Carbon fiber gauze, preparation method thereof and carbon fiber reinforced composite material

Abstract

The invention provides a carbon fiber gauze, a preparation method thereof and a carbon fiber reinforced composite material. The carbon fiber gauze comprises short carbon fibers and carbon nanotubes, wherein the carbon nanotubes are bonded to the short carbon fibers through a polymer adhesive; and the mass percent of the carbon nanotubes in the carbon fiber gauze is 1.8-18.6%. According to the carbon fiber gauze, chopped carbon fibers and carbon nanotubes are organically combined, and a unique multi-scale hierarchical toughening structure is constructed. When the carbon fiber gauze is used in a carbon fiber composite material, the chopped carbon fibers play a role in bridging and deflecting cracks among layers, so that the propagation of microcracks can be effectively inhibited. And the carbon nano tube absorbs energy in a resin-rich area at the crack tip of the carbon fiber composite material through mechanisms such as pulling out and breaking, so as to inhibit the generation of nano-scale cracks. In addition, the carbon nanotubes are adhered to the short carbon fibers through the polymer adhesive, so that the carbon nanotubes can be firmly fixed on the short carbon fibers, and the functional stability of the carbon fiber gauze or the carbon fiber composite material is ensured.

Description

Technical Field

[0001] This disclosure relates to the field of composite materials technology, and in particular to a carbon fiber mesh and its preparation method, and carbon fiber reinforced composite materials. Background Technology

[0002] Carbon fiber-reinforced polymer (CFRP) composites, due to their superior specific strength and specific stiffness, have been widely used in high-performance fields such as aerospace main load-bearing structures, wind turbine blades, and electric vehicle battery casings. However, the inherent weakness of laminated composites lies in their interlaminar properties, making them highly susceptible to delamination failure. Delamination can originate from manufacturing defects, external impacts, or stress concentrations. Once it occurs and propagates, it will severely weaken the overall load-bearing capacity and safety of the structure, representing a key technical bottleneck limiting its wider application. Summary of the Invention

[0003] To address the problems existing in related technologies, this disclosure provides a carbon fiber mesh and its preparation method, as well as a carbon fiber reinforced composite material.

[0004] According to a first aspect of the present disclosure, a carbon fiber mesh is provided, the carbon fiber mesh comprising chopped carbon fibers and carbon nanotubes, wherein the carbon nanotubes are bonded to the chopped carbon fibers by a polymer adhesive. The carbon nanotubes account for 1.8 to 18.6% of the mass of the carbon fiber mesh.

[0005] In some embodiments of this disclosure, the polymeric adhesive includes at least one of polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, or amphiphilic block copolymers.

[0006] In some embodiments of this disclosure, the polymeric adhesive comprises polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone; wherein the mass ratio of polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone is (1.5~2.5):(0.8~1.8):(3.1~4.0).

[0007] In some embodiments of this disclosure, the length of the chopped carbon fiber is 0.5 to 30 mm, and the surface of the chopped carbon fiber includes oxygen-containing functional groups and / or nitrogen-containing functional groups. In some embodiments of this disclosure, the areal density of the carbon fiber mesh is 15~56 g / m². 2 . According to a second aspect of the present disclosure, a method for preparing carbon fiber mesh is provided, the method being used to prepare carbon fiber mesh as described above; the method includes: Short-cut carbon fibers, carbon nanotubes, and polymeric binders are dispersed in a solvent to form a dispersion. The dispersion is dehydrated using a wet web-forming process to form a dehydrated mesh. The dehydrated mesh is dried to obtain the carbon fiber mesh.

[0008] In some embodiments of this disclosure, the concentration of the polymeric adhesive in the dispersion is 1.5~10 wt%; The polymeric adhesive comprises polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone; wherein the mass ratio of polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone is (1.5~2.5):(0.8~1.8):(3.1~4.0).

