Systems and methods for forming short fiber membranes, composite materials including thermoset materials, and other composite materials

Abstract

The present disclosure generally relates to systems and methods for composite materials, including short fiber membranes and other composite materials. In some aspects, a composite material comprising a plurality of aligned fibers is provided. The fibers can be substantially aligned and can be present in the composite material at a relatively high density. For example, the composite material can include substantially aligned carbon fibers embedded in a thermoplastic substrate. In some aspects, the composite material can be prepared in the following manner: the fibers are dispersed by neutralizing the electrostatic interactions between the fibers using, for example, an aqueous liquid containing fibers that can neutralize the electrostatic interactions that typically occur between the fibers. The liquid can be applied to a substrate, and the fibers can be aligned using techniques such as shear flow and / or magnetism. Other aspects generally relate to methods of using such composite materials, kits containing such composite materials, and the like.

Description

[0001] Related Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 62 / 872,686, entitled “Systems and Methods for Short-Fiber Films and Other Composites,” filed on July 10, 2019, and U.S. Provisional Patent Application Serial No. 62 / 938,265, entitled “Methods and Systems for Forming Composites Comprising Thermosets,” filed on November 20, 2019. Each of these U.S. Provisional Patent Applications is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure generally relates to systems and methods for composite materials, including short fiber membranes, composite materials including thermoset materials, and other composite materials. The present disclosure also generally relates to methods and systems for forming such composite materials. Background Art

[0004] Conventional carbon fiber composites are characterized by a planar assembly of long carbon fibers. In some composites, the long carbon fibers are woven into multi-axial fabrics or unidirectional tapes. The long carbon fiber assembly is then impregnated with a polymer resin to form a composite layer, which can be laminated with other composite layers to form a component. Since carbon fiber is a brittle material, large curvatures or sharp angles in the component can cause the long carbon fibers to break. Broken fibers introduce defects and weaken mechanical properties. One limitation of conventional carbon fiber composites is that the long carbon fibers are required to be continuous to avoid loss of performance.

[0005] This problem can be alleviated by making composite layers with short (<5mm) carbon fibers instead of long carbon fibers. Unlike long carbon fibers, short carbon fibers can easily slide down and form around large curvatures or sharp angles. Randomly oriented short carbon fibers can be used for parts with lower performance requirements. For parts with high mechanical property requirements, the short carbon fibers need to be highly oriented to approach the performance of long carbon fiber composites. Highly oriented short carbon fibers can also be used to greatly enhance the Z-axis mechanical properties of carbon fiber composites when they are oriented in the Z axis. In all cases, it is required that the fiber volume in the composite material is high (>45%) and the short carbon fibers are evenly dispersed. However, there is no commercially available method to produce short carbon fiber composites with a high fiber volume content while maintaining the dispersion or alignment of the short fibers. Therefore, improvement is needed. Summary of the invention

[0006] The present disclosure generally relates to systems and methods for composite materials, including short fiber membranes and other composite materials. In some cases, the subject matter of the present disclosure relates to interrelated products, alternative solutions to specific problems, and / or multiple different uses of one or more systems and / or articles.

[0007] In one aspect, the present disclosure generally relates to an article. In some embodiments, the article includes a composite material comprising a substrate and a plurality of discontinuous fibers contained within at least a portion of the substrate. In some cases, the plurality of discontinuous fibers are substantially aligned throughout the composite material for a fiber volume fraction of at least 30 vol%.

[0008] In another aspect, the present disclosure is generally directed to a method. According to one set of embodiments, the method includes applying a liquid to a substrate, wherein the liquid comprises a plurality of discontinuous fibers, to align at least some of the plurality of discontinuous fibers via shear flow, applying a magnetic field to the liquid to align at least some of the plurality of discontinuous fibers, and removing the liquid to form a fiber-containing substrate.

[0009] In another set of embodiments, the method includes applying a liquid to a substrate, wherein the liquid comprises a plurality of discontinuous fibers; applying a magnetic field to the liquid to align at least some of the plurality of discontinuous fibers, and / or applying a shear fluid to the substrate to align at least some of the plurality of discontinuous fibers by shear flow; and removing the liquid to form a fiber-containing substrate.

[0010] In another aspect, the present disclosure encompasses methods of making one or more embodiments described herein, such as short fiber membranes and other composite materials. In yet another aspect, the present disclosure encompasses methods of using one or more embodiments described herein, such as short fiber membranes and other composite materials.

[0011] The present disclosure also relates generally to composite materials, including composite materials including thermoset materials, in some embodiments, and methods and systems for forming such composite materials.

[0012] For example, one aspect generally relates to a composite material comprising a thermoset polymer and a plurality of discontinuous fibers contained within at least a portion of the composite material. In some embodiments, the plurality of discontinuous fibers are substantially aligned throughout the composite material for a fiber volume fraction of at least 20 vol%.

[0013] Another aspect is generally directed to a method. In one set of embodiments, the method includes coating at least a portion of a substrate comprising discontinuous fibers with a thermosetting polymer precursor, curing the thermosetting polymer precursor to form a thermosetting polymer, and removing at least some of the thermosetting polymer from the substrate as a polymer layer. In some embodiments, the discontinuous fibers are substantially aligned and are present in a volume fraction of at least 20 vol% of the substrate.

[0014] In another set of embodiments, the method generally involves coating at least a portion of a substrate with a slurry comprising water and discontinuous fibers, aligning at least some of the discontinuous fibers, removing water from the slurry to produce a substrate comprising substantially aligned discontinuous fibers; coating at least a portion of the substrate with a thermosetting polymer precursor; curing the thermosetting polymer precursor to form a thermosetting polymer; and removing at least some of the thermosetting polymer from the substrate as a polymer layer.

[0015] According to yet another set of embodiments, the method includes coating at least a portion of a substrate with a slurry comprising water and discontinuous fibers, aligning at least some of the discontinuous fibers, coating at least a portion of the substrate with a thermosetting polymer precursor, curing the thermosetting polymer precursor to form a thermosetting polymer, and removing at least some of the thermosetting polymer from the substrate as a polymer layer.

[0016] In another aspect, the present disclosure encompasses methods of making one or more of the embodiments described herein. In still another aspect, the present disclosure encompasses methods of using one or more of the embodiments described herein.

[0017] Other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments of the disclosure when considered in conjunction with the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Non-limiting embodiments of the present disclosure will be described by way of example with reference to the accompanying drawings, which are schematic and are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown is typically represented by a numeral. For purposes of clarity, not every component in every drawing is identified, nor is every component of every embodiment of the disclosure shown, where it is not necessary to illustrate the disclosure in order for one of ordinary skill in the art to understand the disclosure. In the drawings:

[0019] Figure 1 shows a substrate having aligned carbon fibers according to one embodiment of the present disclosure;

[0020] Figure 2 A composite material having aligned carbon fibers in another embodiment of the present disclosure is shown; and

[0021] Figure 3 Shown is a SEM of a composite material according to one embodiment. DETAILED DESCRIPTION

[0022] The present disclosure generally relates to systems and methods for composite materials, including short fiber membranes and other composite materials. In some aspects, a composite material comprising a plurality of aligned fibers is provided. The fibers can be substantially aligned and can be present in the composite material at a relatively high density. For example, the composite material can include substantially aligned carbon fibers embedded in a thermoplastic substrate. In some aspects, the composite material can be prepared in the following manner: the fibers are dispersed by neutralizing the electrostatic interactions between the fibers using, for example, an aqueous liquid containing fibers that can neutralize the electrostatic interactions that typically occur between the fibers. The liquid can be applied to a substrate, and the fibers can be aligned using techniques such as shear flow and / or magnetism. Other aspects generally relate to methods of using such composite materials, kits containing such composite materials, and the like.

[0023] The present disclosure also generally relates to composite materials, including composite materials comprising thermosetting materials, and methods and systems for forming such composite materials. For example, certain aspects relate to methods of transferring aligned fibers (e.g., carbon fibers) using polymers such as thermosetting polymers (e.g., epoxy resins). In some cases, the polymer can be applied to a substrate comprising fibers and extruded and / or heated to melt or solidify at least some of the polymer. The polymer can then be removed, for example, from the substrate to produce a thermosetting material comprising aligned fibers. Techniques such as shear flow and / or magnetism can be used to align the fibers. Other aspects generally relate to methods of using such composite materials, kits comprising such composite materials, and the like.

[0024] Accordingly, certain aspects generally relate to composite materials for use in various applications. For example, for parts with high mechanical property requirements, certain embodiments generally relate to composite materials containing short fibers (e.g., less than 5 mm in length), which can include carbon fibers or other types of fibers. These fibers can be highly oriented or aligned within the composite material, which can make the composite material approach the performance of long carbon fiber composites. Highly oriented fibers can also be used to greatly enhance the Z-axis mechanical properties of the composite material when they are oriented relative to the Z-axis. In some cases, high fiber volume (>45%) and evenly dispersed fibers can be used in the composite material.

[0025] Accordingly, certain embodiments relate to systems and methods for producing fiber composites having high fiber volume content while maintaining dispersion or alignment of the fibers. For example, the fibers may be relatively short and may contain carbon materials or other materials. In some cases, the fibers may be uniformly dispersed in a polymer resin or other slurry. Short fibers may have high electrostatic interactions that promote agglomeration, and the high viscosity of the polymer resin may hinder uniform dispersion at higher fiber volumes. These processing defects may thus result in inconsistent fiber reinforcement and resin content gradients in the composite material, which may greatly reduce the performance of the composite material. Therefore, certain embodiments as discussed herein may overcome these limitations. In addition, some embodiments generally relate to aligned fibers that maintain high fiber volume content. In addition to the problems faced by dispersing short fibers, the methods of the prior art also face the following problems: such as low fiber volume fractions, insufficient alignment, or generally long fiber lengths (there is a risk of fiber breakage).

[0026] Thus, certain embodiments as discussed herein relate to systems and methods for dispersing fibers by neutralizing electrostatic interactions between fibers (e.g., using an aqueous slurry). In some cases, a slurry containing well-dispersed fibers can be metered onto a substrate such as a thermoplastic film. During metering, the alignment of the fibers can be controlled, for example, by using shear flow and / or magnetic alignment. This can be implemented, for example, in a roll-to-roll manufacturing process.

[0027] For example, in one group of embodiments, an aqueous liquid containing suitable fibers can be applied to a substrate, for example, applied as a coating. Liquid can be selected to neutralize the electrostatic interactions that typically occur between fibers, as noted above. The substrate can be, for example, a thermoplastic film, or other materials, such as those discussed herein. The fiber can include carbon fibers and / or other fibers. The fibers are then aligned, for example, by applying a magnetic field and / or shearing force, for example, by applying a suitable fluid to the liquid applied to the substrate. After alignment, final composite material can be formed, for example, by applying heat (for example, to remove liquid, for example, by evaporation) and / or pressure (for example, so that the fibers are embedded in the substrate).

[0028] What is discussed above is a non-limiting example of one embodiment that can be used to produce certain types of short fiber composite materials. However, other embodiments are also possible. Therefore, more generally, different aspects relate to different systems and methods for producing short fiber membranes and other composite materials and materials.

[0029] For example, some aspects generally relate to short fiber membranes and other composite materials. In some cases, such composite materials can include a substrate and a plurality of discontinuous or short fibers contained in or embedded in the substrate or at least a portion thereof. In some cases, the plurality of fibers are substantially aligned or oriented in the substrate.

[0030] A variety of materials can be used for the substrate. For example, in one set of embodiments, the substrate comprises a polymer, such as a thermoplastic or a thermosetting material. In some cases, the substrate consists essentially of a polymer. In some embodiments, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 97%, or at least 99% by volume of the substrate (without discontinuous fibers) can be a polymer.

