High-hardness and high-toughness recyclable CFEP-SiC composite material and preparation method thereof

Abstract

The invention belongs to the technical field of advanced composite materials, and discloses a high-hardness and high-toughness recyclable CFEP-SiC composite material and a preparation method thereof. The CFEP-SiC composite material is prepared from the following raw materials in percentage by weight: 55.7 to 58.5 percent of T800-grade carbon fiber, 17.5 to 18.9 percent of bisphenol A type epoxy resin, 7.0 to 7.6 percent of alicyclic epoxy resin, 7.0 to 7.6 percent of a DDS curing agent, 0.9 to 1.1 percent of a CTBN prepolymer, 3.4 to 3.8 percent of alpha-SiC nanoparticles, 1.6 to 2.0 percent of beta-SiC whiskers, 0.25 to 0.35 percent of hydrophobic gas-phase SiO2, 0.35 to 0.45 percent of a silane coupling agent, 0.25 to 0.35 percent of a dispersing agent, 0.15 to 0.25 percent of a microcapsule catalyst and 1.6 to 2.0 percent of core-shell structure particles. Through collaborative design of multi-scale toughening, multi-dimensional reinforcing and controllable recycling functional units and in combination with a resin transfer molding (RTM) process, the hardness and toughness of the composite material are remarkably improved, the composite material is endowed with the recoverable characteristic, and the application requirements of the aerospace field are met.

Description

Technical Field

[0001] This invention belongs to the field of advanced composite materials technology, and more specifically relates to a high-hardness, high-toughness, recyclable CFEP-SiC composite material and its preparation method. Background Technology

[0002] With the rapid development and increasing demand in the aerospace field, the global demand for high-performance lightweight materials is constantly increasing. Along with technological advancements, structural components are placing increasingly higher demands on the performance of composite materials, particularly in terms of high strength, high toughness, and high reliability. Carbon fiber reinforced epoxy resin composites, due to their high specific strength, specific modulus, fatigue resistance, and chemical corrosion resistance, have become a key core material in modern applications. However, existing thermosetting CFEP technologies still have some inherent limitations in application, such as insufficient toughness, inadequate hardness, difficulty in recycling, and complex processing, making it difficult to fully meet the application requirements of the aerospace field.

[0003] Therefore, in order to solve the above problems, how to develop a new type of CFRP composite material, and improve the toughness and hardness of the material and endow it with recyclable properties by optimizing the material system and combining it with liquid molding process, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To overcome the shortcomings and deficiencies of existing technologies, this invention provides a high-hardness, high-toughness, recyclable CFEP-SiC composite material and its preparation method. Using carbon fiber as a reinforcing skeleton and epoxy resin as a matrix, the toughness and hardness of the composite material are improved by optimizing the formulation design, thereby significantly enhancing the overall performance of the composite material and endowing it with recyclable properties to meet the application needs of aerospace and sustainable development.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A high-hardness, high-toughness, and recyclable CFEP-SiC composite material comprises, by weight percentage: 55.7–58.5% T800 grade carbon fiber, 17.5–18.9% bisphenol A type epoxy resin, 7.0–7.6% alicyclic epoxy resin, 7.0–7.6% DDS curing agent, 0.9–1.1% CTBN prepolymer, 3.4–3.8% α-SiC nanoparticles, 1.6–2.0% β-SiC whiskers, 0.25–0.35% hydrophobic fumed SiO2, 0.35–0.45% silane coupling agent, 0.25–0.35% dispersant, 0.15–0.25% microencapsulated catalyst, and 1.6–2.0% core-shell structured particles.

[0006] Preferably, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0007] Preferably, the dispersant is a polyether-siloxane block copolymer.

[0008] Preferably, the core-shell structured particles are rubber core-epoxy shell, with the core being cross-linked styrene-butadiene rubber spheres with a particle size of 60-80 nm and the outer shell being an epoxy functionalized polymer with a thickness of 20-30 nm.