[0009] In some embodiments of this disclosure, the preparation method further includes: The chopped carbon fibers are subjected to plasma treatment with an oxygen-containing source to introduce oxygen-containing functional groups onto the surface of the chopped carbon fibers; and / or, The chopped carbon fibers are subjected to plasma treatment with a nitrogen-containing gas source to introduce nitrogen-containing functional groups on the surface of the chopped carbon fibers.

[0010] According to a third aspect of the present disclosure, a carbon fiber reinforced composite material is provided, the carbon fiber reinforced composite material comprising carbon fiber mesh as described above or carbon fiber mesh prepared by the carbon fiber mesh preparation method described above.

[0011] The beneficial effects of this disclosure include, but are not limited to: the carbon fiber mesh provided by this disclosure organically combines chopped carbon fibers with carbon nanotubes to construct a unique "multi-scale hierarchical" toughening structure. When this carbon fiber mesh is used in carbon fiber composites, the chopped carbon fibers act as crack bridging and deflection between layers, effectively inhibiting the propagation of microcracks when the carbon fiber composite is subjected to impact damage. Meanwhile, the carbon nanotubes absorb energy in the resin-rich region at the crack tip of the carbon fiber composite through mechanisms such as pull-out and fracture, inhibiting the initiation of nanoscale cracks. Furthermore, the carbon nanotubes are bonded to the chopped carbon fibers using a polymer adhesive, ensuring that the carbon nanotubes are firmly fixed to the chopped carbon fibers, guaranteeing the stability and reproducibility of the function of the carbon fiber mesh or carbon fiber composite, and solving the problem of carbon nanotubes easily agglomerating due to van der Waals forces and easily detaching or migrating during subsequent processing.

[0012] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0013] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of these embodiments. In these drawings, similar reference numerals are used to denote similar elements. The drawings described below are some embodiments of the present disclosure, but not all embodiments. Other drawings will be readily available to those skilled in the art based on these drawings without inventive effort.

[0014] Figure 1 This is a schematic diagram of a method for preparing carbon fiber mesh, which is an exemplary embodiment of this disclosure. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this disclosure clearer, the technical solutions of this disclosure will be clearly and completely described below in conjunction with the embodiments of this disclosure. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this disclosure can be arbitrarily combined with each other.

[0016] The inherent weakness of laminated carbon fiber reinforced composites lies in their interlaminar properties, making them highly susceptible to delamination failure. Delamination can originate from manufacturing defects, external impacts, or stress concentrations. Once it occurs and spreads, it severely weakens the overall load-bearing capacity and safety of the structure, representing a key technical bottleneck limiting its wider application. Various toughening strategies have been employed in related technologies, such as matrix toughening, which involves adding rubber or thermoplastic particles to the resin matrix. While this improves toughness, it often comes at the cost of sacrificing the material's stiffness, strength, and heat resistance (glass transition temperature Tg). Thermoplastic intercalation, which involves inserting thermoplastic films or nonwoven fabrics between the layers, can effectively toughen the composite, but it typically increases the thickness and weight of the component and may exhibit poor interfacial compatibility with the thermosetting matrix resin, leading to complex process integration.

[0017] Based on this, this disclosure provides a carbon fiber mesh that organically combines chopped carbon fibers with carbon nanotubes to construct a unique "multi-scale hierarchical" toughening structure. When this carbon fiber mesh is used in carbon fiber composites, the chopped carbon fibers act as crack bridging and deflection between layers, effectively inhibiting the propagation of microcracks when the carbon fiber composite is subjected to impact damage. Meanwhile, the carbon nanotubes absorb energy in the resin-rich region at the crack tip of the carbon fiber composite through mechanisms such as pull-out and fracture, inhibiting the initiation of nanoscale cracks. Furthermore, the carbon nanotubes are bonded to the chopped carbon fibers using a polymer adhesive, ensuring that the carbon nanotubes are firmly fixed to the chopped carbon fibers, guaranteeing the stability and reproducibility of the carbon fiber mesh or carbon fiber composite function, and solving the problem of carbon nanotubes easily agglomerating due to van der Waals forces and easily detaching or migrating during subsequent processing.