[0031] The substrate may include one or more polymers, including the following polymers, and may include other polymers in addition to or in place of these polymers. Examples of polymers suitable for the substrate include, but are not limited to, polyimide (PI), polyamide-imide (PAI), polyetheretherketone (PEEK), polyetherketone (PEK), polyphenylenesulfone (PPSU), polyethersulfone (PES), polyetherimide (PEI), polysulfone (PSU), polyphenylene sulfide (PPS), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), polyamide 46 (PA46), polyamide 66 (PA66), polyamide 12 (PA12), polyamide 11 (PA11), polyamide 6 (PA6), polyamide 6.6 (PA6.6), polyamide 6.6 / 6 (PA6.6 / 6), amorphous polyamide (PA6-3-T), polyethylene terephthalate Poly(ethylene terephthalate), poly(ethylene glycol), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate),

[0032] The present disclosure also generally relates to composite materials, including composite materials comprising thermosetting materials, and methods and systems for forming such composite materials. For example, certain aspects relate to methods of transferring aligned fibers (e.g., carbon fibers) using polymers such as thermosetting polymers (e.g., epoxy resins). In some cases, the polymer can be applied to a substrate comprising fibers and extruded and / or heated to melt or solidify at least some of the polymer. The polymer can then be removed, for example, from the substrate to produce a thermosetting material comprising aligned fibers. Techniques such as shear flow and / or magnetism can be used to align the fibers. Other aspects generally relate to methods of using such composite materials, kits comprising such composite materials, and the like.

[0033] Some aspects generally relate to techniques for producing fiber composites (e.g., containing carbon fibers or other fibers) having high fiber volume content while maintaining dispersion or alignment of the fibers. Certain embodiments generally relate to dispersing the fibers in a polymer resin, such as substantially uniformly. Some fibers have relatively high electrostatic interactions that can promote agglomeration. Additionally, in some cases, some polymer resins have relatively high viscosities that may hinder consistent dispersion at higher fiber volumes. These processing defects can result in inconsistent fiber reinforcement and resin content gradients in the composite, which can greatly reduce the performance of the composite. Additionally, some embodiments generally relate to aligning the fibers while maintaining a high fiber volume content.

[0034] For example, in some embodiments, carbon fibers and / or other fibers are dispersed by neutralizing electrostatic interactions between fibers in an aqueous slurry. The slurry with dispersed fibers is metered onto a substrate, for example, as a coating. The alignment of the fibers can be controlled, for example, by using shear and / or magnetic alignment. After alignment, the fibers are impregnated with a thermosetting resin such as an epoxy resin. In some cases, this process can be implemented into a roll-to-roll manufacturing process to produce a fiber composite material having a relatively high fiber volume and relatively well-controlled fiber dispersion and alignment.

[0035] In some embodiments, the substrate can be coated with a slurry or other liquid containing discontinuous fibers. For example, the substrate can be a polymer, such as polyetherimide. The slurry can be based on water or other liquids. The discontinuous fibers can include carbon fibers and / or other natural or synthetic fibers, such as those described herein. A variety of techniques can then be used, such as exposure to a magnetic field, a liquid (e.g., for shear alignment), etc., to align the fibers. In some cases, the fibers can be exposed to magnetic particles to promote magnetic alignment, but in other cases, magnetic particles may not be used, even for magnetic alignment applications.

[0036] After alignment, some or all of the water (and / or other liquid) may be removed from the slurry, for example to produce a material comprising aligned fibers. It should be understood that, in practice, the alignment of the fibers need not be perfect, i.e., not all fibers may be perfectly parallel to one another. A variety of techniques may be used to remove at least some of the water and / or other liquid, such as heating or evaporation, physical drainage, etc.

[0037] The fibers may then be coated or otherwise exposed to a thermosetting polymer. The thermosetting polymer may include epoxy resins and / or other polymers, such as those described herein. In some cases, a film or layer of the thermosetting polymer may be contacted with the fibers, and in some cases, heat and / or pressure may be applied to improve contact. For example, in some embodiments, heat and / or pressure may be applied to melt at least some of the thermosetting polymer, such as to flow between the fibers. The thermosetting polymer may then be cured or hardened in situ, such as by cooling.

[0038] The hardened thermosetting polymer can then be removed from the substrate, for example to produce a thermosetting polymer containing at least some fibers. In some cases, the thermosetting polymer can have some or all of the fibers embedded therein, partially or completely. A variety of techniques can be used to remove the polymer from the substrate. For example, in some embodiments, some or all of the thermosetting polymer can be stripped from the substrate, for example as a single polymer layer.

[0039] What is discussed above is a non-limiting example of one embodiment of the present disclosure that can be used to produce certain types of short fiber composite materials. However, other embodiments are also possible. Therefore, more generally, different aspects relate to different systems and methods for producing short fiber membranes and other composite materials and materials.

[0040] One aspect generally relates to a composite material comprising a polymer material and a plurality of discontinuous fibers. The polymer material may comprise a thermosetting polymer. In some cases, some or all of the discontinuous fibers are partially or completely embedded in the thermosetting polymer or at least a portion thereof. In some cases, the plurality of fibers are substantially aligned or oriented within the material.

[0041] In one set of embodiments, the polymeric material comprises a thermosetting polymer. In some cases, the material consists essentially of a polymer. In certain embodiments, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 97%, or at least 99% by volume of the material (excluding discontinuous fibers) may be a polymer, such as a thermosetting polymer.

[0042] In some embodiments, thermosetting polymers can be cured substantially irreversibly from a soft solid or viscous liquid prepolymer or resin to a hardened polymer by heat and / or pressure. In some cases, a catalyst can be used to promote polymerization or cross-linking.

[0043] An example of a thermosetting polymer is an epoxy resin. In some cases, the epoxy resin can be reacted (e.g., cross-linked) with itself by catalytic homopolymerization, and / or with a wide range of co-reactants, including multifunctional amines, acids (and anhydrides), phenols, alcohols, and thiols (commonly referred to as mercaptans). These co-reactants are often referred to as hardeners or curing agents, and the cross-linking reaction is often referred to as curing.

[0044] Other examples of thermosetting polymers include, but are not limited to, polyesters, polyurethanes, bakelite, duroplasts, urea-formaldehyde, melamine, diallyl phthalate, benzoxazine, polyimide, bismaleimide, cyanate, polycyanurate, furan resin, silicone resin, thiolyte, vinyl ester, etc. Other non-limiting examples include polyethyleneimine, polyetherketoneketone, polyaryletherketone, polyetheretherketone, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, poly(methyl methacrylate), acrylonitrile butadiene styrene, polyacrylonitrile, polypropylene, polyethylene, nylon, polyvinylidene fluoride, phenolic resin, bismaleimide, cyanate, polyimide, silicone rubber, styrene butadiene rubber, or ceramic precursor monomers such as siloxane, silazane, or carbosilane. Many such thermosetting polymers and their precursors are commercially available.

[0045] In some cases, thermosetting polymers can account for a relatively large proportion of the polymer material. For example, in certain embodiments, thermosetting polymers can account for at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 7%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 97% of the mass of the material. In some cases, thermosetting polymers account for no more than 97%, no more than 95%, no more than 90%, no more than 85%, no more than 80%, no more than 70%, no more than 60%, no more than 50%, no more than 40%, no more than 30%, no more than 20%, or no more than 10% of the mass of the material. Any combination of these is also possible.

[0046] In some embodiments, the material may also include additional polymers, including the following polymers, and other polymers may be included in addition to or in place of these polymers. Examples of polymers suitable for the material include, but are not limited to, polyimide (PI), polyamide-imide (PAI), polyetheretherketone (PEEK), polyetherketone (PEK), polyphenylenesulfone (PPSU), polyethersulfone (PES), polyetherimide (PEI), polysulfone (PSU), polyphenylene sulfide (PPS), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), polyamide 46 (PA46), polyamide 66 (PA66), polyamide 12 (PA12), polyamide 11 (PA11), polyamide 6 (PA6), polyamide 6.6 (PA6.6), polyamide 6.6 / 6 (PA6.6 / 6), amorphous polyamide (PA6-3-T), polyethylene terephthalate Poly(ethylene terephthalate), poly(ethylene glycol), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate), poly(ethylene terephthalate),

[0047] Some embodiments generally relate to the composite material comprising the base material formed from continuous fiber and containing multiple discontinuous fibers.This continuous fiber generally has a length significantly longer than the cross-sectional dimension of this discontinuous fiber on average.For example, this continuous fiber can have an average length that is 10 times, 30 times, 50 times, 100 times, 300 times, 500 times or 1,000 times larger than the cross-sectional dimension of this discontinuous fiber.In certain embodiments, this continuous fiber has an average aspect ratio (for example, length and diameter or average cross-sectional dimension) of at least 3, at least 5, at least 10, at least 30, at least 50, at least 100, at least 300, at least 500, at least 1,000 etc. In addition, in some cases, this continuous fiber can have an average length of at least 5mm, at least 1cm, at least 3cm, at least 5cm or at least 10cm.In some cases, longer average length is also possible.

[0048] The continuous fibers may be woven together (e.g., bidirectional weave, multidirectional weave, quasi-isotropic weave, etc.) and / or may be non-woven (e.g., unidirectional, veil, mat, etc.). In certain embodiments, at least some of the continuous fibers are substantially parallel and / or orthogonally oriented relative to each other, although other continuous fiber configurations are possible. In certain embodiments, the continuous fibers may together define a fabric or other substrate, such as a textile, tow, filament, yarn, strand, etc. In some cases, the substrate may have one orthogonal dimension that is significantly smaller than another orthogonal dimension (i.e., the substrate may have a thickness).

[0049] The continuous fibers forming the substrate may comprise any of a variety of materials, and one type of fiber or more than one type of fiber may be present in the substrate. Non-limiting examples include carbon, basalt, silicon carbide, aramid, zirconia, nylon, boron, alumina, silica, borosilicate, mullite, cotton, or any other natural or synthetic fiber.

[0050] This continuous fiber can have any suitable mean diameter.For example, this continuous fiber can have at least 10 microns, at least 20 microns, at least 30 microns, at least 50 microns, at least 100 microns, at least 200 microns, at least 300 microns, at least 500 microns, at least 1mm, at least 2mm, at least 3mm, at least 5mm, at least 1cm, at least 2cm, at least 3cm, at least 5cm, at least 10cm etc. mean diameter.In certain embodiments, this continuous fiber can have no more than 10cm, no more than 5cm, no more than 3cm, no more than 2cm, no more than 1cm, no more than 5mm, no more than 3mm, no more than 2mm, no more than 1mm, no more than 500 microns, no more than 300 microns, no more than 200 microns, no more than 100 microns, no more than 50 microns, no more than 30 microns, no more than 20 microns, no more than 10 microns etc. mean diameter.Any combination in these is also possible.For example, this continuous fiber can have between 10 microns and 100 microns, between 50 microns and 500 microns, between 100 microns and 5mm etc. mean diameter.

[0051] The continuous fibers may also have any suitable average length. For example, the continuous fibers may have an average length of at least about 0.5 cm, at least 1 cm, at least 2 cm, at least 3 cm, at least 5 cm, at least 10 cm, etc. In certain embodiments, the continuous fibers may have an average length of no more than 10 cm, no more than 5 cm, no more than 3 cm, no more than 2 cm, no more than 1 cm, no more than 0.5 cm, etc. Any combination of these is also possible; for example, the continuous fibers may have an average length between 1 cm and 10 cm, between 10 cm and 100 cm, etc.

[0052] In some cases, the continuous fiber can account for a relatively large proportion of the composite material. For example, in certain embodiments, the continuous fiber can account for at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 7%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 97% of the mass or volume of the composite material. In some cases, the continuous fiber accounts for no more than 97%, no more than 95%, no more than 90%, no more than 85%, no more than 80%, no more than 70%, no more than 60%, no more than 50%, no more than 40%, no more than 30%, no more than 20%, or no more than 10% of the mass or volume of the composite material. Any combination of these is also possible.

[0053] In one group of embodiments, the composite material may also contain one or more discontinuous fibers. These discontinuous fibers may be present in any position of the composite material, such as contained in or embedded in the substrate or at least a portion thereof, such as a polymer (such as a thermosetting polymer). In some cases, the discontinuous fibers may be substantially aligned in the composite material, such as forming a layer in the composite material. In some cases, at least 50%, at least 70%, at least 80%, at least 90%, at least 95%, at least 97%, or at least 99% by volume of the substrate may contain discontinuous fibers. As another example, at least 50%, at least 70%, at least 80%, at least 90%, at least 95%, at least 97%, or at least 99% by volume of the polymeric material may contain discontinuous fibers.

