Carbon fiber and glass fiber composite modified material and preparation method thereof

Abstract

This invention discloses a carbon fiber and glass fiber composite modified material and its preparation method, belonging to the technical field of carbon fiber and glass fiber composite materials. It comprises the following components in the following mass ratio: 30%-60% reinforcing phase, with the remainder being a resin matrix. The reinforcing phase is a hybrid fiber; the hybrid fiber is composed of polydopamine-modified carbon fiber and epoxy-modified glass fiber chemically bonded together via aminated carbon nanotubes, with a carbon fiber to glass fiber mass ratio of 1-3:3-1; the mass of the aminated carbon nanotubes is 0.5%-3% of the total mass of the carbon fiber and glass fiber. The carbon fiber and glass fiber composite modified material and its preparation method of this invention construct a fully chemically bonded hybrid fiber network through carbon nanotube molecular bridges, ensuring the interfacial compatibility of the hybrid material, and fundamentally eliminating the essential defect of modulus abrupt change through a single-filament-level core-shell gradient structure.

Description

Technical Field

[0001] This invention specifically relates to a carbon fiber and glass fiber composite modified material and its preparation method, belonging to the technical field of carbon fiber and glass fiber composite materials. Background Technology

[0002] Carbon fiber is lightweight and high-strength, but it also suffers from high cost, low elongation at break, and susceptibility to damage upon impact. While glass fiber (GFB) has relatively lower tensile strength and elastic modulus, its low cost, high elongation, and good vibration and impact energy absorption properties make it a good choice to hybridize carbon and glass fibers, balancing cost and performance. However, the modulus mismatch between carbon and glass fibers causes stress concentration at the macroscopic interface of the heterogeneous materials, leading to brittle and catastrophic delamination. To address this, Chinese Patent Publication No. CN121224162A discloses an interlayer toughened carbon-glass hybrid composite material and its preparation method. This method introduces a fiber mesh layer between the macroscopic heterogeneous layup interface of carbon and glass fibers. This structure, by forming a modulus gradient transition zone, transforms the material's failure mode from brittle delamination to ductile failure, significantly enhancing the material's damage tolerance and reliability. However, the above structure still has the following technical problems: 1. Poor interfacial compatibility and low stress transfer efficiency: Existing technologies mostly adopt interlayer or intralayer physical mixing methods. The surface properties of carbon fiber and glass fiber are very different, and there is no chemical bond between them. When subjected to load, stress concentration is easily generated at the contact interface, which induces microcrack propagation, resulting in interface debonding and interlayer cracking, leading to a significant decrease in the mechanical properties of composite materials. 2. The inherent defect of modulus mismatch cannot be eliminated: The elastic modulus difference between carbon fiber and glass fiber is 3-5 times. Traditional physical mixing cannot solve the problem of incoordination in deformation of the two fibers. Even if the interfacial bonding force between the fiber and the resin is improved, the inherent defect of stress concentration caused by the sudden change in modulus cannot be eliminated.

[0003] 3. The interfacial bonding strength, interlaminar properties, and fatigue resistance between the fibers cannot meet the application requirements. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a carbon fiber and glass fiber composite modified material and its preparation method. By constructing a fully chemically bonded hybrid fiber network through carbon nanotube molecular bridges, the interfacial compatibility of the hybrid material is ensured. Furthermore, through a single-filament-level core-shell gradient structure, the essential defect of modulus abrupt change is fundamentally eliminated.

[0005] The carbon fiber and glass fiber composite modified material of the present invention comprises the following components in the following mass ratio: 30%-60% reinforcing phase, with the remainder being a resin matrix, wherein the reinforcing phase is a hybrid fiber; the hybrid fiber is formed by chemically bonding polydopamine-modified carbon fiber and epoxy-modified glass fiber through aminated carbon nanotubes, and the mass ratio of carbon fiber to glass fiber is 1~3:3~1; the mass of the aminated carbon nanotubes is 0.5%-3% of the total mass of carbon fiber and glass fiber; the role of the aminated carbon nanotubes here is to achieve the integration of carbon fiber and glass fiber into a heterogeneous fiber structure through the carbon nanotubes. Sub-bridges address the interfacial bonding problem between two completely different fibers; in the core-shell scheme, the outer surface of all fibers is a glass fiber shell with epoxy groups. The amino groups at both ends of the aminated carbon nanotubes can covalently bond with the epoxy groups on the surfaces of two adjacent core-shell fibers, which is equivalent to achieving molecular-level "welding" of adjacent fibers through carbon nanotubes. This completely replaces the weak interface of traditional composite materials that relies solely on physical bonding with resin, constructing a three-dimensional continuous chemical bonding network that runs through the entire material. This solves the macroscopic interface debonding problem between fibers, bundles, and layers.

[0006] Further, the resin matrix comprises the following components in parts by weight: 100 parts epoxy resin, 25-35 parts phosphorus-nitrogen modified aromatic amine curing agent, 5-10 parts terminal epoxy butadiene-acrylonitrile rubber, and 0.5-1 parts accelerator.

[0007] Furthermore, the hybrid fiber has a coaxial core-shell gradient structure, and the hybrid fiber consists of a carbon fiber core layer, a SiC nanowire intermediate layer, and a glass fiber shell layer from the inside out; the carbon fiber core layer is polydopamine-modified carbon fiber, and the glass fiber shell layer is epoxy-modified glass fiber.

[0008] The role of aminated carbon nanotubes here is as follows: Since the outer surface of the glass fiber shell is covered with epoxy groups, and the amino groups at both ends of the aminated carbon nanotubes can covalently bond with the epoxy groups on the surfaces of two adjacent fibers, the adjacent fibers are "welded" at the molecular level through the carbon nanotubes. This completely replaces the weak interface in traditional composite materials that relies solely on the physical bonding of resin, constructing a three-dimensional continuous chemical bonding network throughout the entire material. This can solve the macroscopic interface debonding problem between fibers, bundles, and layers. Furthermore, it can achieve toughening of the resin matrix and suppression of microcracks, forming full-scale reinforcement with the core-shell gradient structure. The carbon nanotubes themselves are high-strength, high-modulus nano-reinforcing phases. When uniformly dispersed in the resin matrix between fibers, they can, on the one hand, improve the cohesive strength of the resin matrix through bridging, and on the other hand, prevent the propagation of microcracks under load through the nano-pinning effect, especially the initiation and extension of cracks in the interlayer region. This forms a full-scale interface and performance reinforcement from the inside of the single filament, between the fibers, and the entire resin matrix, thereby improving the interlayer shear strength.