[0018] An exemplary embodiment of this disclosure provides a carbon fiber mesh comprising chopped carbon fibers and carbon nanotubes, wherein the carbon nanotubes are bonded to the chopped carbon fibers by a polymer adhesive; the carbon nanotubes account for 1.8 to 18.6% of the mass of the carbon fiber mesh.

[0019] In this embodiment, chopped carbon fibers and carbon nanotubes are organically combined to construct a unique "multi-scale hierarchical" toughening structure. When this carbon fiber mesh is used in carbon fiber composites, the chopped carbon fibers act as crack bridges and deflectors between layers, effectively inhibiting the propagation of microcracks when the carbon fiber composite is subjected to impact damage. Meanwhile, carbon nanotubes absorb energy in the resin-rich region at the crack tip of the carbon fiber composite through mechanisms such as pull-out and fracture, inhibiting the initiation of nanoscale cracks. The synergistic effect of chopped carbon fibers and carbon nanotubes endows the carbon fiber composite with excellent Type I (opening) and Type II (shear) interlaminar fracture toughness. However, if the carbon nanotube content is too low, the crack inhibition effect is not significant, and the mechanical or functional properties of the carbon fiber mesh or carbon fiber composite cannot be effectively improved. Conversely, if the carbon nanotube content is too high, it may lead to agglomeration of carbon nanotubes on the chopped carbon fibers, which reduces performance and increases unnecessary costs. Therefore, in this embodiment, the mass percentage of carbon nanotubes in the carbon fiber mesh is controlled between 1.8% and 18.6% to obtain the optimal performance improvement for the carbon fiber mesh or carbon fiber composite. For example, the mass percentage of carbon nanotubes in carbon fiber mesh can be 1.8%, 3.6%, 5.4%, 8.5%, 10.6%, 13.8%, 15.7%, or 18.6%. The mass percentage of carbon nanotubes in carbon fiber mesh can also be any value between the exemplary mass percentages, such as any value between 2.6% and 15.6%.

[0020] In this embodiment, carbon nanotubes are bonded to chopped carbon fibers using a polymer adhesive, ensuring that the carbon nanotubes are firmly fixed on the chopped carbon fibers. This guarantees the stability and reproducibility of the carbon fiber mesh or carbon fiber composite material, and solves the problem that carbon nanotubes are prone to agglomeration due to van der Waals forces, and are easily detached or migrated during subsequent processing.

[0021] For example, the carbon nanotubes may be at least one of single-walled carbon nanotubes, double-walled carbon nanotubes, or multi-walled carbon nanotubes.

[0022] In one exemplary embodiment, the polymeric adhesive includes at least one of polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, or an amphiphilic block copolymer.

[0023] In this embodiment, a water-soluble or water-dispersible polymeric adhesive is selected to ensure that during the preparation of the carbon fiber mesh, the polymeric adhesive can be dispersed together with the chopped carbon fibers and carbon nanotubes in an aqueous solvent, temporarily fixing the chopped carbon fibers and carbon nanotubes, and giving the carbon fiber mesh sufficient mechanical strength after drying.

[0024] The polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, or amphiphilic block copolymer polymeric adhesives selected in this embodiment contain a large number of hydroxyl (-OH), ether bonds (-O-), carbonyl (C=O), or pyrrolidone groups on their polymer chains. These functional groups can interact strongly with the surface of chopped carbon fibers and carbon nanotubes through hydrogen bonds, van der Waals forces, etc., thereby providing strong adhesion for the chopped carbon fibers and carbon nanotubes. In addition, these polymeric adhesives have good compatibility with most resin matrices. When the carbon fiber mesh provided in this embodiment is used to prepare carbon fiber composite materials, these polymeric adhesives can promote the interfacial bonding between the chopped carbon fibers and the matrix resin during the preparation process of the carbon fiber composite materials.

[0025] In an exemplary embodiment, the polymeric adhesive includes polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone; wherein the mass ratio of polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone is (1.5~2.5):(0.8~1.8):(3.1~4.0).