[0054] The discontinuous fibers may be formed or include any of a variety of materials, and there may be one type or more than one type of material. For example, the discontinuous fibers may include materials such as carbon (e.g., carbon fiber), basalt, silicon carbide, silicon nitride, aramid, zirconium oxide, nylon, boron, aluminum oxide, silicon dioxide, borosilicate, mullite, nitride, boron nitride, graphite, glass, polymers (including any of those described herein), etc. The discontinuous fibers may include any natural material and / or any synthetic material, and may be magnetic and / or non-magnetic.

[0055] In some embodiments, the discontinuous fibers can be at least substantially aligned in the composite material. The method for aligning discontinuous fibers is discussed in more detail herein. Various alignments are possible, and in some cases, can be determined, for example, visually or microscopically. Therefore, in some cases, alignment can be qualitatively determined. However, it should be understood that alignment does not have to be perfect. In some cases, the alignment exhibited by at least 5%, at least 10%, at least 25%, at least 50%, at least 75%, at least 85%, at least 90%, or at least 95% of the fibers in the substrate or composite material can be within 20°, 15°, 10°, or 5° of the average alignment of multiple fibers in the sample of the substrate or composite material. In some cases, the average alignment of the fiber can be oriented to be at least 60°, at least 65°, at least 70°, at least 75°, at least 85°, or at least 87° relative to the plane of the substrate or composite material at the position. Without wishing to be bound by any theory, it is believed that the discontinuous fibers are aligned substantially orthogonally to the substrate and can play a role in strengthening the substrate or composite material. This can improve the strength of the substrate or composite material, such as when stressed in different directions. For example, the fiber in the substrate can extend in 3 dimensions along substantially orthogonal directions, thereby providing strength for the substrate or composite material, regardless of the direction of the applied force. The fiber can also limit the damage to the surface such as microcracks between layers, cracks that run through plies (through-ply). In addition, in some embodiments, the fiber can enhance other characteristics of the substrate or composite material, such as electrical characteristics and / or thermal characteristics in the composite material, as a supplement or replacement of its mechanical characteristics.

[0056] While others have suggested fiber-stuffing in matrices or composites, it is believed that higher fiber volume fractions were previously unattainable due to, for example, higher electrostatic interactions that cause the fibers to agglomerate, and / or higher polymer resin viscosities that would prevent consistent dispersion. Accordingly, certain embodiments generally relate to fiber volume fractions (e.g., fiber volume fractions of substantially aligned fibers such as those discussed herein) of at least 40% fiber volume, at least 45% fiber volume, at least 50% fiber volume, at least 55% fiber volume, at least 60% fiber volume, at least 65% fiber volume, at least 70% fiber volume, etc.

[0057] A variety of techniques can be used to align the discontinuous fibers in various embodiments, including magnetic fields, shear flows, etc., as discussed in more detail below. As a non-limiting example, magnetic particles (including those discussed herein) can be attached to fibers, and then the magnetic field can be used to manipulate the magnetic particles. For example, the magnetic field can be used to move the magnetic particles into a substrate or a composite material, and / or to align the discontinuous fibers in the substrate or the composite material. The magnetic field can be constant or time-varying (e.g., oscillating), for example, as discussed herein. For example, the applied magnetic field can have a frequency of 1 Hz to 500 Hz and an amplitude of 0.01 T to 10 T. Other examples of magnetic fields are described in more detail below.

[0058] In some cases, the discontinuous fibers can have an average length or characteristic dimension of at least 1 nm, at least 3 nm, at least 5 nm, at least 10 nm, at least 30 nm, at least 50 nm, at least 100 nm, at least 300 nm, at least 500 nm, at least 1 micron, at least 3 microns, at least 5 microns, at least 10 microns, at least 20 microns, at least 30 microns, at least 50 microns, at least 100 microns, at least 200 microns, at least 300 microns, at least 500 microns, at least 1 mm, at least 2 mm, at least 3 mm, at least 5 mm, at least 10 mm, at least 15 mm, or the like. In certain embodiments, the discontinuous fibers can have an average length or characteristic size of no more than 5 cm, no more than 3 cm, no more than 2 cm, no more than 1.5 cm, no more than 1 cm, no more than 5 mm, no more than 3 mm, no more than 2 mm, no more than 1 mm, no more than 500 microns, no more than 300 microns, no more than 200 microns, no more than 100 microns, no more than 50 microns, no more than 30 microns, no more than 20 microns, no more than 10 microns, no more than 5 microns, no more than 3 microns, no more than 1 micron, no more than 500 nm, no more than 300 nm, no more than 100 nm, no more than 50 nm, no more than 30 nm, no more than 10 nm, no more than 5 nm, etc. Any combination in these is also possible. For example, the discontinuous fibers in the composite material can have an average length between 1 mm and 5 mm.

[0059] In addition, the discontinuous fibers can also have any suitable mean diameter. For example, the discontinuous fibers can have a mean diameter of at least 10 microns, at least 20 microns, at least 30 microns, at least 50 microns, at least 100 microns, at least 200 microns, at least 300 microns, at least 500 microns, at least 1mm, at least 2mm, at least 3mm, at least 5mm, at least 1cm, at least 2cm, at least 3cm, at least 5cm, at least 10cm etc. In certain embodiments, the discontinuous fibers can have a mean diameter of no more than 10cm, no more than 5cm, no more than 3cm, no more than 2cm, no more than 1cm, no more than 5mm, no more than 3mm, no more than 2mm, no more than 1mm, no more than 500 microns, no more than 300 microns, no more than 200 microns, no more than 100 microns, no more than 50 microns, no more than 30 microns, no more than 20 microns, no more than 10 microns etc. Any combination in these is also possible. For example, the discontinuous fibers can have an average diameter between 10 and 100 microns, between 50 and 500 microns, between 100 and 5 mm, and the like.

[0060] In certain embodiments, the discontinuous fibers may have a length that is, on average, at least 10 times or at least 50 times their thickness or diameter. In some cases, the fibers within the composite may have an average aspect ratio (ratio of fiber length to diameter or thickness) of at least 3, at least 5, at least 10, at least 30, at least 50, at least 100, at least 300, at least 500, at least 1,000, at least 3,000, at least 5,000, at least 10,000, at least 30,000, at least 50,000, or at least 100,000. In some cases, the average aspect ratio may be less than 100,000, less than 50,000, less than 30,000, less than 10,000, less than 5,000, less than 3,000, less than 1,000, less than 500, less than 300, less than 100, less than 50, less than 30, less than 10, less than 5, etc. In some cases, combinations of any of these are possible; for example, the aspect ratio may be between 5 and 100,000.

[0061] In some cases, the discontinuous fibers can account for a relatively large proportion of the composite material. For example, in certain embodiments, the discontinuous fibers can account for at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 7%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 97% of the mass of the composite material or polymeric material. In some cases, the discontinuous fibers account for no more than 97%, no more than 95%, no more than 90%, no more than 85%, no more than 80%, no more than 70%, no more than 60%, no more than 50%, no more than 40%, no more than 30%, no more than 20%, or no more than 10% of the mass of the composite material or polymeric material. Any combination of these is also possible.

[0062] At least some of the discontinuous fibers may be uncoated. However, in some cases, some or all of the discontinuous fibers may be coated. The coating may be used, for example, to facilitate adsorption or bonding of particles (such as magnetic particles) to the fibers, or for other reasons.

[0063] As an example, at least some of the discontinuous fibers are coated with sizing. Some examples of sizing include, but are not limited to, polypropylene, polyurethane, polyamide, phenoxy, polyimide, epoxy, etc. These sizings can be introduced into the slurry as solutions, dispersions, emulsions, etc. As other examples, the fiber can be coated with surfactants, silane coupling agents, epoxy resins, glycerol, polyurethane, organic metal coupling agents, etc. Non-limiting examples of surfactants include oleic acid, sodium lauryl sulfate, sodium lauryl sulfate, etc. Non-limiting examples of silane coupling agents include amino, benzylamino, chloropropyl, disulfide, epoxy, epoxy / melamine, mercapto, methacrylate, tertasulfido, urea, vinyl, isocyanate, and vinylbenzylamino silane coupling agents. Non-limiting examples of organic metal coupling agents include aromatic and vinyl-based organic metal coupling agents.

[0064] As mentioned, in one set of embodiments, at least some of the discontinuous fibers may be carbon fibers. The carbon fibers may be aligned directly or indirectly in a magnetic field, for example using magnetic particles or other techniques such as those discussed herein. For example, some types of carbon fibers are diamagnetic and thus may be moved directly using an applied magnetic field. Thus, certain embodiments relate to fibers or composite materials that are substantially free of paramagnetic or ferromagnetic materials and yet can be aligned using an external magnetic field. For example, if any paramagnetic or ferromagnetic materials are present, they may account for less than 5%, less than 1%, less than 0.5%, less than 0.3%, less than 0.1%, less than 0.05%, less than 0.03%, less than 0.01%, less than 0.005%, less than 0.003%, or less than 0.001% (by mass) of the material.

[0065] A variety of carbon fibers can be commercially available, including diamagnetic carbon fibers. In some cases, carbon fibers can be produced from polymer precursors such as polyacrylonitrile (PAN), rayon, pitch, etc. In some cases, carbon fibers can be spun into filament yarns, for example, using chemical processes or mechanical processes, to initially align polymer atoms, so as to enhance the final physical properties of the finished carbon fibers. The precursor compositions and mechanical processes used during spinning filament yarns can vary. After drawing or spinning, the polymer filament yarns can be heated to remove non-carbon atoms (carbonization or pyrolysis), thereby producing final carbon fibers. In certain embodiments, such techniques can be used to produce carbon fibers with relatively high carbon content, for example, at least 90%, or other contents as described herein.

[0066] Non-limiting examples of carbon fibers include, for example, pitch-based and / or polymer-based (e.g., ex-PAN or ex-rayon) variants, including those commercially available. In some cases, these may include medium / standard modulus (greater than 200 GPa) carbon fibers, high modulus (greater than 300 GPa), or ultra-high modulus (greater than 500 GPa) carbon fibers.

[0067] In one set of embodiments, the carbon fibers have a relatively high carbon content. Without wishing to be bound by any theory, it is believed that such fibers can exhibit diamagnetic properties, so that they can be oriented using a low-energy magnetic field. Generally, diamagnetic properties are the repulsion of a material to an applied magnetic field, which is produced by an induced magnetic field whose direction is opposite to that of the applied magnetic field. A material is generally classified as diamagnetic if it lacks significant paramagnetic or ferromagnetic contributions to the overall magnetic response. In many cases, the magnetic response of diamagnetic materials is very weak and can be ignored. However, relatively high magnetic fields can induce significant physical responses in such diamagnetic materials.

[0068] Therefore, in some cases, carbon fibers exhibiting a relatively highly oriented molecular structure can exhibit anisotropic, highly diamagnetic diamagnetic properties. Such diamagnetic properties make it possible to orient the carbon fibers with a relatively weak magnetic field (such as described herein). For example, in one set of embodiments, the applied magnetic field can generate a strong induced magnetic field in the CC bonds of the carbon fibers, the direction of which is opposite to the direction of the applied magnetic field. Certain types of carbon fibers can have a high degree of CC bonds parallel to the in-fiber direction, which can produce an anisotropic diamagnetic response. Thus, such carbon fibers can withstand a magnetic torque that is neutralized when the carbon fibers are aligned completely parallel to the applied magnetic field. Accordingly, by applying a suitable magnetic field, the carbon fibers can be aligned due to such diamagnetic properties. The response can be sufficient to overcome gravity effects, viscosity effects, and / or inter-particle space effects.