[0009] Preferably, the core of the microcapsule catalyst is a boron trifluoride ethylamine complex, and the capsule wall is a thermosensitive polyurethane.

[0010] Preferably, the T800 grade carbon fiber has a single filament diameter of 5.000–7.000 μm; the α-SiC nanoparticles have a particle size of 0.030–0.080 μm; and the β-SiC whiskers have a diameter of 0.1 μm and a length of 1.5–3.0 μm.

[0011] Preferably, the core-shell structure particles have a particle size of 0.080–0.120 μm; the primary particle size of the hydrophobic gaseous SiO2 is 0.007–0.012 μm; the outer diameter of the microcapsule catalyst is 2.0–3.0 μm, and the capsule wall thickness is 0.2–0.3 μm.

[0012] This invention also provides a method for preparing the above-mentioned CFEP-SiC composite material, comprising the following steps: (1) Preparation of modified resin system Bisphenol A type epoxy resin, alicyclic epoxy resin, and CTBN prepolymer were mixed in a reactor and heated to 80°C at a rate of 2-3°C / min. The mixture was then stirred at a constant temperature of 250 rpm for 45 min to obtain a homogeneous solution. While maintaining the system temperature at 80°C, the stirring speed was increased to 2500 rpm. α-SiC nanoparticles and β-SiC whiskers, surface-treated with a silane coupling agent, core-shell structured particles, hydrophobic fumed SiO2, and a dispersant were added sequentially. The mixture was then dispersed under high-speed shear for 45-60 min to obtain a suspension. DDS curing agent and microcapsule catalyst were added, and the mixture was gently stirred to obtain the final mixture. The final mixture was then degassed under vacuum to obtain the modified resin system. (2) Resin impregnation molding and curing T800 grade carbon fiber dry cloth is laid in the mold to form a fiber preform; the mold is closed, clamping force is applied, and the mold is preheated to 90-100℃; the mold cavity is evacuated to below -0.09MPa, and the modified resin system obtained in step (1) is injected into the mold cavity at 80-90℃ and 0.4-0.6MPa pressure to completely impregnate the fiber preform and obtain a green body; the green body is heated in the mold in a stepped heating program, first at 110-130℃ for 1-2h, and then at 170-190℃ for 2-3h to complete curing and obtain a cured part; (3) Finished product completed The cured component is cooled uniformly to below 60°C along with the mold, and then the mold is opened and the component is removed. The demolded component is then trimmed and drilled to obtain the CFEP-SiC composite material.

[0013] The present invention also provides a method for recycling the above-mentioned CFEP-SiC composite material, comprising the following steps: The CFEP-SiC composite material to be recycled was placed in an inert atmosphere and heated to 180℃~220℃ at a rate of 5~10℃ / min, and kept at this temperature for 2~4h to activate the microcapsule catalyst to degrade the resin matrix. The degraded resin matrix was separated from the carbon fiber and cleaned with an organic solvent. The cleaned carbon fiber was then dried to achieve carbon fiber recycling.

[0014] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: (1) This invention optimizes the formulation design and uses T800 grade carbon fiber as a high-strength and high-modulus skeleton; through the composite of CTBN prepolymer and core-shell structured particles, a micron / nano multi-scale toughening system is constructed, which significantly improves the fracture toughness and impact resistance of the material; through the combination of α-SiC nanoparticles and β-SiC whiskers, the hardness and wear resistance of the material are greatly improved; and innovatively, microcapsule catalysts are introduced, enabling traditional thermosetting composite materials to have the ability to be controlled degraded and recycled in a green manner.

[0015] (2) This invention employs an optimized resin transfer molding (RTM) process. This process uses a closed mold to ensure the molding and dimensions of the component; vacuum degassing before injection significantly reduces internal defects such as pores; and the segmented curing method ensures the overall quality and performance reliability of the component. The composite material prepared by this invention not only achieves an excellent combination of high hardness, high toughness, and recyclability, but also well meets the needs of the aerospace field. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The raw materials and their amounts used in the embodiments of the present invention are shown in Table 1; the raw material composition ratios of each embodiment are shown in Table 2.