[0009] Furthermore, the SiC nanowire interlayer is a SiC nanowire vertically grown on the surface of the carbon fiber core layer. The SiC nanowires and the carbon fiber core layer are covalently bonded. The glass fiber shell layer is melt-permeated into the gaps between the SiC nanowires, forming an interpenetrating chemical bond structure with the SiC nanowires. The diameter of the SiC nanowires is 30-80 nm, the length is 1-3 μm, and the aspect ratio is 20-100. The diameter of the carbon fiber core layer is 5-8 μm, and the monofilament-level coating thickness of the glass fiber shell layer is 2-6 μm. The mass ratio of the hybrid fibers is: 30%-70% carbon fiber core layer, 1%-5% SiC nanowire interlayer, and the remainder is glass fiber shell layer.

[0010] Furthermore, phosphorus-nitrogen hyperbranched polyamide amine is grafted in situ onto the outer surface of the glass fiber shell. One end of the phosphorus-nitrogen hyperbranched polyamide amine is covalently bonded to the glass fiber shell through a silicon-oxygen bond, and the epoxy end group at the other end forms a covalently bonded interpenetrating crosslink with the resin matrix. The phosphorus-nitrogen hyperbranched polyamide amine accounts for 1%-4% of the total amount of mixed fibers. In situ grafting of phosphorus-nitrogen hyperbranched polyamide amine (PNA) onto the outer surface of the glass fiber shell. The end groups of the phosphorus-nitrogen hyperbranched polyamide amine are epoxy groups, which can also undergo covalent reactions with the amino groups of the aminated carbon nanotubes. At this time, the carbon nanotubes are equivalent to bridging the hyperbranched polymer layers on the surfaces of adjacent fibers, further enhancing the full-chain chemical bonding of the carbon fiber core, SiC transition layer, glass fiber shell, hyperbranched polymer interface layer, carbon nanotube bridging and resin matrix, achieving 100% stress transfer from the reinforcing phase to the resin matrix, while simultaneously strengthening the interfacial flame retardant and weather-resistant protection effects.

[0011] Further, the degree of branching of the phosphorus-nitrogen type hyperbranched polyamide amine is 0.6-0.9, the number average molecular weight is 3000-8000 g / mol, the phosphorus content is ≥8%, and the nitrogen content is ≥12%; the resin matrix comprises the following components by weight: 100 parts of bisphenol A type epoxy resin, 20-30 parts of aromatic amine curing agent, 3-8 parts of carboxyl-terminated butadiene-acrylonitrile rubber, and 0.3-0.8 parts of accelerator; the silicon content of the bisphenol A type epoxy resin is 2%-5%, and the epoxy value is 0.48-0.54 eq / 100g.

[0012] Further, the carbon fiber is one or more of T300, T700, and T800 type polyacrylonitrile-based carbon fibers, and its morphology is one of continuous fiber cloth, chopped fiber, or long filament bundle; the glass fiber is alkali-free glass fiber, and its morphology is one of continuous fiber cloth, chopped fiber, or long filament bundle; the aminated carbon nanotubes are multi-walled carbon nanotubes with a diameter of 8-20 nm, a length of 5-20 μm, and an amino content of 0.5-2.5 mmol / g; the epoxy resin is one or two of bisphenol A type epoxy resins E-44 and E-51; the phosphorus-nitrogen modified aromatic amine curing agent is DOPO modified diaminodiphenylmethane curing agent with a phosphorus content ≥6% and a nitrogen content ≥5%; the accelerator is DMP-30.