[0069] For example, in certain embodiments, the carbon fibers may have a carbon content greater than 80%, greater than 90%, greater than 92%, greater than 94%, greater than 95%, greater than 96%, greater than 97%, greater than 98%, greater than 99%, or greater than 99.5% by mass. In some cases, such carbon fibers may be commercially available. For example, the carbon fibers may be produced by pyrolysis, such as by "burning" or oxidizing other components that can be removed (such as by conversion to gas), leaving carbon fibers with a relatively high carbon content. Other methods of making carbon fibers are also possible, such as discussed in detail herein.

[0070] In some cases, the carbon fibers may also exhibit substantial alignment of the C-C bonds therein. For example, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% of the carbon fibers may exhibit substantial alignment of the C-C bonds. Such alignment may be determined, for example, using wide angle X-ray diffraction (WAXD) or other techniques known to those of ordinary skill in the art.

[0071] In one set of embodiments, carbon fiber can have a relatively high modulus (tensile modulus, which is a measure of stiffness). Typically, a fiber with a higher modulus is more rigid and lighter than a fiber with a low modulus. Carbon fiber typically has a higher modulus when a force is applied parallel to the fiber, that is, the carbon fiber is anisotropic. In some embodiments, the carbon fiber can have a modulus (e.g., when a force is applied parallel to the fiber) of at least 100 GPa, at least 200 GPa, at least 300 GPa, at least 400 GPa, at least 500 GPa, at least 600 GPa, at least 700 GPa, etc. It is believed that softer carbon fiber can exhibit less alignment, that is, a carbon fiber with a low modulus can have a weak physical response or no response to a magnetic field, rather than aligning in an applied magnetic field.

[0072] In one set of embodiments, the carbon fibers can exhibit an anisotropic diamagnetic response when they are free-floating in a liquid (e.g., water, oil, a polymer resin, a polymer melt, a metal melt, an alcohol such as ethanol, or another volatile organic compound) and a magnetic field is applied. For example, in some cases, the carbon fibers can align, i.e., exhibit a diamagnetic response, when a suitable magnetic field is applied. In some cases, the magnetic field can be at least 100 mT, at least 200 mT, at least 300 mT, at least 500 mT, at least 750 mT, at least 1 T, at least 1.5 T, at least 2 T, at least 3 T, at least 4 T, at least 5 T, at least 10 T, etc. In some cases, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the carbon fibers free-floating in the liquid can exhibit alignment when a suitable magnetic field is applied.

[0073] Typically, a carbon fiber has a shape such that one orthogonal dimension (e.g., its length) is significantly greater than its other two orthogonal dimensions (e.g., its width or thickness). In some cases, the fiber can be substantially cylindrical. As mentioned, in some cases, the carbon fiber can be relatively rigid; however, the carbon fiber need not be perfectly straight (e.g., even if it is curved, its length can still be determined along the fiber itself).

[0074] In one set of embodiments, the carbon fibers may have a size (e.g., a characteristic dimension) that is substantially the same as or smaller than the thickness of the substrate or composite material. For example, at least some of the carbon fibers within a substrate or composite material may have an average length that substantially spans the thickness of the substrate or composite material. However, in other cases, the characteristic dimension of the carbon fibers may be greater than the thickness.

[0075] As mentioned, in one set of embodiments, particles such as magnetic particles may be added, for example, to align discontinuous fibers, or for other applications. These particles may be adsorbed or otherwise bonded to at least some of the discontinuous fibers. In some cases, these particles may coat some or all of the discontinuous fibers and / or continuous fibers. This may be facilitated by coatings of materials as discussed herein, although coatings are not necessarily required to facilitate adsorption of these particles.

[0076] If the particles are magnetic, the particles can comprise any of a wide variety of magnetically susceptible materials. For example, the magnetic material can comprise one or more ferromagnetic materials, such as iron, nickel, cobalt, alnico, iron oxides, nickel oxides, cobalt oxides, rare earth metal oxides, or alloys comprising two or more of these ferromagnetic materials and / or other suitable ferromagnetic materials. In some cases, the magnetic particles can have a relative magnetic permeability of at least 2, at least 5, at least 10, at least 20, at least 40, at least 100, at least 200, at least 500, at least 1,000, at least 2,000, at least 5,000, or at least 10,000.

[0077] However, it should be understood that not all particles are necessarily magnetic. In some cases, non-magnetic particles can be used, for example, as a supplement and / or replacement for magnetic particles. Non-limiting examples of non-magnetic particles include glass, polymers, metals, etc.

[0078] The particles, if present, can be spherical or non-spherical, and can have any suitable shape or size. The particles can be relatively monodisperse, or have a range of sizes. In some cases, on average, the particles can have a characteristic size of at least 10 microns, at least 20 microns, at least 30 microns, at least 50 microns, at least 100 microns, at least 200 microns, at least 300 microns, at least 500 microns, at least 1mm, at least 2mm, at least 3mm, at least 5mm, at least 1cm, at least 1.5cm, at least 2cm, at least 3cm, at least 5cm, at least 10cm, etc. The particles in the composite material can also have an average characteristic size of no more than 10cm, no more than 5cm, no more than 3cm, no more than 2cm, no more than 1.5cm, no more than 1cm, no more than 5mm, no more than 3mm, no more than 2mm, no more than 1mm, no more than 500 microns, no more than 300 microns, no more than 200 microns, no more than 100 microns, no more than 50 microns, no more than 30 microns, no more than 20 microns, no more than 10 microns, etc. Any combination in these is also possible. For example, a particle may exhibit a characteristic size between 100 microns and 1 mm, between 10 microns and 10 microns, etc. The characteristic size of a non-spherical particle may be considered to be the diameter of a perfect sphere having the same volume as the non-spherical particle.

[0079] In some embodiments, particles (including magnetic particles and / or non-magnetic particles) can account for a relatively large proportion of the composite material. For example, in certain embodiments, particles can account for at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 7%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 97% of the volume of the composite material. In some cases, the particles account for no more than 97%, no more than 95%, no more than 90%, no more than 85%, no more than 80%, no more than 70%, no more than 60%, no more than 50%, no more than 45%, no more than 40%, no more than 35%, no more than 30%, no more than 25%, no more than 20%, no more than 15%, no more than 10%, no more than 7%, no more than 5%, no more than 4%, no more than 3%, no more than 2%, or no more than 1% of the volume of the composite material. Any combination of these is also possible.

[0080] As discussed, one set of embodiments generally relates to composite materials, for example, including polymeric materials such as discussed herein. In some cases, the composite material is generally planar, and / or may contain more than one layer or substrate. However, it should be understood that the substrate, composite material, or layer within the composite material need not be a mathematically perfect planar structure (although it may be); for example, the substrate, composite material, or layer may also be deformable, curved, bent, folded, rolled, pleated, etc. As an example, the substrate, composite or layer can have an average thickness of at least about 0.1 micrometer, at least about 0.2 micrometer, at least about 0.3 micrometer, at least about 0.5 micrometer, at least about 1 micrometer, at least about 2 micrometers, at least about 3 micrometers, at least about 5 micrometers, at least about 10 micrometers, at least about 30 micrometers, at least about 50 micrometers, at least about 100 micrometers, at least about 300 micrometers, at least about 500 micrometers, at least about 1 mm, at least about 2 mm, at least about 3 mm, at least about 5 mm, at least about 1 cm, at least about 3 cm, at least about 5 cm, at least about 10 cm, at least about 30 cm, at least about 50 cm, at least about 100 cm, and the like. In some cases, the average thickness can be less than 100cm, less than 50cm, less than 30cm, less than 10cm, less than 5cm, less than 3cm, less than 1cm, less than 5mm, less than 2mm, less than 3mm, less than 1mm, less than 500 microns, less than 300 microns, less than 100 microns, less than 50 microns, less than 30 microns, less than 10 microns, less than 5 microns, less than 3 microns, less than 1 micron, less than 0.5 micron, less than 0.3 micron, or less than 0.1 micron. In some embodiments, any combination of these is also possible. For example, the average thickness can be between 0.1 micron and 5,000 microns, between 10 microns and 2,000 microns, between 50 microns and 1,000 microns, etc. From one side to the other side of the substrate, composite material or layer, the thickness can be uniform or non-uniform. Moreover, the substrate, composite material or layer can be rigid (for example, as discussed herein), or can be deformable in some cases.

[0081] In one group of embodiments, there is also a binder in the composite material or polymer material, which can be used to bond continuous fibers and discontinuous fibers, such as bonding in the composite material. For example, the binder can be conducive to keeping the discontinuous fibers in place in the composite material. However, it should be understood that the binder is optional and is not required in all cases. The binder can include, for example, thermosetting materials, thermoplastic materials and / or glass polymers (vitrimer). In certain embodiments, the binder can include thermoplastic solutions, thermoplastic pellets, thermosetting resins, volatile compounds such as volatile organic compounds, water or oil. Other non-limiting examples of binders include polyesters, vinyl esters, polyethylene imines, polyetherketone ketones, polyaryletherketones, polyetheretherketones, polyphenylene sulfides, polyethylene terephthalate, polycarbonates, poly (methyl methacrylate), acrylonitrile butadiene styrene, polyacrylonitrile, polypropylene, polyethylene, nylon, silicone rubber, polyvinylidene fluoride, styrene butadiene rubber, or ceramic precursor monomers, such as siloxanes, silazane or carbosilane. In some cases, adhesive can include covalent network polymers prepared from oligomers connected from imines and independent cross-linking agents comprising reactive moieties. Non-limiting examples of reactive moieties include epoxy, isocyanate, bismaleimide, sulfide, polyurethane, anhydride and / or polyester. Examples of glass polymers include but are not limited to epoxy resins based on diglycidyl ethers of bisphenol A, aromatic polyesters, polylactic acid (polylactide), polyhydroxyurethane, epoxidized soybean oil containing citric acid, polybutadiene, etc. In certain embodiments, adhesive can also include any one or more mixtures comprising these materials and / or other materials.

[0082] In some embodiments, the binder may comprise at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 7%, at least 10%, at least 15%, at least 20%, or at least 25% of the mass of the composite material, and / or comprise no more than 25%, no more than 20%, no more than 15%, no more than 10%, no more than 7%, no more than 5%, no more than 4%, no more than 3%, no more than 2%, or no more than 1% of the mass of the composite material.

[0083] Composite materials such as those described herein can be used in a variety of applications. As non-limiting examples, composite materials can be used in a wide range of applications, such as the reinforcement of pressure vessels, parts of wind turbines, pads for supporting heavy-duty structures, sports equipment, buildings or construction materials, laminates or packaging for electronic devices, battery components, or panels for vehicles such as automobiles, aircraft, marine vehicles or spacecraft. In some cases, composite materials can be used to eliminate or reduce stress concentration or delamination in the material, harden the material, eliminate or reduce surface wear, dissipate electrical shock, transmit electrical signals, weaken or transmit electromagnetic waves, dissipate thermal shock, eliminate or reduce thermal gradients, as parts for energy storage applications, or as components of carbon fiber or ceramic matrix.

[0084] On the other hand, it is generally related to systems and methods for making composite materials such as those described herein. In one set of embodiments, the composite material can be prepared from a liquid. The liquid can be, for example, a slurry, a solution, an emulsion, etc. The liquid can contain discontinuous fibers such as those discussed herein, and can be applied to a substrate. The fibers can then be aligned as discussed above, and the liquid can then be removed, for example to produce a fiber-containing substrate. After alignment, the final composite material can be formed, for example, by applying heat (for example to remove the liquid) and / or pressure (for example to embed the fibers in the substrate), for example, to remove the liquid and / or cure the thermosetting material. In some cases, the composite material can be shaped or hardened, for example, with an adhesive, which can be used to immobilize or fix the discontinuous agent (discontinuousagent) in the substrate or composite material or in the polymer material. In addition, in some cases, the composite material can be removed from the substrate, for example, as discussed herein. In various embodiments, the composite material can be relatively rigid or soft. For example, in one set of embodiments, the composite material can be wound into a continuous coil. In some cases, a liquid, such as a slurry, can be used. The slurry may contain discontinuous fibers and optionally magnetic particles or other ingredients, which are, for example, to be applied to a substrate.