[0026] Polyvinyl alcohol (PVA) is primarily used as a film-forming binder for carbon fiber mesh. During the preparation of the carbon fiber mesh, PVA molecular chains adsorb onto the surface of larger chopped carbon fibers. Through steric hindrance, this effectively prevents the mechanical entanglement of the chopped carbon fibers under water flow agitation, ensuring the uniformity of the carbon fiber skeleton during subsequent mesh formation. Polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) work synergistically to efficiently and stably disperse nanoscale carbon nanotubes. Due to the large specific surface area and strong van der Waals attraction of carbon nanotubes, they are prone to aggregation in aqueous phases. As nonionic polymeric dispersants, PEO and PPV have molecular chains that adsorb onto the surface of carbon nanotubes and form a steric repulsion layer through hydrophilic segments extending into the aqueous phase. This overcomes van der Waals forces, dissociating the carbon nanotube bundles into smaller bundles or individual tubes and preventing their re-aggregation. The combined use of polyvinyl alcohol (PVA), polyethylene oxide (PEO), and polyvinylpyrrolidone (PVP) produces a synergistic effect greater than the sum of its parts (1+1+1>3). These components target and stabilize chopped carbon fibers and carbon nanotubes, avoiding the limitations of single dispersants. Furthermore, during the preparation of carbon fiber mesh, the combination of PVA, PEO, and PVP can adjust the rheological properties of the dispersion, resulting in moderate viscosity and good flowability, making it suitable for subsequent high-speed, continuous wet web-forming processes. Maintaining a mass ratio of PVA, PEO, and PVP of (1.5~2.5):(0.8~1.8):(3.1~4.0) ensures excellent dispersion of both chopped carbon fibers and carbon nanotubes, meets the process requirements for dispersion flowability, and guarantees sufficient mechanical strength in the final carbon fiber mesh. For example, the mass ratio of polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone can be 1.5:0.8:3.1, 1.5:1.8:4.0, 2.0:1.0:3.5, 2.5:1.8:4.0, or 1.8:1.5:3.8. The mass ratio of polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone can also be any value between the exemplary mass ratios, such as any value between (1.8~2.2):(1.0~1.5):(3.3~3.8).

[0027] In one exemplary embodiment, the length of the chopped carbon fiber is 0.5 to 30 mm, and the surface of the chopped carbon fiber includes oxygen-containing functional groups and / or nitrogen-containing functional groups. For example, polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, or regenerated cellulose-based carbon fiber can be selected. For example, carbon fibers of different grades such as T300, T700, T800, and IM7 can be selected.

[0028] The length of chopped carbon fibers is crucial for ensuring the formation process and performance of carbon fiber mesh. If the chopped carbon fibers are too short, they cannot form an effective carbon fiber network, resulting in low strength of the mesh. Conversely, if the chopped carbon fibers are too long, they are prone to entanglement in the dispersion during mesh preparation, making it difficult to form a uniform mesh. In this embodiment, controlling the length of the chopped carbon fibers between 0.5 and 30 mm balances the "processability" during mesh preparation with the "network structure integrity" of the finished mesh. For example, the length of the chopped carbon fibers can be 0.5 mm, 2.5 mm, 5.0 mm, 8.7 mm, 10.0 mm, 15.3 mm, 20.0 mm, 25.6 mm, or 30 mm. The length can also be any value within the exemplary range, such as 2 to 12 mm. Exemplarily, carbon fiber filaments can be mechanically processed to obtain chopped carbon fibers of the aforementioned lengths.

[0029] Short-cut carbon fibers can be plasma-treated to introduce oxygen-containing and / or nitrogen-containing functional groups onto their surface. The oxygen-containing functional groups on the surface of the short-cut carbon fibers, such as hydroxyl (-OH) and carboxyl (-COOH) groups, can improve the wettability of the carbon fiber mesh with the matrix resin through hydrogen bonding and other interactions when the carbon fiber mesh is used to prepare carbon fiber composites. The nitrogen-containing functional groups on the surface of the short-cut carbon fibers, such as amine (-NH2) groups, can undergo ring-opening reactions with the epoxy groups of the epoxy resin during the preparation of carbon fiber composites, forming strong covalent bonds. This results in the strongest interfacial bonding between the carbon fiber mesh and the matrix resin, significantly improving the interlaminar shear strength and impact resistance of the carbon fiber composites.