[0013] A method for preparing a carbon fiber and glass fiber composite modified material, the method comprising the following steps: S1 Carbon Fiber Surface Modification: After removing the sizing agent from the carbon fiber, mild etching with supercritical CO2 fluid is used instead of low-temperature plasma treatment. The process parameters are: temperature 40-60℃, pressure 10-15MPa, etching time 30-60min, and entrainer is 3-5wt% ethanol aqueous solution. After low-temperature plasma treatment, it is immersed in dopamine Tris-HCl buffer for coating modification. After washing and drying, polydopamine modified carbon fiber is obtained. The process parameters of the low-temperature plasma treatment are: argon atmosphere, treatment power 100-300W, treatment time 5-15min; the concentration of the dopamine Tris-HCl buffer is 1-3g / L, pH value is 8.0-8.5, modification time is 12-24h, modification temperature is room temperature, and the reaction is carried out in the dark. S2 Glass Fiber Surface Modification: After removing the sizing agent from the glass fiber, it is etched with alkali, then immersed in an epoxy silane coupling agent solution for grafting modification. After washing and drying, epoxy-modified glass fiber is obtained. The alkali etching uses a 3-8 wt% NaOH solution, and the immersion time is 30-60 min. The epoxy silane coupling agent solution is KH-560, with a concentration of 3-6 wt%, and the solvent is an aqueous ethanol solution. The grafting reaction temperature is 50-70℃, and the reaction time is 2-4 h. S3 Hybrid Fiber Construction: The hybrid fiber is either an independent hybrid fiber or a core-shell coaxial hybrid fiber. The independent hybrid fiber is constructed as follows: Polydopamine-modified carbon fiber and epoxy-modified glass fiber are mixed in a preset ratio, immersed in a dispersion containing aminated carbon nanotubes, ultrasonically treated, and then dried to obtain a carbon nanotube-bridged hybrid fiber; In the preparation of the core-shell coaxial hybrid fiber, after the preparation of polydopamine-modified carbon fiber in step S1, a step of low-temperature molten salt-assisted in-situ growth of SiC nanowire intermediate layer is added: the polydopamine-modified carbon fiber is immersed in a dispersion containing... The precursor dispersion comprises, by mass, 10-15 parts of silicon source, 5-8 parts of carbon source, 20-30 parts of eutectic salt, and 50-60 parts of anhydrous ethanol; the silicon source is one or both of nano-silicon powder and tetraethyl orthosilicate, the carbon source is one or both of glucose and phenolic resin, and the eutectic salt is a NaCl-NaF binary eutectic salt with a melting point ≤680℃; the heating rate of the low-temperature heat treatment is 3-5℃ / min, and the holding time is 1-2h; subsequently, after dip coating and drying, it is placed... SiC nanowires are vertically grown on the surface of carbon fibers by low-temperature heat treatment at 720-780℃ in an inert atmosphere to obtain carbon fibers with a SiC nanowire transition layer. The core-shell coaxial hybrid fiber is constructed as follows: a dual-cavity coaxial coating mold is used, with carbon fibers with a SiC nanowire intermediate layer as the inner core traction body and borosilicate glass melt as the coating layer melt. During the traction process, the glass melt coaxially and uniformly coats the carbon fibers. The temperature of the borosilicate glass melt is 950-1050℃, and the traction speed is 5-15 m / min. The coating thickness of the shell is controlled by the ratio of the traction rate to the mold cavity diameter; the glass fiber melt penetrates into the interlayer gap of the SiC nanowires, and after cooling and shaping, a fiber precursor is obtained. The surface of the fiber precursor is then modified by grafting with an epoxy silane coupling agent, followed by immersion in a dispersion containing aminated carbon nanotubes, ultrasonic treatment, and drying to obtain a hybrid fiber bridged by carbon nanotubes; the dispersion is an aqueous ethanol solution, the ultrasonic treatment power is 200-400W, the ultrasonic time is 30-60min, the drying temperature is 60-80℃, and the drying time is 1-3h. S4 resin matrix preparation: According to the preset mass parts, epoxy resin, phosphorus-nitrogen modified aromatic amine curing agent, terminal epoxy butadiene nitrile rubber and accelerator are mixed and stirred evenly, and the resin solution is obtained after vacuum degassing. S5 prepreg preparation: The hybrid fibers are immersed in a resin solution, and the resin content is controlled by an impregnation process to obtain the prepreg; the impregnation process is either a hot-melt method or a solution method, and the resin content of the prepreg is controlled to be 35%-45%; S6 Curing and Molding: After laying the prepreg in a preset direction, the laying method is 0° / 90° orthogonal laying, and the number of layers is 4-16; it is placed in a mold for hot pressing and curing. The hot pressing and curing process is: 110-130℃ for 1 hour + 140-160℃ for 2 hours + 170-190℃ for 1 hour, and the molding pressure is 3-5 MPa; after cooling and demolding, carbon fiber and glass fiber composite modified material is obtained.

[0014] Furthermore, after the surface of the fiber precursor is modified by grafting with an epoxy silane coupling agent, it is first treated with an amino silane coupling agent and then immersed in a reaction solution containing phosphorus-nitrogen hyperbranched polyamide amine monomers for in-situ stepwise polymerization and grafting. After washing and drying, it is then immersed in a dispersion containing aminated carbon nanotubes.

[0015] Compared with the prior art, the carbon fiber and glass fiber composite modified material and its preparation method of the present invention have the following advantages: 1. Constructing a fully chemically bonded three-dimensional hybrid network to completely solve the interface compatibility problem: Aminated carbon nanotubes act as "molecular bridges" and covalently bond with polydopamine-modified carbon fibers and epoxy-modified glass fibers, achieving integrated connection between carbon fibers and glass fibers, fundamentally eliminating interface defects between the two types of fibers and significantly improving the interface bonding force.

[0016] 2. Constructing a monofilament-level core-shell gradient structure to eliminate the inherent defect of modulus mismatch: Carbon fiber and glass fiber are designed as a monofilament-level coaxial core-shell gradient structure. A modulus gradient transition layer is constructed using SiC nanowires, achieving continuous modulus adaptation from high-modulus carbon fiber to low-modulus glass fiber. This completely eliminates the modulus abrupt changes and stress concentration inherent in traditional hybrid composites, fundamentally solving the inherent defects of deformation incoordination and easy microcrack initiation. Simultaneously, the glass fiber shell effectively protects the carbon fiber core, preventing wear and breakage during weaving and service, significantly improving the material's fatigue resistance.

[0017] 3. Fully cross-linked interpenetrating interface system, achieving synergistic leap in multiple properties: A fully chemically bonded interface system from carbon fiber core to resin matrix: SiC nanowires are covalently bonded to carbon fibers, glass fiber melt and SiC nanowires form an interpenetrating chemical bond structure, and phosphorus-nitrogen hyperbranched polymers grafted in situ on the glass fiber surface form an interpenetrating cross-linked network with the resin matrix, achieving 100% stress transfer efficiency. At the same time, the "nanopinion" effect of SiC nanowires can effectively prevent the propagation of microcracks, and the SiC ceramic phase and phosphorus-nitrogen flame retardant elements at the interface can form a continuous ceramic protective layer, blocking the thermo-oxidative erosion channel. Without the need to add a large amount of inorganic flame retardant, the limiting oxygen index of the composite material can reach more than 38%, achieving the UL94V-0 flame retardant rating. The interlaminar shear strength is increased by more than 50% compared with traditional hybrid materials, the impact strength is increased by more than 60%, and the performance retention rate after 1000 hours of damp heat aging is more than 95%, achieving a synergistic balance of high strength, high toughness, high flame retardancy, and high weather resistance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the preparation method of carbon fiber and glass fiber composite modified material according to Example 1 of the present invention.