[0085] In one set of embodiments, the liquid can neutralize the electrostatic interaction between the discontinuous fibers, for example, using an aqueous liquid to neutralize. This can be used, for example, to disperse the discontinuous fibers in a liquid with a relatively high fiber volume without agglomeration. In some cases, surfactants and / or alcohols can be introduced into the slurry to reduce the electrostatic interaction between the fibers. In some cases, high shear mixing and flow can also help reduce agglomeration / flocculation.

[0086] In certain embodiments, liquid phase can include, for example, thermoplastic material or thermosetting material, such as thermoplastic solution, thermoplastic melt, thermosetting material, volatile organic compound, water or oil.The non-limiting examples of thermosetting materials include polyethyleneimine, polyetherketoneketone, polyaryletherketone, polyetheretherketone, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, poly (methyl methacrylate), acrylonitrile butadiene styrene, polyacrylonitrile, polypropylene, polyethylene, nylon, polyvinylidene fluoride, phenolic resin, epoxy resin, bismaleimide, cyanate ester, polyimide etc.The non-limiting examples of elastomer include silicone rubber and styrene butadiene rubber etc.The non-limiting examples of thermoplastic materials include epoxy resin, polyester, vinyl ester, polycarbonate, polyamide (such as nylon, PA-6, PA-12 etc.), polyphenylene sulfide, polyetherimide, polyetheretherketone, polyetherketoneketone etc. Non-limiting examples of ceramic monomers include siloxanes, silazanes, or carbosilanes, among others. In some cases, for example, one or more of these materials may be added to help evenly disperse the discontinuous fibers in the liquid. Examples of volatile organic compounds include, but are not limited to, isopropyl alcohol, butanol, ethanol, acetone, toluene, or xylene.

[0087] Any suitable amount of discontinuous fibers can be present in slurry or other liquids. For example, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, or at least 80% of the volume of slurry can be discontinuous fibers. In some cases, no more than 85%, no more than 80%, no more than 75%, no more than 70%, no more than 65%, no more than 60%, no more than 55%, no more than 50%, no more than 45%, no more than 40%, no more than 35%, no more than 30%, no more than 25%, no more than 20%, no more than 15%, or no more than 10% can be discontinuous fibers. In some cases, any combination in these is also possible. For example, slurry or other liquids can contain discontinuous fibers between 70% and 80%, between 75% and 85%, between 50% and 90%, etc.

[0088] For example, after preparing slurry or other liquid, it can be applied or exposed to substrate.Any suitable method can be used for applying slurry or other liquid to substrate.As non-limiting example, liquid can be poured, coated, sprayed or painted on substrate, or substrate can be partially or completely immersed in liquid.Liquid can be used for wetting, coating and / or surrounding substrate.

[0089] According to one set of embodiments, a magnetic field can be applied to manipulate discontinuous fibers directly or indirectly, as discussed herein. Any suitable magnetic field can be applied. In some cases, the magnetic field is a constant magnetic field. In other cases, the magnetic field can be time-varying; for example, the magnetic field can oscillate or change periodically in amplitude and / or direction, for example to facilitate manipulation of discontinuous agents. The oscillation can be a sinusoidal oscillation or another repetitive waveform (e.g., a square wave or a sawtooth wave). The frequency can be, for example, at least 0.1 Hz, at least 0.3 Hz, at least 0.5 Hz, at least 1 Hz, at least 3 Hz, at least 5 Hz, at least 10 Hz, at least 30 Hz, at least 50 Hz, at least 100 Hz, at least 300 Hz, at least 500 Hz, etc., and / or no more than 1000 Hz, no more than 500 Hz, no more than 300 Hz, no more than 100 Hz, no more than 50 Hz, no more than 30 Hz, no more than 10 Hz, no more than 50 Hz, no more than 30 Hz, no more than 10 Hz, no more than 5 Hz, no more than 3 Hz, etc. For example, the frequency can be between 1 Hz and 500 Hz, between 10 Hz and 30 Hz, between 50 Hz and Hz, etc. Additionally, the frequency may remain substantially constant, or, in some cases, the frequency may vary.

[0090] The magnetic field, whether constant or oscillating, can have any suitable amplitude. For example, the amplitude can be at least 0.001T, at least 0.003T, at least 0.005T, at least 0.01T, at least 0.03T, at least 0.05T, at least 0.1T, at least 0.3T, at least 0.5T, at least 1T, at least 3T, at least 5T, at least 10T, etc. In some cases, the amplitude can be no more than 20T, no more than 10T, no more than 5T, no more than 3T, no more than 1T, no more than 0.5T, no more than 0.3T, no more than 0.1T, no more than 0.05T, no more than 0.03T, no more than 0.01T, no more than 0.005T, no more than 0.003T, etc. The amplitude can also fall within any combination of these values. For example, the amplitude can be between 0.01T and 10T, between 1T and 3T, between 0.5T and 1T, etc. The amplitude may be substantially constant, or in certain embodiments may vary, such as within any range of these values.

[0091] In some embodiments, the direction of the magnetic field (i.e., the direction of maximum amplitude) can vary by + / -90°, + / -85°, + / -80°, + / -75°, + / -70°, + / -65°, + / -60°, + / -55°, + / -50°, + / -45°, + / -40°, + / -35°, + / -30°, + / -25°, + / -20°, + / -15°, + / -10°, + / -5° with respect to the average direction.

[0092] A variety of different devices for generating a suitable magnetic field are commercially available and include permanent magnets or electromagnets. In some cases, an oscillating magnetic field can be generated by attaching a magnet to a rotating disk and rotating the disk at an appropriate speed or frequency. Non-limiting examples of permanent magnets include ferromagnets, alnico magnets, rare earth magnets, etc.

[0093] In one set of embodiments, shear flow can be used to align or manipulate discontinuous fibers. For example, a shear fluid can be applied to the substrate to align at least some of the multiple discontinuous agents, such as in the direction of the shear flow. Examples of shear fluids that can be used include water, or another liquid, such as oil, alcohol (such as ethanol), an organic solvent (for example, isopropanol, butanol, ethanol, acetone, toluene or xylene), etc. In certain embodiments, the shear fluid can have a viscosity of at least 1 cP. In addition, in some cases, the shear fluid can be a gas, such as air. The linear flow rate of the shear fluid can be, for example, at least 10 mm / min, at least 20 mm / min, at least 30 mm / min, at least 50 mm / min, at least 100 mm / min, at least 200 mm / min, at least 300 mm / min, etc.

[0094] For example, in one set of embodiments, the fibers may be added to a liquid, including an alcohol, solvent, or resin, to form a slurry. In some cases, such as where the slurry is used as a shear fluid, the slurry may be flowed to align the fibers. However, in other cases, the slurry may be first applied to the substrate and then a shear fluid may be used to align the fibers.

[0095] In addition, in some embodiments, mechanical vibration can be used to operate discontinuous fibers, such as as a supplement and / or replacement for magnetic manipulation and / or shear flow. For example, mechanical vibration can be used to move discontinuous fibers into or on a substrate, such as into a hole or a hole in the substrate, and / or at least to align the discontinuous agent substantially in the substrate, such as discussed herein. In one group of embodiments, mechanical vibration can be applied to move discontinuous fibers at least 1 micron, at least 2 microns, at least 3 microns, at least 5 microns, at least 10 microns, at least 20 microns, at least 30 microns, at least 50 microns, at least 100 microns, at least 200 microns, at least 300 microns, at least 500 microns, at least 1,000 microns, at least 2,000 microns, at least 3,000 microns, at least 5,000 microns, or at least 10,000 microns.

[0096] In addition, in some cases, the mechanical vibration can be time-varying; for example, the mechanical vibration can be periodically changed in amplitude and / or direction, for example to facilitate the manipulation of discontinuous fibers. The oscillation can be a sinusoidal oscillation or another repetitive waveform (e.g., a square wave or a sawtooth wave). The frequency can be, for example, at least 0.1 Hz, at least 0.3 Hz, at least 0.5 Hz, at least 1 Hz, at least 3 Hz, at least 5 Hz, at least 10 Hz, at least 30 Hz, at least 50 Hz, at least 100 Hz, at least 300 Hz, at least 500 Hz, etc., and / or no more than 1000 Hz, no more than 500 Hz, no more than 300 Hz, no more than 100 Hz, no more than 50 Hz, no more than 30 Hz, no more than 10 Hz, no more than 5 Hz, no more than 3 Hz, etc. For example, the frequency can be between 1 Hz and 500 Hz, between 10 Hz and 30 Hz, between 50 Hz and Hz, etc. In addition, the frequency can remain substantially constant, or in some cases, the frequency can vary. If applied in conjunction with an oscillating magnetic field, their frequencies can be independently the same or different.

[0097] During and / or after alignment, the discontinuous fibers in the substrate can be shaped or fixed in some embodiments, for example to hinder or limit subsequent movement of the discontinuous fibers, and in one set of embodiments, a relatively hard composite material is formed. Non-limiting examples of techniques for forming composite materials include, but are not limited to, solidifying, hardening, gelling, melting, heating, evaporating, freezing, freeze-drying, or extruding a liquid or slurry. In another set of embodiments, a material such as a thermosetting polymer can be cured to harden the composite material. The substrate can therefore be formed into a composite material of a solid, gel, etc.

[0098] In some cases, the liquid may include a relatively volatile solvent that can be removed by heating and / or evaporation (e.g., by waiting an appropriate amount of time, or, for example, allowing the solvent to evaporate in a fume hood or other ventilated area). Non-limiting examples of volatile solvents include isopropanol, butanol, ethanol, acetone, toluene, or xylene. Other examples of methods for removing solvents include applying a vacuum, freeze drying, mechanical vibration, etc.

[0099] In one set of embodiments, the substrate can be heated, for example, to dry the liquid or remove a portion of the solvent, for example, to cure and / or harden the polymer precursor. For example, the substrate can be heated to a temperature of at least about 30°C, at least about 35°C, at least about 40°C, at least about 45°C, at least about 50°C, at least about 55°C, at least about 60°C, at least about 65°C, at least about 70°C, at least about 75°C, at least about 80°C, at least about 90°C, at least about 100°C, at least about 125°C, at least about 150°C, at least about 175°C, at least about 200°C, at least about 250°C, at least about 300°C, at least about 350°C, at least about 400°C, at least about 450°C, at least about 500°C, etc. Any suitable heating method can be used, such as a thermoelectric sensor, an ohmic heater, a Peltier device, a combustion heater, etc. In some cases, the viscosity of the liquid can be reduced by heating. Heating can be performed, for example, before, simultaneously with, or after applying the magnetic field and / or mechanical vibration. In some cases, heating can be used to prevent or initiate crosslinking or curing of thermosetting prepolymers.

[0100] In one set of embodiments, pressure can be applied to the substrate, for example to partially or completely embed discontinuous fibers in the substrate, for example to form a composite material, remove liquid, and / or harden and / or cure polymer precursors to form a polymer material, such as a thermoset. In some cases, pressure can be used to also remove some liquid from the substrate. Examples include, but are not limited to, hot pressing, calendering, vacuum infusion, etc. The pressure can be, for example, at least 15 psi (gauge pressure), at least 30 psi, at least 45 psi, etc. (1 psi = 6895 Pa).

[0101] In addition, in one set of embodiments, a polymer precursor, such as a precursor of a thermosetting polymer (e.g., an epoxy resin), is applied or coated on at least a portion of the substrate. For example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or substantially all of the surface of the substrate may be coated with the precursor. In some cases, the precursor embeds at least some of the discontinuous fibers (e.g., substantially aligned discontinuous fibers as discussed herein) on the substrate. For example, enough precursor may be added to substantially embed at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or substantially all of the discontinuous fibers.

[0102] The precursor can be any precursor as described herein. For example, in one set of embodiments, the precursor is a precursor of an epoxy resin. Any suitable technique can be used to coat or otherwise expose the substrate to the precursor. For example, the precursor can be poured, coated, sprayed or painted onto the substrate, or the substrate can be partially or completely immersed in the precursor. The precursor can be used to wet, coat and / or surround the substrate. Other examples include, but are not limited to, hot pressing, calendering or vacuum impregnation.