[0020] Table 1. Raw materials used in the high-hardness, high-toughness, recyclable CFEP-SiC composite materials of the examples.

[0021] The silane coupling agent is γ-glycidyl etheroxypropyltrimethoxysilane; the dispersant is a polyether-siloxane block copolymer; the core-shell structured particles are rubber core-epoxy shell, with the core being a cross-linked styrene-butadiene rubber sphere with a particle size of 70 nm and the outer shell being an epoxy functionalized polymer with a thickness of 25 nm; the core of the microcapsule catalyst is a boron trifluoride ethylamine complex, and the capsule wall is a thermosensitive polyurethane; the outer diameter of the microcapsule catalyst is 2.5 μm, and the capsule wall thickness is 0.25 μm.

[0022] Table 2. Raw material composition ratios of high-hardness, high-toughness, and recyclable CFEP-SiC composite materials in each embodiment.

[0023] This invention provides a method for preparing CFEP-SiC composite materials, the process of which is as follows: Figure 1 As shown, it includes the following steps: (1) Preparation of modified resin system Bisphenol A type epoxy resin, alicyclic epoxy resin, and CTBN prepolymer were mixed in a reactor and heated to 80°C at a rate of 2-3°C / min. The mixture was then stirred at a constant temperature of 250 rpm for 45 min to obtain a homogeneous solution. While maintaining the system temperature at 80°C, the stirring speed was increased to 2500 rpm. α-SiC nanoparticles and β-SiC whiskers, surface-treated with a silane coupling agent, core-shell structured particles, hydrophobic fumed SiO2, and a dispersant were added sequentially. The mixture was then dispersed under high-speed shear for 45-60 min to obtain a suspension. The stirring speed was reduced to 300 rpm, and DDS curing agent and microcapsule catalyst were added. The mixture was gently stirred for 10-15 min to obtain the final mixture. The final mixture was then subjected to vacuum degassing for 45-60 min to obtain a modified resin system for injection molding. (2) Resin impregnation molding and curing T800 grade carbon fiber dry cloth is laid in the mold to form a fiber preform; the mold is closed, clamping force is applied, and the mold is preheated to 90-100℃; the mold cavity is evacuated to below -0.09MPa, and the modified resin system prepared in step (1) and kept at 80-90℃ is injected into the mold cavity from the injection port of the mold at a constant pressure of 0.4-0.6MPa until the resin completely impregnates the fiber preform to obtain a green body; the green body is heated in the mold in a stepped heating program, first kept at 110-130℃ for 1-2h to complete the initial curing; then the temperature is raised to 170-190℃ and kept for 2-3h to complete the curing, and the cured part is obtained. (3) Finished product completed The cured component is cooled uniformly to below 60°C along with the mold, and then the mold is opened and the component is removed. The demolded component is then precision machined by trimming and drilling to obtain the CFEP-SiC composite material.

[0024] The recycling method for the CFEP-SiC composite material includes the following steps: The CFEP-SiC composite material to be recycled was placed in an inert atmosphere and heated to 200°C at a rate of 8°C / min, and kept at that temperature for 3 hours to activate the microcapsule catalyst to degrade the resin matrix. The degraded resin matrix was separated from the carbon fibers using acetone and then washed. The washed carbon fibers were then dried to achieve the recycling of carbon fibers.

[0025] The preparation process parameters for each embodiment are shown in Table 3.

[0026] Table 3. Preparation process parameters of high-hardness and high-toughness CFEP-SiC composite materials in each embodiment.