[0030] In one exemplary embodiment, the areal density of the carbon fiber mesh is 15~56 g / m². 2 The thickness of the carbon fiber mesh is 50~100 μm.

[0031] The areal density and thickness of carbon fiber mesh can be selected according to different application scenarios. For example, when using carbon fiber mesh as a surface layer or interlayer in lightweight products or scenarios requiring surface functionality, a lower areal density and thinner carbon fiber mesh can be selected. When a significant structural reinforcement effect is required, a higher areal density and thicker carbon fiber mesh can be selected. For example, the areal density of carbon fiber mesh can be 15 g / m². 2 20.6g / m 2 30.7g / m 2 45.1g / m 2 Or 56 g / m 2The areal density of carbon fiber mesh can also be any value between the exemplary areal densities; for example, the areal density of carbon fiber mesh can be 20.1~50.7 g / m². 2 Any value between these two values. For example, the thickness of the carbon fiber mesh can be 50 μm, 65 μm, 75 μm, 80 μm, 90 μm or 100 μm. The thickness of the carbon fiber mesh can also be any value between these exemplary thicknesses, for example, the thickness of the carbon fiber mesh can be any value between 60 and 80 μm.

[0032] An exemplary embodiment of this disclosure provides a method for preparing carbon fiber mesh, the method being used to prepare carbon fiber mesh as described above; as Figure 1 As shown, the preparation method includes: S100: Short-cut carbon fibers, carbon nanotubes, and polymer binders are dispersed in a solvent to form a dispersion.

[0033] For example, the solvent can be an aqueous solvent, such as deionized water. Short-cut carbon fibers, carbon nanotubes, and polymer binders are added to deionized water. To ensure uniform dispersion of the components, a combination of mechanical stirring (200-1500 rpm) and ultrasonic treatment can be used to promote dispersion. Ultrasonic treatment helps break up aggregates of carbon nanotubes, forming a uniform and stable dispersion.

[0034] S200: The dispersion is dehydrated by a wet web forming process to form a dehydrated mesh.

[0035] In step S100, the polymer adhesive is dispersed together with the chopped carbon fibers and carbon nanotubes in a solvent to form a dispersion. The polymer adhesive can fix the chopped carbon fibers and carbon nanotubes, so that the carbon nanotubes are locked in the carbon fiber skeleton, ensuring the stability and reproducibility of the carbon fiber mesh preparation process and function. This solves the problem that carbon nanotubes are prone to agglomeration due to van der Waals forces and are easy to fall off or migrate in the wet web forming process.

[0036] In step S200, for example, a uniform dispersion can be pumped into a wet web-forming device, where it is dehydrated on a moving screen to form a wet web. By controlling the amount of chopped carbon fibers, carbon nanotubes, and polymer binders, as well as the web speed, the areal density and thickness of the web can be precisely controlled to form a dehydrated web. When the stable and homogeneous dispersion is dehydrated on the screen, the carbon nanotubes are "solidified" into the dehydrated web structure, the larger chopped carbon fibers form a porous framework, and the stably dispersed carbon nanotubes, together with the polymer binder, are physically retained and uniformly deposited at the nodes of the framework and on the surface of the chopped carbon fibers, ultimately forming a three-dimensional interpenetrating network structure that runs through the entire structure.

[0037] S300: Dry the dehydrated mesh to obtain carbon fiber mesh.

[0038] The dehydrated mesh is dried in a hot air or vacuum oven at 80~120℃ to obtain the final flexible carbon fiber mesh.