[0103] As discussed herein, the precursor can be cured and / or hardened, for example to form a polymer, by applying one or more suitable conditions, such as heat, pressure, catalysts, etc. Those of ordinary skill in the art will know the suitable conditions for curing and / or hardening a precursor (such as a thermosetting polymer) to form a polymer. Heating and / or pressure can include any of those conditions described herein. For example, in some cases, the precursor can spontaneously harden, for example when the solvent evaporates. In certain embodiments, heat can be applied, for example, by exposing the composite material to temperatures such as those described above, so that the precursor hardens. In certain embodiments, the precursor can harden when exposed to light or a catalyst, for example, to facilitate or promote a chemical reaction or polymerization reaction to polymerize the adhesive. For example, a thermosetting polymer can solidify when exposed to a suitable temperature. In other examples, the polymer can be exposed to ultraviolet light to allow polymerization to occur.

[0104] In some embodiments, the polymer formed by the precursor constitutes at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 7%, at least 10%, at least 15%, at least 20%, or at least 25% of the mass of the composite material, and / or constitutes no more than 25%, no more than 20%, no more than 15%, no more than 10%, no more than 7%, no more than 5%, no more than 4%, no more than 3%, no more than 2%, or no more than 1% of the mass of the composite material.

[0105] In some cases, after the precursor hardens or cures to form the polymeric material, the polymeric material can be optionally removed from the substrate. The polymeric material can also contain at least some of the discontinuous fibers from the substrate, such as if the precursor is impregnated within or otherwise embedded in or surrounds at least some of the discontinuous fibers on the substrate. For example, the polymeric material can embed substantially aligned discontinuous fibers.

[0106] A variety of different techniques can be used to remove at least some of the polymer from the substrate, such as as a polymer material. For example, in some embodiments, some or all of the thermosetting polymer can be stripped from the substrate, such as as a single polymer layer. The polymer material can be removed manually or automatically, such as by using a roll-to-roll process in which the material is stripped from the substrate onto a roller.

[0107] In one group of embodiments, adhesive can also be applied, for example, before, during and / or after composite material hardens and / or at least a portion of liquid is removed. In certain embodiments, adhesive can be used for producing pre-impregnated composite ply material, for example, by wetting dry ply material. In some cases, adhesive can be liquid, and can be hardened after adhesive is applied to composite material. In some cases, adhesive penetrates at least a portion of composite material. The non-limiting examples of infiltration technology include using gravity or capillary force, forcing it to enter composite material etc. by applying pressure to adhesive. Other examples include but are not limited to hot pressing, calendering or vacuum impregnation. But, in some cases, use adhesive to coat all or only a portion of substrate, for example, not necessarily require penetration.

[0108] In some cases, adhesive can include resin. Adhesive can include thermosetting material or thermoplastic material. In certain embodiments, adhesive can include thermoplastic solution, thermoplastic melt, thermoplastic pellet, thermoplastic powder, thermoplastic film, thermosetting resin, volatile compound such as volatile organic compound, water or oil. Other non-limiting examples of adhesive include epoxy resin, polyester, vinyl ester, polyethylene imine, polyetherketoneketone, polyaryletherketone, polyetheretherketone, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, poly (methyl methacrylate), acrylonitrile butadiene styrene, polyacrylonitrile, polypropylene, polyethylene, nylon, silicone rubber, polyvinylidene fluoride, polytetrafluoroethylene, perfluoroalkoxy alkane, styrene butadiene rubber or ceramic precursor monomer, such as siloxane, silazane or carbosilane. In certain embodiments, adhesive can also include any one or more mixtures including these materials and / or other materials.

[0109] In some embodiments, the binder may comprise at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 7%, at least 10%, at least 15%, at least 20%, or at least 25% of the mass of the composite material, and / or comprise no more than 25%, no more than 20%, no more than 15%, no more than 10%, no more than 7%, no more than 5%, no more than 4%, no more than 3%, no more than 2%, or no more than 1% of the mass of the composite material.

[0110] After penetration, the adhesive can harden. In some cases, the adhesive can spontaneously harden, for example, harden when the solvent evaporates. In certain embodiments, heat can be applied to harden the adhesive, for example, by exposing the composite material to temperatures such as those described above. In certain embodiments, the adhesive can harden when exposed to light or a catalyst, for example, to facilitate or promote a chemical reaction or polymerization reaction to polymerize the adhesive. For example, a thermosetting polymer can solidify when exposed to a suitable temperature. In other examples, the polymer can be exposed to ultraviolet light to allow polymerization to occur.

[0111] In some cases, for example, in addition to these, the composite material may also contain additional layers or materials. For example, the substrate may be one of a plurality of layers within the composite material. Other layers within the composite material may include polymers, composite materials, metals, ceramics, etc. For example, a composite material may be reinforced with another composite layer to form a composite structure.

[0112] Composite materials such as those discussed herein can be used in various aspects for many applications. Composite materials such as those described herein can exhibit a variety of different features in various embodiments. For example, composite materials such as those discussed herein can be used to reduce or eliminate stress concentration, reduce or eliminate delamination, increase planar strength and / or stiffness, reduce or eliminate surface wear, dissipate electricity (e.g., in electrical shock), transmit electrical signals, attenuate electromagnetic waves, transmit electromagnetic waves, dissipate heat (e.g., in thermal shock), reduce or eliminate thermal gradients, store energy, synthesize ex-PAN carbon fibers, synthesize ceramic matrix composites (CMCs), etc.

[0113] For example, in one set of embodiments, a composite ply having at least three fiber orientation axes can be produced. The fiber structure can allow the composite ply to distribute stresses between subsequent plies and adjacent components, which can reduce or eliminate stress concentrations. This can significantly improve the strength of a laminated composite structure under dynamic loading, such as when the laminated composite structure is formed with small features or paired with materials with very different stiffnesses (e.g., metal alloys or plastics).

[0114] Another group of embodiments generally relates to composite plies having interlayer regions reinforced in a through-plane direction. Such fiber reinforcement enables the composite plies to effectively distribute stresses between adjacent layers to inhibit the formation of cracks and prevent crack propagation in the interlayer region. The directional reinforcement of the interlayer region can significantly improve the strength of the laminated composite structure under impact and cyclic loading. This concept can be useful when the laminated composite structure is formed with long pieces of composite plies, for example, where a single crack in the interlayer region between the plies could potentially weaken the structural integrity of the overall structure.

[0115] Yet another group of embodiments generally relates to composite plies reinforced in a through-plane direction, such as a unidirectional fabric in the through-plane direction. Such fiber reinforcement can reinforce target loads (e.g., point loads and high pressure loads) in the through-plane direction. Such directional reinforcement in the through-plane direction can significantly improve the strength and stiffness of a laminated composite structure under expected through-plane mechanical loads. This can be used to effectively operate composite plies with through-plane reinforcement that may be susceptible to deformation during operation in an uncured state while forming an outer shell of a laminated composite structure.

[0116] Yet another set of embodiments generally relates to composite plies having carbon fibers oriented in a through-plane direction. In some cases, this through-plane reinforcement can significantly improve the resistance of the polymer matrix to damage from mechanical wear (e.g., abrasion) and / or chemical corrosion (e.g., oxidation). This concept can be used, for example, to form surfaces that protect structures from mechanical and chemical wear.

[0117] In one set of embodiments, composite plies are provided with enhanced electrical conductivity in the through-plane direction. This can significantly improve resistance to damage caused by local heating caused by charge accumulation during rapid discharge of electrical energy (e.g., lightning). This concept is particularly useful for forming surfaces that protect structures from damage caused by discharges. In another set of embodiments, composite plies are provided with enhanced near-isotropic electrical conductivity. This can effectively conduct electrical signals. In yet another set of embodiments, composite plies are provided with enhanced isotropic electrical conductivity. Such materials can effectively attenuate incident electromagnetic waves. In yet another set of embodiments, composite plies are provided with low radio frequency interference and enhanced thermal conductivity in the through-plane direction to effectively transmit electromagnetic waves without overheating.

[0118] Another group of embodiments generally relates to composite plies with enhanced thermal conductivity in the through-plane direction for adequate structural integrity under heating. In some embodiments, this can be used to improve structural integrity under rapid temperature fluctuations. Still another group of embodiments generally relates to composite plies with thermal conductivity in the through-plane direction and low electrical conductivity. This concept can be used to efficiently move and distribute heat flux, such as in electronic devices.

[0119] Yet another set of embodiments generally relates to carbon-based composite plies having electrical conductivity in a through-plane direction. This can be useful for adsorbing ionic species from an electrolyte and efficiently distributing charge.

[0120] One group of embodiments generally relates to composite plies with carbon fiber catalysts in a through-plane direction. At an appropriate temperature, a PAN (polyacrylonitrile) matrix can be oxidized and carbonized to form a carbon matrix. Another group of embodiments generally relates to composite plies with carbon fiber or silicon carbide catalysts in a through-plane direction. At an appropriate temperature, the polymer matrix can be oxidized to form a ceramic matrix.

[0121] The following documents are incorporated herein by reference: International Patent Application Serial No. PCT / US2018 / 021975, filed on March 12, 2018, entitled “Fiber-reinforced composites, methods therefor and articles comprising the same”, published as International Patent Application Publication No. WO 2018 / 175134; U.S. Patent Application Serial No. 62 / 777,438, filed on December 10, 2018, entitled “Systems and Methods for Carbon Fiber Alignment and Fiber-Reinforced Composites”; International Patent Application Serial No. PCT / US2019 / 065142, filed on December 9, 2019, entitled “Systems and Methods for Carbon Fiber Alignment and Fiber-Reinforced Composites Composites (Systems and methods for carbon fiber alignment and fiber reinforced composites)"; U.S. Provisional Patent Application Serial No. 62 / 872,686, filed on July 10, 2019, entitled "Systems and Methods for Short-Fiber Films and Other Composites (Systems and methods for short fiber films and other composite materials)"; and U.S. Provisional Patent Application Serial No. 62 / 938,265, filed on November 20, 2019, entitled "Methods and Systems for Forming Composites Comprising Thermosets (Methods and systems for forming composites containing thermosetting materials)". In addition, the U.S. patent application entitled "Compositions and Methods for Carbon Fiber-Metal and Other Composites" filed on the same day as the present application is also incorporated herein by reference in its entirety.

[0122] The following examples are intended to illustrate certain embodiments of the present disclosure, but do not exemplify the full scope of the present disclosure.

[0123] Example 1

[0124] This example shows a slurry comprising milled carbon fibers (high modulus, 95% carbon content, 150 microns long) dispersed in water to form an aqueous slurry. This slurry is poured onto a PEI substrate (76 microns thick) and a vertical magnetic field (0.2T field strength, orthogonal to the PEI substrate) is applied. The vertical magnetic field orients the milled carbon fibers during their sedimentation. After the fibers settle and align orthogonally relative to the PEI substrate, the water is evaporated. Once the water is removed, the PEI substrate with the vertically oriented milled fibers is compacted at 1 MPa and heated to 330°C. At this temperature and pressure, the PEI melts and the milled fibers are embedded in the PEI melt. The material is then cooled to ambient temperature and the pressure is released. At the end of this process, the milled fibers retain their orientation and are embedded in the PEI substrate, such as Figure 1 Visible in.

[0125] Example 2

[0126] The short fiber composite layer produced in Example 1 was formed into a layer between two commercially available carbon fiber laminates made of continuous carbon fiber and PEI in this example. The layered material was compacted at 0.5 MPa and heated to 280°C. The PEI softened and caused the vertically oriented milled fibers of the short fiber film to ooze out together with the continuous fibers of the commercially available carbon fiber laminate. The material was then cooled to ambient temperature and the pressure was released, as shown in FIG. Figure 2 Visible in.

[0127] Example 3

[0128] This example illustrates a process for making a thermoset ZRT (z-axis reinforced tape) according to one embodiment.

[0129] In the first step, the substrate is coated with a slurry. The substrate in this example is Ultem membrane, but other substrates can also be used. The slurry contains ground fibers dispersed in water and contains trace amounts of polymer additives.

[0130] Next, the milled fibers were aligned by passing the coated substrate through a 0.3 T perpendicular magnetic field.