[0019] Figure 2 This is a schematic diagram of the preparation method of carbon fiber and glass fiber composite modified material according to Example 6 of the present invention. Detailed Implementation

[0020] The carbon fiber and glass fiber composite modified material of the present invention comprises the following components in the following mass ratio: 30%-60% reinforcing phase, with the remainder being a resin matrix, wherein the reinforcing phase is a hybrid fiber; the hybrid fiber is formed by chemically bonding polydopamine-modified carbon fiber and epoxy-modified glass fiber through aminated carbon nanotubes, and the mass ratio of carbon fiber to glass fiber is 1~3:3~1; the mass of the aminated carbon nanotubes is 0.5%-3% of the total mass of carbon fiber and glass fiber; the role of the aminated carbon nanotubes here is to achieve the integration of carbon fiber and glass fiber into a heterogeneous fiber structure through the carbon nanotubes. Sub-bridges address the interfacial bonding problem between two completely different fibers; in the core-shell scheme, the outer surface of all fibers is a glass fiber shell with epoxy groups. The amino groups at both ends of the aminated carbon nanotubes can covalently bond with the epoxy groups on the surfaces of two adjacent core-shell fibers, which is equivalent to achieving molecular-level "welding" of adjacent fibers through carbon nanotubes. This completely replaces the weak interface of traditional composite materials that relies solely on physical bonding with resin, constructing a three-dimensional continuous chemical bonding network that runs through the entire material. This solves the macroscopic interface debonding problem between fibers, bundles, and layers.

[0021] The resin matrix comprises the following components in parts by weight: 100 parts epoxy resin, 25-35 parts phosphorus-nitrogen modified aromatic amine curing agent, 5-10 parts terminal epoxy butadiene-acrylonitrile rubber, and 0.5-1 parts accelerator.

[0022] The hybrid fiber has a coaxial core-shell gradient structure, and the hybrid fiber consists of a carbon fiber core layer, a SiC nanowire intermediate layer, and a glass fiber shell layer from the inside to the outside; the carbon fiber core layer is polydopamine modified carbon fiber, and the glass fiber shell layer is epoxy-modified glass fiber.

[0023] The role of aminated carbon nanotubes here is as follows: Since the outer surface of the glass fiber shell is covered with epoxy groups, and the amino groups at both ends of the aminated carbon nanotubes can covalently bond with the epoxy groups on the surfaces of two adjacent fibers, the adjacent fibers are "welded" at the molecular level through the carbon nanotubes. This completely replaces the weak interface in traditional composite materials that relies solely on the physical bonding of resin, constructing a three-dimensional continuous chemical bonding network throughout the entire material. This can solve the macroscopic interface debonding problem between fibers, bundles, and layers. Furthermore, it can achieve toughening of the resin matrix and suppression of microcracks, forming full-scale reinforcement with the core-shell gradient structure. The carbon nanotubes themselves are high-strength, high-modulus nano-reinforcing phases. When uniformly dispersed in the resin matrix between fibers, they can, on the one hand, improve the cohesive strength of the resin matrix through bridging, and on the other hand, prevent the propagation of microcracks under load through the nano-pinning effect, especially the initiation and extension of cracks in the interlayer region. This forms a full-scale interface and performance reinforcement from the inside of the single filament, between the fibers, and the entire resin matrix, thereby improving the interlayer shear strength.

[0024] The SiC nanowire interlayer consists of SiC nanowires grown vertically on the surface of the carbon fiber core layer. The SiC nanowires are covalently bonded to the carbon fiber core layer. The glass fiber shell is fused and infiltrated into the gaps between the SiC nanowires, forming an interpenetrating chemical bond structure with the SiC nanowires. The diameter of the SiC nanowires is 30-80 nm, the length is 1-3 μm, and the aspect ratio is 20-100. The diameter of the carbon fiber core layer is 5-8 μm, and the monofilament-level coating thickness of the glass fiber shell is 2-6 μm. The mass ratio of the hybrid fibers is: 30%-70% carbon fiber core layer, 1%-5% SiC nanowire interlayer, and the remainder is glass fiber shell.

[0025] The outer surface of the glass fiber shell is in situ grafted with phosphorus-nitrogen hyperbranched polyamide amine. One end of the phosphorus-nitrogen hyperbranched polyamide amine is covalently bonded to the glass fiber shell through a silicon-oxygen bond, while the epoxy end group at the other end forms a covalently bonded interpenetrating crosslink with the resin matrix. The phosphorus-nitrogen hyperbranched polyamide amine accounts for 1%-4% of the total mixed fibers. The phosphorus-nitrogen hyperbranched polyamide amine (phosphorus-nitrogen hyperbranched polyamide amine) is in situ grafted onto the outer surface of the glass fiber shell. The end group of the phosphorus-nitrogen hyperbranched polyamide amine is an epoxy group, which can also undergo a covalent reaction with the amino group of the aminated carbon nanotube. At this time, the carbon nanotube is equivalent to bridging the hyperbranched polymer layer on the surface of adjacent fibers, further improving the full-chain chemical bonding of the carbon fiber core layer, SiC transition layer, glass fiber shell layer, hyperbranched polymer interface layer, carbon nanotube bridging and resin matrix, realizing 100% stress transfer from the reinforcing phase to the resin matrix, while simultaneously enhancing the interfacial flame retardant and weather protection effects.

[0026] The degree of branching of the phosphorus-nitrogen type hyperbranched polyamide amine is 0.6-0.9, the number average molecular weight is 3000-8000 g / mol, the phosphorus content is ≥8%, and the nitrogen content is ≥12%. The resin matrix comprises the following components in parts by weight: 100 parts of bisphenol A type epoxy resin, 20-30 parts of aromatic amine curing agent, 3-8 parts of carboxyl-terminated butadiene-acrylonitrile rubber, and 0.3-0.8 parts of accelerator. The silicon content of the bisphenol A type epoxy resin is 2%-5%, and the epoxy value is 0.48-0.54 eq / 100g.

[0027] The carbon fiber is one or more of T300, T700, and T800 type polyacrylonitrile-based carbon fibers, and is in the form of continuous fiber cloth, chopped fiber, or filament bundle; the glass fiber is alkali-free glass fiber, and is in the form of continuous fiber cloth, chopped fiber, or filament bundle; the aminated carbon nanotubes are multi-walled carbon nanotubes with a diameter of 8-20 nm, a length of 5-20 μm, and an amino content of 0.5-2.5 mmol / g; the epoxy resin is one or two of bisphenol A type epoxy resins E-44 and E-51; the phosphorus-nitrogen modified aromatic amine curing agent is DOPO modified diaminodiphenylmethane curing agent with a phosphorus content ≥6% and a nitrogen content ≥5%; the accelerator is DMP-30.