[0039] This embodiment employs a wet web-forming process to prepare carbon fiber mesh. This process boasts high production efficiency, controllable costs, and ease of large-scale industrial production. The resulting carbon fiber mesh exhibits stable morphology and is easy to handle, allowing integration into various carbon fiber composite material preparation processes such as prepreg layup, autoclave curing, or resin transfer molding. Furthermore, the wet web-forming process enables the simultaneous deposition and self-assembly of chopped carbon fibers, carbon nanotubes, and polymeric adhesives at the microscale, forming a three-dimensional network structure where all components are homogeneously distributed and physically interpenetrating throughout the thickness of the carbon fiber mesh. This fundamentally differs from the two-dimensional laminated structure formed by spraying methods, where functional components are only concentrated on the surface. This unique three-dimensional network structure maximizes effective bonding at the nodes of chopped carbon fibers, providing a structural basis for efficient multi-scale load transfer in carbon fiber mesh or carbon fiber composites. It also endows carbon fiber composites with good damage tolerance, meeting the demands of high-end applications, such as safety-critical applications like aerospace main load-bearing structures.

[0040] In an exemplary embodiment, the concentration of the polymeric adhesive in the dispersion is 1.5~10wt%. The polymeric adhesive includes polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone; wherein the mass ratio of polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone is (1.5~2.5):(0.8~1.8):(3.1~4.0).

[0041] The concentration of the polymeric adhesive in the dispersion is crucial for ensuring the strong bond between chopped carbon fibers and carbon nanotubes. When the concentration of the polymeric adhesive in the dispersion is too low, the adhesive force on the chopped carbon fibers and carbon nanotubes is insufficient, resulting in weak fixation of the carbon nanotubes to the chopped carbon fibers and poor strength of the resulting carbon fiber mesh. When the concentration of the polymeric adhesive in the dispersion is too high, the dispersion becomes viscous and has poor flowability, making uniform wet web formation impossible, and the dried carbon fiber mesh is too stiff and brittle. Therefore, in this embodiment, the concentration of the polymeric adhesive in the dispersion is controlled between 1.5 and 10 wt% to ensure that the dispersion has a suitable viscosity for molding, while also forming a high-strength carbon fiber mesh after drying. For example, the concentration of the polymeric adhesive in the dispersion can be 1.5 wt%, 4.3 wt%, 8.6 wt%, or 10 wt%, or any value between these exemplary concentrations, such as any value between 3.5 and 9.4 wt%.

[0042] Polyvinyl alcohol (PVA) is primarily used as a film-forming binder for carbon fiber mesh. During the preparation of carbon fiber mesh, PVA molecular chains adsorb onto the surface of larger chopped carbon fibers. Through steric hindrance, this effectively prevents the mechanical entanglement of the chopped carbon fibers under water flow agitation, ensuring the uniformity of the carbon fiber skeleton during wet web formation. Polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) work synergistically to efficiently and stably disperse nanoscale carbon nanotubes. Due to the large specific surface area and strong van der Waals attraction of carbon nanotubes, they are prone to aggregation in aqueous phases. As nonionic polymeric dispersants, PEO and PPV have molecular chains that adsorb onto the surface of carbon nanotubes and form a steric repulsion layer through hydrophilic segments extending into the aqueous phase. This overcomes van der Waals forces, dissociating the carbon nanotube bundles into smaller bundles or individual tubes and preventing their re-aggregation. The combined use of polyvinyl alcohol (PVA), polyethylene oxide (PEO), and polyvinylpyrrolidone (PVP) produces a synergistic effect greater than the sum of its parts (1+1+1>3). These components target and stabilize chopped carbon fibers and carbon nanotubes, avoiding the limitations of single dispersants. Furthermore, during the preparation of carbon fiber mesh, the combination of PVA, PEO, and PVP can adjust the rheological properties of the dispersion, resulting in moderate viscosity and good flowability, making it suitable for subsequent high-speed, continuous wet web-forming processes. Maintaining a mass ratio of PVA, PEO, and PVP of (1.5~2.5):(0.8~1.8):(3.1~4.0) ensures excellent dispersion of both chopped carbon fibers and carbon nanotubes, meets the process requirements for dispersion flowability, and guarantees sufficient mechanical strength in the final carbon fiber mesh. For example, the mass ratio of polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone can be 1.5:0.8:3.1, 1.5:1.8:4.0, 2.0:1.0:3.5, 2.5:1.8:4.0, or 1.8:1.5:3.8. The mass ratio of polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone can also be any value between the exemplary mass ratios, such as any value between (1.8~2.2):(1.0~1.5):(3.3~3.8).