[0131] Next, water is removed from the slurry by evaporation, although some water is drained from the sides of the substrate. The substrate is heated to 180°C to ensure the removal of water. In addition, this high heat also "tacks up" trace amounts of polymer binder, which holds the Z-axis milled fibers in place.

[0132] Next, transfer to the epoxy film was achieved by pressing the hot melt epoxy film onto the dried milled fiber coated substrate. The hot melt epoxy film was heated to 60°C to allow the epoxy to flow. After the epoxy flowed onto the substrate, the film was cooled and peeled off the substrate to produce a ZRT with a thermoset matrix. The SEM of the film was Figure 3 Available in.

[0133] Although several embodiments of the present disclosure have been described and shown herein, a person of ordinary skill in the art will easily envision a variety of other means and / or structures for performing the functions described herein and / or obtaining the results and / or one or more advantages described herein, and such variations and / or modifications are each considered to be within the scope of the present disclosure. More generally, it will be readily understood by those skilled in the art that all parameters, dimensions, materials, and configurations described herein are intended to be exemplary, and that actual parameters, dimensions, materials, and / or configurations will depend on one or more specific applications for which the teachings of the present disclosure are to be used. Those skilled in the art will recognize that, or will be able to determine many equivalent examples of the specific embodiments of the present disclosure described herein without using excessive routine experiments. Therefore, it should be understood that the aforementioned embodiments are presented only as examples, and within the scope of the attached claims and their equivalents, the present disclosure can be practiced in a manner different from that specifically described and claimed. The present disclosure relates to each individual feature, system, product, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, products, materials, kits, and / or methods is included within the scope of the present disclosure if such features, systems, products, materials, kits, and / or methods are not inconsistent with each other.

[0134] In the event that this specification and a document incorporated by reference include conflicting and / or inconsistent disclosures, this specification shall prevail. If two or more documents incorporated by reference contain conflicting and / or inconsistent disclosures, the document with the later effective date shall prevail.

[0135] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0136] As used herein in the specification and claims, the indefinite article "a" or "an" should be understood to mean "at least one", unless explicitly stated to the contrary.

[0137] The phrase "and / or" as used herein in the specification and claims should be understood to mean "either or both" of the elements so combined, i.e., elements that exist together in some cases and separately in other cases. Multiple elements listed with "and / or" should be interpreted in the same manner, i.e., "one or more" of the elements so combined. In addition to the elements specifically indicated by the "and / or" clause, other elements may optionally be present, whether related or unrelated to those specifically indicated. Thus, as a non-limiting example, when used in conjunction with open language such as "including", reference to "A and / or B" may refer to only A (optionally including elements other than B) in one embodiment; may refer to only B (optionally including elements other than A) in another embodiment; may refer to both A and B (optionally including other elements) in yet another embodiment; etc.

[0138] As used in this specification and claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" should be understood to be inclusive, i.e., including at least one, but also including multiple elements or more than one in a list of elements, as well as optional other unlisted items. Only explicitly contrary terms such as "only one" or "exactly one" or when used in the claims, "consisting of..." will refer to the inclusion of multiple elements or exactly one element in a list of elements. In general, the term "or" as used herein should only be understood to mean an exclusive alternative (e.g., "the other of one or two") preceded by an exclusive term such as "either," "one," "only one," or "exactly one."

[0139] As used in this specification and claims, with respect to a list of one or more elements, the phrase "at least one" should be understood to mean at least one element selected from any one or more elements in the list of elements, but does not necessarily include at least one of each element specifically listed in the list of elements, and does not exclude any combination of elements in the list of elements. This definition also allows for the optional presence of elements in addition to the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or equivalently "at least one of A or B", or equivalently "at least one of A and / or B") may refer in one embodiment to at least one A, optionally including more than one A, without the presence of B (and optionally including elements other than B); in another embodiment to at least one B, optionally including more than one B, without the presence of A (and optionally including elements other than A); in yet another embodiment to at least one A, optionally including more than one A, and at least one B, optionally including more than one B (and optionally including other elements); etc.

[0140] When the word "about" is used herein with respect to a number, it should be understood that yet another embodiment of the present disclosure includes the number that is not modified by the presence of the word "about."

[0141] It should also be understood that in any method claimed herein that includes more than one step or action, the order of the steps or actions of the method is not necessarily limited to the order in which the steps or actions of the method are listed unless explicitly stated to the contrary.

[0142] In the claims and in the foregoing specification, all conjunctions such as "comprising," "including," "with," "having," "containing," "involving," "maintaining," "consisting of," and the like shall be understood to be open-ended, i.e., meaning including but not limited to. Only the conjunctions "consisting of" and "consisting essentially of" shall be closed or semi-closed conjunctions, respectively, as provided in Section 2111.03 of the United States Patent Office Manual of Patent Examining Procedures.

Claims

1. A product, comprising: A composite material comprising a substrate and a plurality of discontinuous fibers contained within at least a portion of the substrate, wherein the plurality of discontinuous fibers are substantially aligned throughout the composite material for a fiber volume fraction of at least 30 vol%, wherein the discontinuous fibers are comprised of carbon fibers having a carbon content greater than 94% and a modulus of at least 200 GPa, wherein the plurality of discontinuous fibers are aligned substantially perpendicular to the substrate, and wherein the composite material is substantially free of paramagnetic or ferromagnetic material.

2. The article of claim 1, wherein: The fiber volume fraction is at least 40 vol%.

3. The article of claim 1, wherein: The fiber volume fraction is at least 50 vol%.

4. The article of claim 1, wherein: The fiber volume fraction is at least 60 vol%.

5. The article of claim 1, wherein: The fiber volume fraction is at least 70 vol%.

6. The article of claim 1, wherein: The substrate comprises a thermoplastic material.

7. The article of claim 1, wherein: The substrate consists essentially of a thermoplastic material.

8. The article of claim 1, wherein: The substrate comprises one or more of the following: polyimide PI, polyamide-imide PAI, polyetheretherketone PEEK, polyetherketone PEK, polyphenylsulfone PPSU, polyethersulfone PES, polyetherimide PEI, polysulfone PSU, polyphenylene sulfide PPS, polyvinylidene fluoride PVDF, polytetrafluoroethylene PTFE, perfluoroalkoxy alkane PFA, polyamide 46 PA46, polyamide 66 PA66, polyamide 12 PA12, polyamide 11 PA11, polyamide 6 PA6, polyamide 6.6 PA6.6, polyamide 6.6 / 6 PA6.6 / 6, amorphous polyamide PA6-3-T, polyethylene terephthalate PET, polyphthalamide PPA, liquid crystal polymer LCP, polycarbonate PC, polybutylene terephthalate PBT, polyoxymethylene POM, polyphenylene ether PPE, polymethyl methacrylate PMMA, polypropylene PP, polyethylene PE, high-density polyethylene HDPE, acrylonitrile styrene acrylate ASA, styrene acrylonitrile SAN, acrylonitrile butadiene styrene ABS, polybenzimidazole PBI, polyvinyl chloride PVC, polyparaphenylene copolymer PPP, polyacrylonitrile, polyethylene imine, polyether ketone ether ketone ketone PEKEKK, ethylene tetrafluoroethylene ETFE, polychlorotrifluoroethylene PCTFE and / or polymethylpentene PMP.

9. The article of claim 1, wherein: The substrate comprises a plurality of continuous fibers.

10. The article of claim 1, wherein: The discontinuous fibers include carbon fibers.

11. The article of claim 1, wherein: The discontinuous fibers comprise a polymer.

12. The article of claim 1, wherein: The discontinuous fibers include one or more of basalt, silicon carbide, aramid, zirconia, nylon, boron, alumina, silica, borosilicate, and / or mullite.

13. The article of claim 1, wherein: The discontinuous fibers include natural fibers.

14. The article of claim 1, wherein: The discontinuous fibers have an average length of at least 20 microns.

15. The article of claim 1, wherein: The discontinuous fibers have an average aspect ratio of length to diameter of at least 5.

16. The article of claim 1, wherein: The discontinuous fibers are coated with a coating.

17. The article of claim 16, wherein: The coating comprises a surfactant, a silane coupling agent, an epoxy resin, glycerol, polyurethane and / or an organic metal coupling agent.

18. The article of claim 16, wherein: The discontinuous fibers are coated with a size.

19. The article of claim 1, wherein: The discontinuous fibers have an anisotropic diamagnetic response in response to a magnetic field.

20. The article of claim 1, wherein: The discontinuous fibers exhibit a physical response to a magnetic field strength of 10 T.

21. The article of claim 1, wherein: At least 50% of the plurality of discontinuous fibers are aligned.

22. The article of claim 1, wherein: At least some of the plurality of discontinuous fibers have a plurality of magnetic particles attached thereto.

23. The article of claim 1, wherein: The plurality of discontinuous fibers do not contain magnetic particles.

24. The article of claim 1, wherein: The composite material comprises at least 20% by volume of the plurality of fibers.

25. The article of claim 1, wherein: The composite material has a maximum cross-sectional thickness of less than 10 cm.

26. The article of claim 1, wherein: The composite material has a maximum cross-sectional thickness of less than 1 cm.

27. The article of claim 1, wherein: The composite material is wound into a coil.

28. The article of claim 1, wherein: The substrate is one of multiple layers within the composite material.

29. The article of claim 1, wherein: The substrate layer comprises a polymer.

30. The article of claim 1, wherein: The substrate layer comprises the material of the composite material.

31. The article of claim 1, wherein: The substrate layer comprises metal.

32. The article of claim 1, wherein: The substrate layer comprises ceramic.

33. The article of claim 1, wherein: The composite material further comprises a binder bonding the substrate and the plurality of discontinuous fibers together.

34. A method comprising: applying a liquid to a substrate, wherein the liquid comprises a plurality of discontinuous fibers, to align at least some of the plurality of discontinuous fibers by shear flow, wherein the discontinuous fibers consist of carbon fibers having a carbon content greater than 94% and a modulus of at least 200 GPa; applying a magnetic field to the liquid to align at least some of the plurality of discontinuous fibers; as well as The liquid is removed to form a fiber-containing substrate, wherein the substrate is substantially free of paramagnetic material or ferromagnetic material.

35. The method of claim 34, wherein: The liquid comprises water.

36. The method of claim 34, wherein: The liquid comprises a slurry.

37. The method of claim 34, wherein: The liquid is a solution.

38. The method of claim 34, wherein: The liquid is an emulsion.

39. The method of claim 34, wherein: The liquid comprises a polymer.

40. The method of claim 34, wherein: The liquid contains a surfactant.

41. The method of claim 34, wherein: The liquid contains a binder.

42. The method of claim 34, wherein: The liquid contains a sizing agent.

43. The method of claim 34, wherein: The substrate comprises a thermoplastic material.

44. The method of claim 34, wherein: The discontinuity agent comprises carbon fibers.

45. The method of claim 34, further comprising neutralizing electrostatic interactions between the plurality of discontinuous agents.

46. ​​The method of claim 34, wherein: The magnetic field has a minimum field strength of at least 0.01 T.

47. The method of claim 34, wherein: The magnetic field has a maximum field strength not exceeding 10 T.

48. The method of claim 34, wherein: Removing the liquid includes heating the liquid to remove at least some of the liquid.

49. The method of claim 34, further comprising applying pressure to the substrate.

50. The method of claim 49, wherein: Applying pressure to the substrate causes at least some of the plurality of discontinuities to become embedded in the substrate.

51. An article, comprising: A composite material comprising a thermosetting polymer and a plurality of discontinuous fibers contained within at least a portion of the composite material, wherein the discontinuous fibers are comprised of carbon fibers having a carbon content greater than 94% and a modulus of at least 200 GPa, wherein the plurality of discontinuous fibers are substantially aligned throughout the composite material for a fiber volume fraction of at least 20 vol%, and wherein the composite material is substantially free of paramagnetic or ferromagnetic material.