[0028] A method for preparing a carbon fiber and glass fiber composite modified material, the method comprising the following steps: S1 Carbon Fiber Surface Modification: After removing the sizing agent from the carbon fiber, mild etching with supercritical CO2 fluid is used instead of low-temperature plasma treatment. The process parameters are: temperature 40-60℃, pressure 10-15MPa, etching time 30-60min, and entrainer is 3-5wt% ethanol aqueous solution. After low-temperature plasma treatment, it is immersed in dopamine Tris-HCl buffer for coating modification. After washing and drying, polydopamine modified carbon fiber is obtained. The process parameters of the low-temperature plasma treatment are: argon atmosphere, treatment power 100-300W, treatment time 5-15min; the concentration of the dopamine Tris-HCl buffer is 1-3g / L, pH value is 8.0-8.5, modification time is 12-24h, modification temperature is room temperature, and the reaction is carried out in the dark. S2 Glass Fiber Surface Modification: After removing the sizing agent from the glass fiber, it is etched with alkali, then immersed in an epoxy silane coupling agent solution for grafting modification. After washing and drying, epoxy-modified glass fiber is obtained. The alkali etching uses a 3-8 wt% NaOH solution, and the immersion time is 30-60 min. The epoxy silane coupling agent solution is KH-560, with a concentration of 3-6 wt%, and the solvent is an aqueous ethanol solution. The grafting reaction temperature is 50-70℃, and the reaction time is 2-4 h. S3 Hybrid Fiber Construction: The hybrid fiber is either an independent hybrid fiber or a core-shell coaxial hybrid fiber. The independent hybrid fiber is constructed as follows: Polydopamine-modified carbon fiber and epoxy-modified glass fiber are mixed in a preset ratio, immersed in a dispersion containing aminated carbon nanotubes, ultrasonically treated, and then dried to obtain a carbon nanotube-bridged hybrid fiber; In the preparation of the core-shell coaxial hybrid fiber, after the preparation of polydopamine-modified carbon fiber in step S1, a step of low-temperature molten salt-assisted in-situ growth of SiC nanowire intermediate layer is added: the polydopamine-modified carbon fiber is immersed in a dispersion containing... The precursor dispersion comprises, by mass, 10-15 parts of silicon source, 5-8 parts of carbon source, 20-30 parts of eutectic salt, and 50-60 parts of anhydrous ethanol; the silicon source is one or both of nano-silicon powder and tetraethyl orthosilicate, the carbon source is one or both of glucose and phenolic resin, and the eutectic salt is a NaCl-NaF binary eutectic salt with a melting point ≤680℃; the heating rate of the low-temperature heat treatment is 3-5℃ / min, and the holding time is 1-2h; subsequently, after dip coating and drying, it is placed... SiC nanowires are vertically grown on the surface of carbon fibers by low-temperature heat treatment at 720-780℃ in an inert atmosphere to obtain carbon fibers with a SiC nanowire transition layer. The core-shell coaxial hybrid fiber is constructed as follows: a dual-cavity coaxial coating mold is used, with carbon fibers with a SiC nanowire intermediate layer as the inner core traction body and borosilicate glass melt as the coating layer melt. During the traction process, the glass melt coaxially and uniformly coats the carbon fibers. The temperature of the borosilicate glass melt is 950-1050℃, and the traction speed is 5-15 m / min. The coating thickness of the shell is controlled by the ratio of the traction rate to the mold cavity diameter; the glass fiber melt penetrates into the interlayer gap of the SiC nanowires, and after cooling and shaping, a fiber precursor is obtained. The surface of the fiber precursor is then modified by grafting with an epoxy silane coupling agent, followed by immersion in a dispersion containing aminated carbon nanotubes, ultrasonic treatment, and drying to obtain a hybrid fiber bridged by carbon nanotubes; the dispersion is an aqueous ethanol solution, the ultrasonic treatment power is 200-400W, the ultrasonic time is 30-60min, the drying temperature is 60-80℃, and the drying time is 1-3h. S4 resin matrix preparation: According to the preset mass parts, epoxy resin, phosphorus-nitrogen modified aromatic amine curing agent, terminal epoxy butadiene nitrile rubber and accelerator are mixed and stirred evenly, and the resin solution is obtained after vacuum degassing. S5 prepreg preparation: The hybrid fibers are immersed in a resin solution, and the resin content is controlled by an impregnation process to obtain the prepreg; the impregnation process is either a hot-melt method or a solution method, and the resin content of the prepreg is controlled to be 35%-45%; S6 Curing and Molding: After laying the prepreg in a preset direction, the laying method is 0° / 90° orthogonal laying, and the number of layers is 4-16; it is placed in a mold for hot pressing and curing. The hot pressing and curing process is: 110-130℃ for 1 hour + 140-160℃ for 2 hours + 170-190℃ for 1 hour, and the molding pressure is 3-5 MPa; after cooling and demolding, carbon fiber and glass fiber composite modified material is obtained. Example 1:

[0029] like Figure 1 As shown, the carbon fiber and glass fiber composite modified material of the present invention is prepared according to the following steps: S1 carbon fiber surface modification: Take T700 carbon fiber cloth, extract with acetone Soxhlet for 24h to remove sizing agent, treat with argon low temperature plasma at 200W power for 10min; then put it into 2g / L dopamine Tris-HCl buffer (pH=8.5), stir at room temperature in the dark for 18h, take it out and rinse it 3 times with deionized water, and vacuum dry at 60℃ for 12h to obtain polydopamine modified carbon fiber. S2 glass fiber surface modification: Take alkali-free glass fiber cloth, extract it with acetone Soxhlet for 24 h to remove the sizing agent, immerse it in 5wt% NaOH solution for 45 min for etching, rinse it with deionized water until neutral, and vacuum dry it at 80℃ for 12 h; then put it into 5wt% KH-560 ethanol aqueous solution, reflux it at 60℃ for 3 h, take it out and rinse it with ethanol 3 times, and vacuum dry it at 80℃ for 12 h to obtain epoxy-modified glass fiber; Construction of S3 hybrid fiber network (independent hybrid fibers): Polydopamine-modified carbon fibers and epoxy-modified glass fibers were mixed at a mass ratio of 1:1 and placed in an ethanol aqueous solution containing 1.5 wt% aminated multi-walled carbon nanotubes. The mixture was ultrasonically dispersed at 300 W for 45 min, and then vacuum dried at 80 °C for 2 h to obtain a carbon nanotube-bridged carbon fiber-glass fiber hybrid fiber network. The mass of the aminated carbon nanotubes was 1.5% of the total mass of the carbon fibers and glass fibers. S4 resin matrix preparation: By weight, take 100 parts of E-51 epoxy resin, 30 parts of DOPO modified diaminodiphenylmethane curing agent (phosphorus content 8%, nitrogen content 6%), 8 parts of terminal epoxy butadiene nitrile rubber, and 0.8 parts of DMP-30, stir and mix at 60℃ for 30 min, and degas under vacuum for 15 min to obtain resin solution. S5 prepreg preparation: The hybrid fiber network is immersed in the resin solution and impregnated by hot melt method. The resin solution content is controlled to be 40%. The mixture is left at room temperature for 24 hours to obtain the prepreg. S6 Curing and Molding: The prepreg is laid in 8 layers at 0° / 90° orthogonal layers and placed in a flat mold. It is then hot-pressed and cured using a flat vulcanizing machine. The curing process is 120°C for 1 hour, 150°C for 2 hours, and 180°C for 1 hour. The molding pressure is 4MPa. After curing, the material is allowed to cool naturally to room temperature and then demolded to obtain the finished product.

[0030] Examples 2 to 5: The only difference between Examples 2-5 and Example 1 is the adjustment of the raw material ratio and process parameters. The specific parameter adjustments are shown in Table 1 below. The remaining steps are the same as in Example 1.

[0031]

[0032] Example 6: like Figure 2 As shown, the carbon fiber and glass fiber composite modified material of the present invention is prepared according to the following steps: S1 carbon fiber surface modification: T700 carbon fiber bundles were extracted with acetone Soxhlet for 24 hours to remove the sizing agent, placed in a supercritical reactor, and etched with supercritical CO2 fluid at a temperature of 50℃, a pressure of 12MPa, and an etching time of 45min. The entrainer was a 4wt% ethanol aqueous solution. After depressurization, the bundles were removed and vacuum dried at 80℃ for 12 hours. Then, they were immersed in 2g / L dopamine Tris-HCl buffer (pH=8.5) and reacted at room temperature in the dark for 18 hours. After washing and drying, polydopamine-modified carbon fibers were obtained. S2 In-situ Growth of SiC Nanowire Intermediate Layer: By mass, 12 parts of nano-silicon powder, 6 parts of glucose, and 25 parts of NaCl-NaF binary eutectic salt were added to 57 parts of anhydrous ethanol and ultrasonically dispersed for 30 min to obtain a precursor dispersion. Polydopamine-modified carbon fibers were immersed in the precursor dispersion and coated by dip coating at a rate of 5 m / min. After drying at room temperature, the carbon fibers were placed in a tube furnace and heated to 750℃ at 4℃ / min under an argon atmosphere. The temperature was held for 1.5 h and then cooled with the furnace to obtain carbon fibers with a SiC nanowire transition layer. S3 coaxial melt coating construction of glass fiber shell: A dual-cavity coaxial coating mold is used. The inner cavity is filled with carbon fiber with SiC nanowire transition layer and the traction rate is 10m / min. The outer cavity is filled with 1000℃ borosilicate alkali-free glass melt. Coaxial coating is completed during the traction process. After air cooling and shaping, a core-shell structured fiber precursor is obtained. The precursor is immersed in 5wt% KH-560 ethanol aqueous solution and refluxed at 60℃ for 3h. After washing and drying, an epoxy-modified glass fiber core-shell structured fiber is obtained. S4 In-situ grafted phosphorus-nitrogen hyperbranched polyamide amine: The core-shell structured fiber was immersed in 5wt% KH-550 ethanol aqueous solution and treated at 60℃ for 3h. After washing and drying with ethanol, it was immersed in DMF reaction solution containing phosphorus-nitrogen hyperbranched polyamide amine monomer and polymerized in situ at 90℃ for 5h. After Soxhlet extraction with anhydrous ethanol for 12h, the surface-functionalized core-shell structured gradient hybrid fiber was obtained. Construction of S5 hybrid fiber network: Core-shell structured gradient hybrid fibers were immersed in an ethanol aqueous solution containing 1.5 wt% aminated multi-walled carbon nanotubes, ultrasonically dispersed at 300 W for 45 min, and dried to obtain a carbon nanotube-bridged hybrid fiber network. S6 resin matrix preparation: By weight, take 100 parts of bisphenol A type epoxy resin (silicon content 3%, epoxy value 0.51eq / 100g), 25 parts of diaminodiphenylmethane curing agent, 5 parts of carboxyl-terminated butadiene-acrylonitrile rubber, and 0.5 parts of DMP-30 accelerator, stir and mix at 60℃ for 30 min, and degas under vacuum to obtain resin solution. S7 Prepreg Preparation and Curing: The mixed fiber network is woven into a plain weave fabric, immersed in resin solution to make a prepreg with a resin content of 40%. Ten layers are laid in an orthogonal pattern at 0° / 90°. The hot-press curing process is 110°C for 1 hour + 135°C for 2 hours + 165°C for 1 hour, with a molding pressure of 4MPa. After cooling and demolding, the finished product is obtained.

[0033] Examples 7 to 10: The only difference between Examples 7-10 and Example 6 is the adjustment of the raw material ratio and process parameters. The specific parameter adjustments are shown in Table 2 below. The remaining steps are the same as in Example 6.

[0034]

[0035] Comparative Example 1: This comparative example is a traditional unmodified interlaminar hybrid carbon fiber / glass fiber composite material with a carbon fiber to glass fiber mass ratio of 1:1 and a total fiber content of 50%. The resin matrix is ​​the same as in Example 1, and the same impregnation and curing process is used for preparation.

[0036] Comparative Example 2: This comparative example is a pure carbon fiber composite material with a fiber content of 50%. The resin matrix is ​​the same as that in Example 1, and it is prepared using the same impregnation and curing process.

