosslinking some or all of the plurality of carbon fibers.

22. 1. A composition of matter comprising: Carbon fiber, A binder matrix, the binder matrix comprising: a plurality of carbon fiber filaments in said binder matrix; a plurality of graphene platelets in the binder matrix; or the binder matrix structurally bonded to the carbon fibers via either the plurality of carbon fiber filaments in the binder matrix or the plurality of graphene platelets in the binder matrix.

23. 23. The composition of matter of claim 22, wherein the carbon fiber comprises a second plurality of carbon fiber filaments disposed therein, at least some of the plurality of carbon fiber filaments each independently characterized by a longitudinal axis oriented at an angle that deviates substantially from parallel to the longitudinal axis of the carbon fiber.

24. 23. The composition of matter of claim 22, wherein said carbon fiber comprises a second plurality of carbon fiber filaments sized on one or more exterior surfaces of said carbon fiber.

25. a plurality of said carbon fibers aligned substantially parallel along said longitudinal axis thereof; 23. The composition of matter of claim 22, wherein at least some of the carbon fiber filaments crosslink some or all of the plurality of carbon fibers.

26. At least some of the graphene platelets independently comprise three-dimensional (3D) graphene, and at least some of the carbon atoms of the 3D graphene are sp ３ 23. The composition of matter of claim 22 characterized by orbital hybridization.

27. The 3D graphene is a bulk of said carbon fibers; An outer surface of the carbon fiber; the binder matrix, or 27. A composition of matter according to claim 26, comprising multiple ligands incorporated in combination thereof.

28. 23. The composition of matter of claim 22, wherein at least some of the graphene platelets comprise one or more polycyclic aromatic hydrocarbons (PAHs) adsorbed to one or more adsorption sites on one or more surfaces of the graphene platelets.

29. 23. The composition of matter of claim 22, wherein the carbon fibers comprise a second plurality of graphene platelets sized on one or more exterior surfaces of the carbon fibers.

30. a plurality of said carbon fibers aligned substantially parallel along said longitudinal axis thereof; 23. The composition of matter of claim 22, wherein at least some of the graphene platelets crosslink the plurality of carbon fibers.

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