52. The article of claim 51, wherein The fiber volume fraction is at least 30 vol%.

53. The article of claim 51, wherein: The fiber volume fraction is at least 40 vol%.

54. The article of claim 51, wherein: The fiber volume fraction is at least 50 vol%.

55. The article of claim 51, wherein The fiber volume fraction is at least 60 vol%.

56. The article of claim 51, wherein: The fiber volume fraction is at least 70 vol%.

57. The article of claim 51, wherein: The thermosetting polymer comprises an epoxy resin.

58. The article of claim 51, wherein The thermosetting polymer consists essentially of epoxy resin.

59. The article of claim 51, wherein: The thermosetting polymer comprises a hot melt epoxy resin.

60. The article of claim 51, wherein: The discontinuous fibers include carbon fibers.

61. The article of claim 60, wherein: The carbon fibers have a carbon content greater than 94% and a modulus of at least 200 GPa.

62. The article of claim 51, wherein: The discontinuous fibers comprise a polymer.

63. The article of claim 51, wherein: The discontinuous fibers include one or more of basalt, silicon carbide, aramid, zirconia, nylon, boron, alumina, silica, borosilicate, and / or mullite.

64. The article of claim 51, wherein: The discontinuous fibers include natural fibers.

65. The article of claim 51, wherein: The discontinuous fibers have an average length of at least 20 microns.

66. The article of claim 51, wherein: The discontinuous fibers have an average aspect ratio of length to diameter of at least 5.

67. The article of claim 51, wherein: The discontinuous fibers are coated with a coating.

68. The article of claim 67, wherein The coating comprises a surfactant, a silane coupling agent, an epoxy resin, glycerol, polyurethane and / or an organic metal coupling agent.

69. The article of claim 51, wherein: The discontinuous fibers are coated with a size.

70. The article of claim 51, wherein: The discontinuous fibers have an anisotropic diamagnetic response in response to a magnetic field.

71. The article of claim 51, wherein: The discontinuous fibers exhibit a physical response to a magnetic field strength of 10 T.

72. The article of claim 51, wherein: At least 50% of the plurality of discontinuous fibers are aligned.

73. The article of claim 51, wherein: At least some of the plurality of discontinuous fibers have a plurality of magnetic particles attached thereto.

74. The article of claim 51, wherein: The plurality of discontinuous fibers do not contain magnetic particles.

75. The article of claim 51, wherein: The composite material has a maximum cross-sectional thickness of less than 10 cm.

76. The article of claim 51, wherein The composite material has a maximum cross-sectional thickness of less than 1 cm.

77. The article of claim 51, wherein The composite material is wound into a coil.

78. The article of claim 51, wherein The composite material comprises a plurality of layers.

79. The article of claim 78, wherein The thermosetting polymer is present in one of the plurality of layers.

80. The article of claim 78, wherein The layer of the composite material comprises a metal.

81. The article of claim 78, wherein The layers of the composite material include ceramic.

82. A method comprising: coating at least a portion of a substrate comprising discontinuous fibers with a thermosetting polymer precursor, wherein the discontinuous fibers consist of carbon fibers having a carbon content greater than 94% and a modulus of at least 200 GPa, and wherein the discontinuous fibers are substantially aligned and are present in a volume fraction of at least 20 vol% of the substrate; curing the thermosetting polymer precursor to form a thermosetting polymer; as well as At least some of the thermosetting polymer is removed from the substrate as a polymer layer, wherein the substrate is substantially free of paramagnetic material or ferromagnetic material.

83. The method of claim 82, wherein: The thermosetting polymer comprises an epoxy resin.

84. The method of claim 82, wherein: The thermosetting polymer consists essentially of epoxy resin.

85. The method of claim 82, wherein: The fiber volume fraction is at least 30 vol% of the substrate.

86. The method of claim 82, wherein: The fiber volume fraction is at least 40 vol% of the substrate.

87. The method of claim 82, wherein: The fiber volume fraction is at least 50 vol% of the substrate.

88. The method of claim 82, wherein: The fiber volume fraction is at least 60 vol% of the substrate.

89. The method of claim 82, wherein: The fiber volume fraction is at least 70 vol% of the substrate.

90. The method of claim 82, wherein: At least 50% of the discontinuous fibers exhibit an alignment that is within 20° of an average alignment of the discontinuous fibers.

91. The method of claim 82, wherein: At least 75% of the discontinuous fibers exhibit an alignment that is within 20° of an average alignment of the discontinuous fibers.

92. The method of claim 82, wherein: At least 50% of the discontinuous fibers exhibit an alignment that is within 10° of an average alignment of the discontinuous fibers.

93. The method of claim 82, wherein: The discontinuous fibers include carbon fibers.

94. The method of claim 93, wherein: The carbon fibers have a carbon content greater than 94% and a modulus of at least 200 GPa.

95. The method of claim 82, wherein: The discontinuous fibers comprise a polymer.

96. The method of claim 82, wherein: The discontinuous fibers include one or more of basalt, silicon carbide, aramid, zirconia, nylon, boron, alumina, silica, borosilicate, and / or mullite.

97. The method of claim 82, wherein: The discontinuous fibers include natural fibers.

98. The method of claim 82, wherein: The discontinuous fibers have an average length of at least 20 microns.

99. The method of claim 82, wherein: The discontinuous fibers have an average length of no more than 200 microns.

100. The method of claim 82, wherein: The discontinuous fibers have an average aspect ratio of length to diameter of at least 5.

101. The method of claim 82, wherein: At least some of the discontinuous fibers are coated with a fiber coating.

102. The method of claim 101, wherein: The fiber coating comprises a surfactant, a silane coupling agent, an epoxy resin, glycerol, polyurethane and / or an organic metal coupling agent.

103. The method of claim 82, wherein: At least some of the discontinuous fibers are coated with a size.

104. The method of claim 82, wherein: At least some of the discontinuous fibers have an anisotropic diamagnetic response in response to a magnetic field.

105. The method of claim 82, wherein: At least some of the discontinuous fibers exhibit a physical response to a magnetic field strength of 10 T.

106. The method of claim 82, wherein: At least some of the discontinuous fibers have a plurality of magnetic particles attached thereto.

107. The method of claim 82, wherein: The discontinuous fibers do not contain magnetic particles.

108. The method of claim 82, wherein: Coating includes pressing a film comprising the thermosetting polymer onto the substrate.

109. The method of claim 82, wherein: Curing includes applying heat to the thermosetting polymer to a temperature at least sufficient to melt at least a portion of the thermosetting polymer.

110. The method of claim 109, wherein: The temperature is at least 40°C.

111. The method of claim 109, wherein: The temperature is at least 50°C.

112. The method of claim 109, wherein: The temperature is at least 60°C.

113. The method of claim 109, further comprising cooling the thermosetting polymer after pressing the film onto the substrate.

114. The method of claim 113, comprising cooling the substrate to ambient temperature.

115. The method of claim 113, comprising cooling the substrate by blowing air over the substrate.

116. The method of claim 82, wherein: Curing involves applying pressure to the thermosetting polymer.

117. The method of claim 82, wherein: Curing includes applying a pressure of at least 15 psig to the thermosetting polymer.

118. The method of claim 82, wherein: Curing includes applying a pressure of at least 30 psig to the thermosetting polymer.

119. The method of claim 82, wherein: The substrate comprises a polymer.

120. The method of claim 82, wherein: The substrate comprises a thermoplastic polymer.

121. The method of claim 82, wherein: The substrate comprises a metal.

122. The method of claim 82, wherein: The substrate comprises ceramic.

123. The method of claim 82, wherein: The polymer layer has a thickness of less than 200 microns.

124. The method of claim 82, wherein: The polymer layer has at least 50% of the discontinuous fibers embedded therein.

125. The method of claim 82, wherein: The polymer layer has at least 80% of the discontinuous fibers embedded therein.

126. The method of claim 82, wherein: The polymer layer has substantially all of the discontinuous fibers embedded therein.

127. The method of claim 82, wherein: A substrate comprising substantially aligned carbon fibers is prepared by: coating at least a portion of the substrate with a slurry comprising water and the discontinuous fibers; aligning at least some of the discontinuous fibers; as well as Water is removed from the slurry to produce the substrate comprising substantially aligned carbon fibers.

128. The method of claim 127, wherein: Aligning at least some of the discontinuous fibers includes exposing the substrate to a magnetic field having a magnetic field strength of at least 0.1 T.

129. The method of claim 127, wherein: Aligning at least some of the discontinuous fibers includes applying a liquid to the substrate to align at least some of the discontinuous fibers by shear flow.

130. The method of claim 127, wherein: The slurry comprises a polymer.

131. The method of claim 127, wherein: The slurry contains volatile organic compounds.

132. The method of claim 127, wherein: Removing water from the slurry includes evaporating at least some of the water.

133. The method of claim 127, wherein: Removing water from the slurry includes draining at least some of the water from the slurry.

134. A method comprising: coating at least a portion of the substrate with a slurry comprising water and discontinuous fibers, wherein the discontinuous fibers consist of carbon fibers having a carbon content greater than 94% and a modulus of at least 200 GPa; aligning at least some of the discontinuous fibers; removing water from the slurry to produce a substrate comprising substantially aligned discontinuous fibers; coating at least a portion of the substrate with a thermosetting polymer precursor; curing the thermosetting polymer precursor to form a thermosetting polymer; as well as At least some of the thermosetting polymer is removed from the substrate as a polymer layer, wherein the substrate is substantially free of paramagnetic material or ferromagnetic material.

135. The method of claim 134, wherein: Aligning at least some of the discontinuous fibers includes aligning at least some of the discontinuous fibers at an angle of at least 60° relative to the substrate.

136. The method of claim 134, wherein: Aligning at least some of the discontinuous fibers includes aligning at least some of the discontinuous fibers at an angle of at least 80° relative to the substrate.

137. The method of claim 134, wherein: Aligning at least some of the discontinuous fibers includes exposing the substrate to a magnetic field having a magnetic field strength of at least 0.1 T.

138. The method of claim 137, wherein: The magnetic field strength is at least 0.3 T.

139. The method of claim 137, wherein: The magnetic field strength is at least sufficient to align at least some of the discontinuous fibers.

140. The method of claim 137, wherein: The magnetic field is positioned to at least partially align the discontinuous fibers.

141. The method of claim 137, wherein: The magnetic field is positioned substantially orthogonal to the substrate.

142. The method of claim 137, wherein: The magnetic field is positioned at an angle of at least 60° relative to the substrate.

143. The method of claim 134, wherein: Aligning at least some of the discontinuous fibers includes applying a liquid to the substrate to align at least some of the carbon fibers by shear flow.

144. The method of claim 143, wherein: The liquid comprises water.

145. The method of claim 143, wherein: The liquid is a solution.

146. The method of claim 143, wherein: The liquid is an emulsion.

147. The method of claim 143, wherein: The liquid comprises a polymer.

148. The method of claim 143, wherein: The liquid contains a surfactant.

149. The method of claim 143, wherein: The liquid contains a sizing agent.

150. The method of claim 143, wherein: The slurry comprises a polymer.

151. The method of claim 134, wherein: The slurry contains volatile organic compounds.

152. The method of claim 134, wherein: The slurry contains at least 10 vol% discontinuous fibers.

153. The method of claim 134, wherein: The slurry contains at least 30 vol% discontinuous fibers.

154. The method of claim 134, wherein: Removing water from the slurry includes evaporating at least some of the water.

155. The method of claim 134, wherein: Removing water from the slurry includes draining at least some of the water from the slurry.

156. The method of claim 134, wherein: Removing the water includes applying heat to the slurry.

157. The method of claim 134, wherein: Removing water includes heating the slurry to a temperature of at least 100°C.

158. The method of claim 134, wherein: Removing water includes heating the slurry to a temperature of at least 150°C.

159. A method comprising: coating at least a portion of the substrate with a slurry comprising water and discontinuous fibers, wherein the discontinuous fibers consist of carbon fibers having a carbon content greater than 94% and a modulus of at least 200 GPa; aligning at least some of the discontinuous fibers; coating at least a portion of the substrate with a thermosetting polymer precursor; curing the thermosetting polymer precursor to form a thermosetting polymer; as well as At least some of the thermosetting polymer is removed from the substrate as a polymer layer, wherein the substrate is substantially free of paramagnetic material or ferromagnetic material.

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