[0037] Comparative Example 3: This comparative example is a core-shell composite material without a SiC nanowire transition layer. The remaining steps are the same as in Example 6, except that the SiC nanowire growth step is omitted.

[0038] Performance testing: The composite materials prepared in the above examples and comparative examples were subjected to performance testing according to the following standards: Tensile properties: GB / T1447-2005; Interlaminar shear strength (ILSS): GB / T1450.1-2005; Impact strength: GB / T1451-2005; Limiting Oxygen Index (LOI): GB / T2406.2-2009; Flame retardant rating: UL94-2016; Resistance to damp heat aging: After aging at 80℃ and 95%RH for 1000 hours, the ILSS retention rate was calculated. The relative cost is shown in the table below, with the cost of the pure carbon fiber composite material in Comparative Example 2 set at 100.

[0039] The performance test results show that: the overall performance of Example 1 of the present invention is far superior to that of the traditional hybrid material of Comparative Example 1, with an increase of more than 30% in interlaminar shear strength, more than 40% in impact strength, and significant improvement in flame retardancy and damp heat resistance, while the cost is only 60% of that of pure carbon fiber material, achieving a balance between high performance and low cost; the performance of Example 6 of the present invention achieves a leapfrog improvement, with an increase of more than 50% in interlaminar shear strength and more than 60% in impact strength compared to the traditional hybrid material, and all performances surpassing those of pure carbon fiber composite material, while the cost is only 65% ​​of that of pure carbon fiber material, verifying the significant advantages of the core-shell gradient structure design; compared with Comparative Example 3, Example 6 has an increase of more than 21% in interlaminar shear strength and more than 27% in impact strength.

[0040] Example 11: This embodiment is used for the LFT-D process. For example, when used in general automotive structural parts, the specific steps are as follows: A hybrid fiber network is constructed according to Example 6 to obtain the hybrid fiber network; then, it is prepared according to the following steps: First, a continuous preparation of core-shell structure gradient hybrid fibers was carried out: the mass ratio of carbon fiber core to glass fiber shell was 1:1, the traction rate was 12m / min, the glass fiber shell coating thickness was 5μm, the SiC nanowire surface density was 20 strands / μm², and the glass fiber shell was modified with KH-560 epoxy group. Next, thermoplastic adaptable in-situ surface modification was carried out: the core-shell structured fibers were continuously passed into a treatment tank containing 5wt% KH-550 ethanol aqueous solution and treated at 70℃ for 2h. After washing and drying with ethanol, they were passed into a DMF reactor containing maleic anhydride-terminated phosphorus-nitrogen hyperbranched polyamide monomers and subjected to in-situ grafting reaction at 110℃ for 4h. After washing with ethanol and hot air drying at 100℃, continuous long filament bundles of surface functionalized fibers were obtained, in which the hyperbranched polyamide had a branching degree of 0.85, a number average molecular weight of 6000 g / mol, a Td5%=335℃, and a grafting mass ratio of 2.5%. Finally, the LFT-D online integrated molding process is completed: the surface-functionalized fibers are fed into the LFT-D twin-screw production line through a yarn rack, and after being opened by pre-dispersing rollers, they are fed into the twin-screw extruder. At the same time, the polypropylene matrix and additives are metered and fed in. The screw temperature is 190-230℃, the screw speed is 300rpm, and the fiber residence time is 45s. After mixing and impregnation, the fibers are extruded through the die and directly fed into the molding press. The fibers are then molded at 180℃ and 10MPa, and cooled and demolded to obtain the LFT-D product. Based on the total mass of the LFT-D product, the reinforcing phase accounts for 30%, the polypropylene matrix 68%, the antioxidant 1010 0.5%, and the lubricant calcium stearate 1.5%.

[0041] After preparing the LFT-D product according to Example 11, its performance was tested, and the following results were obtained: tensile strength 138 MPa, flexural strength 186 MPa, impact strength 32.5 (kJ / m²), average fiber length 1.82 mm, and LOI. 30.5%; The carbon fiber and glass fiber composite modified material produced by this invention, when applied to the LFT-D process, can improve the shear resistance structure of LFT-D products and completely solve the pain points of easy breakage and low length retention of carbon fiber. Specifically, this invention is designed for the strong shear conditions of LFT-D twin-screw extruders. It forms 360° all-round protection for the carbon fiber core layer through a high-toughness glass fiber shell layer, avoiding direct friction and wear between the carbon fiber and the equipment during conveying and mixing. At the same time, it significantly improves the bending and shear resistance of the fiber filaments. By controlling the areal density of SiC nanowires to 15-30 fibers / μm², a strongly anchored interpenetrating structure is formed, completely eliminating the core-shell debonding problem under shear action. This embodiment keeps the average fiber length in the product at 1.82mm, which is much higher than the 0.2-0.5mm of ordinary carbon fiber LFT-D products. It fully utilizes the bridging and reinforcing effect of long fibers. The bending strength and impact strength of the composite material are increased by more than 40% compared with ordinary carbon fiber LFT-D materials.

[0042] The above embodiments are merely preferred embodiments of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention are included within the scope of the present invention.

Claims

1. A carbon fiber and glass fiber composite modified material, characterized in that: The product comprises the following components in the following mass ratio: 30%-60% reinforcing phase, with the remainder being resin matrix. The reinforcing phase is a hybrid fiber. The hybrid fiber is formed by chemically bonding polydopamine-modified carbon fiber and epoxy-modified glass fiber through aminated carbon nanotubes. The mass ratio of carbon fiber to glass fiber is 1~3:3~1. The mass of the aminated carbon nanotubes is 0.5%-3% of the total mass of carbon fiber and glass fiber.

2. The carbon fiber and glass fiber composite modified material according to claim 1, characterized in that: The resin matrix comprises the following components in parts by weight: 100 parts epoxy resin, 25-35 parts phosphorus-nitrogen modified aromatic amine curing agent, 5-10 parts terminal epoxy butadiene-acrylonitrile rubber, and 0.5-1 parts accelerator.