[0043] In an exemplary embodiment, the method for preparing carbon fiber mesh further includes: subjecting chopped carbon fibers to plasma treatment using an oxygen-containing source to introduce oxygen-containing functional groups onto the surface of the chopped carbon fibers.

[0044] In this embodiment, plasma treatment of chopped carbon fibers using an oxygen-containing source, such as oxygen (O2), can introduce oxygen-containing polar groups such as hydroxyl (-OH) and carboxyl (-COOH) groups onto the surface of the chopped carbon fibers. This can improve the wettability of the carbon fiber mesh with the matrix resin through hydrogen bonding and other interactions when the carbon fiber mesh is used to prepare carbon fiber composite materials.

[0045] In an exemplary embodiment, the method for preparing carbon fiber mesh further includes: subjecting chopped carbon fibers to plasma treatment using a nitrogen-containing gas source to introduce nitrogen-containing functional groups onto the surface of the chopped carbon fibers.

[0046] In this embodiment, short-cut carbon fibers are subjected to plasma treatment using a nitrogen-containing gas source, such as nitrogen (N2) or ammonia (NH3). This introduces nitrogen-containing functional groups such as amine groups (-NH2) onto the surface of the short-cut carbon fibers. As a result, when the carbon fiber mesh is used to prepare carbon fiber composites, the introduced nitrogen-containing functional groups such as amine groups (-NH2) react with the epoxy groups of the epoxy resin to form strong covalent bonds. This achieves the strongest interfacial bonding between the carbon fiber mesh and the matrix resin, thereby significantly improving the interlaminar shear strength and impact resistance of the carbon fiber composites.

[0047] An exemplary embodiment of this disclosure provides a carbon fiber reinforced composite material, which includes carbon fiber mesh as described above or carbon fiber mesh prepared by the method described above.

[0048] For example, the carbon fiber mesh described above, or carbon fiber mesh prepared using the methods described above, can be used as a toughening intercalation layer, laid between layers of carbon fiber / resin prepreg. Subsequently, it is cured and molded using standard autoclave, molding, or vacuum bag processes to finally obtain a carbon fiber reinforced composite material. This carbon fiber reinforced composite material exhibits significantly improved toughness, impact resistance, and interlaminar properties, and can be widely used in high-tech fields such as aerospace, new energy vehicles, sporting goods, and electronic device housings, meeting their high standards for lightweight, high strength, and high functionality.

[0049] To more clearly explain the technical solutions provided by the exemplary embodiments of this disclosure, a specific example of the method for preparing the carbon fiber mesh provided by the exemplary embodiments of this disclosure is given.

[0050] The chopped carbon fibers were subjected to plasma treatment using an oxygen source (5W power, 100Pa pressure, 60 seconds processing time) / a nitrogen source (7.5W power, 80Pa pressure, 90 seconds processing time).

[0051] Short-cut carbon fibers, carbon nanotubes, and polymeric binders are dispersed in a solvent to form a dispersion. The dispersion is dehydrated using a wet web-forming process to form a dehydrated mesh. The dehydrated mesh is dried to obtain carbon fiber mesh.

[0052] Carbon fiber mesh was prepared in Examples 1-6 according to the preparation methods described in the specific examples above. T800 grade carbon fiber / epoxy resin unidirectional prepreg was used, and boards were fabricated according to various mechanical property testing standards. The carbon fiber mesh from Examples 1-6 was laid between the layers of carbon fiber / epoxy resin prepreg, and cured in an autoclave at 180°C for 2 hours to obtain carbon fiber reinforced composite laminates. Mechanical properties were tested according to relevant ASTM standards, including: interlaminar shear strength (ILSS, ASTM D2344), compressive strength (SACMA SRM 1), Type I interlaminar fracture toughness (GIC, ASTM D5528), Type II interlaminar fracture toughness (GIIC, ASTM D7905), and post-impact compressive strength (CAI, ASTM D7136 / D7137). See Table 1 for details. Table 1

[0053] In addition, this disclosure also uses T800 grade carbon fiber / epoxy resin unidirectional prepreg and prepares the board according to various mechanical property test standards, but does not lay carbon fiber mesh. The carbon fiber reinforced composite laminate is cured at 180°C for 2 hours using an autoclave process, as Comparative Example 1. Mechanical property tests were performed on Comparative Example 1 according to relevant ASTM standards. The interlaminar shear strength of the carbon fiber reinforced composite laminate in Comparative Example 1 is 97 MPa, the compressive strength is 1476 MPa, and the type I interlaminar fracture toughness is 408 J / m. 2 Type II interlaminar fracture toughness: 932 J / m 2 The compressive strength after impact is 237 MPa.

[0054] As can be seen from Table 1 and the data of Comparative Example 1, the mechanical properties of the carbon fiber reinforced composite laminate prepared using the carbon fiber mesh provided in the embodiments of this disclosure are significantly improved compared with Comparative Example 1 which was not toughened by carbon fiber mesh.

[0055] The above-described contents can be implemented individually or in various combinations, and all such variations are within the scope of this disclosure.

[0056] Finally, it should be noted that in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0057] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A carbon fiber mesh, characterized in that, The carbon fiber mesh includes chopped carbon fibers and carbon nanotubes, wherein the carbon nanotubes are bonded to the chopped carbon fibers by a polymer adhesive. The carbon nanotubes account for 1.8 to 18.6% of the mass of the carbon fiber mesh.

2. The carbon fiber mesh according to claim 1, characterized in that, The polymeric adhesive includes at least one of polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, or amphiphilic block copolymers.

3. The carbon fiber mesh according to claim 2, characterized in that, The polymeric adhesive comprises polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone; wherein the mass ratio of polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone is (1.5~2.5):(0.8~1.8):(3.1~4.0).

4. The carbon fiber mesh according to claim 1, characterized in that, The length of the chopped carbon fiber is 0.5~30mm, and the surface of the chopped carbon fiber includes oxygen-containing functional groups and / or nitrogen-containing functional groups.

5. The carbon fiber mesh according to claim 1, characterized in that, The areal density of the carbon fiber mesh is 15~56 g / m². 2 .

6. A method for preparing carbon fiber mesh, characterized in that, The preparation method is used to prepare carbon fiber mesh as described in any one of claims 1 to 5; the preparation method includes: Short-cut carbon fibers, carbon nanotubes, and polymeric binders are dispersed in a solvent to form a dispersion. The dispersion is dehydrated using a wet web-forming process to form a dehydrated mesh. The dehydrated mesh is dried to obtain the carbon fiber mesh.

7. The method for preparing carbon fiber mesh according to claim 6, characterized in that, The concentration of the polymeric adhesive in the dispersion is 1.5~10 wt%; The polymeric adhesive comprises polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone; wherein the mass ratio of polyvinyl alcohol, polyethylene oxide, and polyvinylpyrrolidone is (1.5~2.5):(0.8~1.8):(3.1~4.0).

8. The method for preparing carbon fiber mesh according to claim 6, characterized in that, The preparation method further includes: The chopped carbon fibers are subjected to plasma treatment with an oxygen-containing source to introduce oxygen-containing functional groups onto the surface of the chopped carbon fibers; and / or, The chopped carbon fibers are subjected to plasma treatment with a nitrogen-containing gas source to introduce nitrogen-containing functional groups on the surface of the chopped carbon fibers.

9. A carbon fiber reinforced composite material, characterized in that, The carbon fiber reinforced composite material includes carbon fiber mesh prepared by any one of the methods described in claims 1 to 5 or as described in any one of claims 6 to 8.

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