3. The carbon fiber and glass fiber composite modified material according to claim 1, characterized in that: The hybrid fiber has a coaxial core-shell gradient structure, and the hybrid fiber consists of a carbon fiber core layer, a SiC nanowire intermediate layer, and a glass fiber shell layer from the inside to the outside; the carbon fiber core layer is polydopamine modified carbon fiber, and the glass fiber shell layer is epoxy-modified glass fiber.

4. The carbon fiber and glass fiber composite modified material according to claim 3, characterized in that: The SiC nanowire interlayer consists of SiC nanowires grown vertically on the surface of the carbon fiber core layer. The SiC nanowires are covalently bonded to the carbon fiber core layer. The glass fiber shell is fused and infiltrated into the gaps between the SiC nanowires, forming an interpenetrating chemical bond structure with the SiC nanowires. The diameter of the SiC nanowires is 30-80 nm, the length is 1-3 μm, and the aspect ratio is 20-100. The diameter of the carbon fiber core layer is 5-8 μm, and the monofilament-level coating thickness of the glass fiber shell is 2-6 μm. The mass ratio of the hybrid fibers is: 30%-70% carbon fiber core layer, 1%-5% SiC nanowire interlayer, and the remainder is glass fiber shell.

5. The carbon fiber and glass fiber composite modified material according to claim 3, characterized in that: The outer surface of the glass fiber shell is grafted in situ with phosphorus-nitrogen hyperbranched polyamide amine. One end of the phosphorus-nitrogen hyperbranched polyamide amine is covalently bonded to the glass fiber shell through a silicon-oxygen bond, and the epoxy end group at the other end forms a covalently bonded interpenetrating crosslink with the resin matrix. The phosphorus-nitrogen hyperbranched polyamide amine accounts for 1%-4% of the total amount of mixed fibers.

6. The carbon fiber and glass fiber composite modified material according to claim 5, characterized in that: The degree of branching of the phosphorus-nitrogen type hyperbranched polyamide amine is 0.6-0.9, the number average molecular weight is 3000-8000 g / mol, the phosphorus content is ≥8%, and the nitrogen content is ≥12%. The resin matrix comprises the following components in parts by weight: 100 parts of bisphenol A type epoxy resin, 20-30 parts of aromatic amine curing agent, 3-8 parts of carboxyl-terminated butadiene-acrylonitrile rubber, and 0.3-0.8 parts of accelerator. The silicon content of the bisphenol A type epoxy resin is 2%-5%, and the epoxy value is 0.48-0.54 eq / 100g.

7. The carbon fiber and glass fiber composite modified material according to claim 1, characterized in that: The carbon fiber is one or more of T300, T700, and T800 type polyacrylonitrile-based carbon fibers, and is in the form of continuous fiber cloth, chopped fiber, or filament bundle; the glass fiber is alkali-free glass fiber, and is in the form of continuous fiber cloth, chopped fiber, or filament bundle; the aminated carbon nanotubes are multi-walled carbon nanotubes with a diameter of 8-20 nm, a length of 5-20 μm, and an amino content of 0.5-2.5 mmol / g; the epoxy resin is one or two of bisphenol A type epoxy resins E-44 and E-51; the phosphorus-nitrogen modified aromatic amine curing agent is DOPO modified diaminodiphenylmethane curing agent with a phosphorus content ≥6% and a nitrogen content ≥5%; the accelerator is DMP-30.

8. A method for preparing a carbon fiber and glass fiber composite modified material, used to prepare the carbon fiber and glass fiber composite modified material according to claims 1 to 7, characterized in that, The method includes the following steps: S1 carbon fiber surface modification: After removing the sizing agent from the carbon fiber, it is treated with low-temperature plasma, then immersed in dopamine Tris-HCl buffer for coating modification, and after washing and drying, polydopamine modified carbon fiber is obtained. S2 glass fiber surface modification: After removing the sizing agent from the glass fiber, it is etched by alkaline washing, then immersed in an epoxy silane coupling agent solution for graft modification, and after washing and drying, epoxy modified glass fiber is obtained. S3 Hybrid Fiber Construction: The hybrid fiber is either an independent hybrid fiber or a core-shell coaxial hybrid fiber. The independent hybrid fiber is constructed as follows: polydopamine-modified carbon fiber and epoxy-modified glass fiber are mixed in a preset ratio, immersed in a dispersion containing aminated carbon nanotubes, ultrasonically treated, and then dried to obtain carbon nanotube-bridged hybrid fiber. The core-shell coaxial hybrid fiber is constructed as follows: a dual-cavity coaxial coating mold is used, with carbon fiber with a SiC nanowire interlayer as the inner core traction body and borosilicate glass melt as the coating layer melt. During the traction process, the glass fiber melt uniformly and coaxially coats the carbon fiber, and the glass fiber melt penetrates into the gap between the SiC nanowire interlayer. After cooling and shaping, a fiber precursor is obtained. Then, the surface of the fiber precursor is grafted with an epoxy silane coupling agent for modification. Next, it is immersed in a dispersion containing aminated carbon nanotubes, ultrasonically treated, and then dried to obtain a carbon nanotube-bridged hybrid fiber. S4 resin matrix preparation: According to the preset mass parts, epoxy resin, phosphorus-nitrogen modified aromatic amine curing agent, terminal epoxy butadiene nitrile rubber and accelerator are mixed and stirred evenly, and the resin solution is obtained after vacuum degassing. S5 Prepreg Preparation: The hybrid fibers are immersed in a resin solution, and the resin content is controlled by the impregnation process to obtain the prepreg. S6 Curing and Molding: After the prepreg is laid in a preset direction, it is placed in a mold for hot pressing and curing. After cooling and demolding, carbon fiber and glass fiber composite modified material is obtained.

9. The method for preparing carbon fiber and glass fiber composite modified materials according to claim 8, characterized in that: After the surface of the fiber precursor is modified by grafting with epoxy silane coupling agent, it is first treated with amino silane coupling agent and then immersed in a reaction solution containing phosphorus-nitrogen hyperbranched polyamide amine monomer for in-situ stepwise polymerization and grafting. After washing and drying, it is then immersed in a dispersion containing aminated carbon nanotubes.

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