[0027] Performance testing of CFEP-SiC composite materials: The fracture toughness of the composite material was tested using the single-sided pre-cracked beam method; hardness was tested using a Rockwell hardness tester; and the degradation rate of the matrix was verified by the thermal degradation-weighing method. To verify the independent effects of each key component, Comparative Examples 1 and 2 were obtained by removing only a single variable, using Example 2 as the baseline sample. Comparative Example 3 used a carbon fiber reinforced epoxy resin composite material prepared by a conventional method as the control sample; the conventional method refers to using an unmodified epoxy resin matrix, impregnating the carbon fiber reinforcement with resin through a conventional thermosetting composite molding process, and then curing it by heat. The properties of each product are shown in Table 4.

[0028] Table 4 Performance Indicators of Composite Materials

[0029] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention 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. Such 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 the present invention.

Claims

1. A high-hardness, high-toughness, recyclable CFEP-SiC composite material, characterized in that, By weight percentage, it includes the following raw materials: 55.7-58.5% T800 grade carbon fiber, 17.5-18.9% bisphenol A type epoxy resin, 7.0-7.6% alicyclic epoxy resin, 7.0-7.6% DDS curing agent, 0.9-1.1% CTBN prepolymer, 3.4-3.8% α-SiC nanoparticles, 1.6-2.0% β-SiC whiskers, 0.25-0.35% hydrophobic fumed SiO2, 0.35-0.45% silane coupling agent, 0.25-0.35% dispersant, 0.15-0.25% microencapsulated catalyst, and 1.6-2.0% core-shell structured particles.

2. The high-hardness, high-toughness, recyclable CFEP-SiC composite material according to claim 1, characterized in that, The silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

3. The high-hardness, high-toughness, recyclable CFEP-SiC composite material according to claim 1, characterized in that, The dispersant is a polyether-siloxane block copolymer.

4. The high-hardness, high-toughness, recyclable CFEP-SiC composite material according to claim 1, characterized in that, The core-shell structured particles are rubber core-epoxy shell, with the core being cross-linked styrene-butadiene rubber spheres with a particle size of 60-80 nm and the outer shell being an epoxy functionalized polymer with a thickness of 20-30 nm.

5. The high-hardness, high-toughness, recyclable CFEP-SiC composite material according to claim 1, characterized in that, The core of the microcapsule catalyst is a boron trifluoride ethylamine complex, and the capsule wall is a thermosensitive polyurethane.

6. The high-hardness, high-toughness, recyclable CFEP-SiC composite material according to claim 1, characterized in that, The T800 grade carbon fiber has a single filament diameter of 5.000–7.000 μm; the α-SiC nanoparticles have a particle size of 0.030–0.080 μm; and the β-SiC whiskers have a diameter of 0.1 μm and a length of 1.5–3.0 μm.

7. The high-hardness, high-toughness, recyclable CFEP-SiC composite material according to claim 1, characterized in that, The core-shell structured particles have a particle size of 0.080–0.120 μm; the primary particle size of the hydrophobic gaseous SiO2 is 0.007–0.012 μm; the outer diameter of the microcapsule catalyst is 2.0–3.0 μm, and the capsule wall thickness is 0.2–0.3 μm.

8. The method for preparing the CFEP-SiC composite material according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Preparation of modified resin system Bisphenol A type epoxy resin, alicyclic epoxy resin, and CTBN prepolymer were mixed in a reactor and heated to 80°C at a rate of 2-3°C / min. The mixture was then stirred at a constant temperature of 250 rpm for 45 min to obtain a homogeneous solution. While maintaining the system temperature at 80°C, the stirring speed was increased to 2500 rpm. α-SiC nanoparticles and β-SiC whiskers, surface-treated with a silane coupling agent, core-shell structured particles, hydrophobic fumed SiO2, and a dispersant were added sequentially. The mixture was then dispersed under high-speed shear for 45-60 min to obtain a suspension. DDS curing agent and microcapsule catalyst were added, and the mixture was gently stirred to obtain the final mixture. The final mixture was then degassed under vacuum to obtain the modified resin system. (2) Resin impregnation molding and curing T800 grade carbon fiber dry cloth is laid in the mold to form a fiber preform; Close the mold, apply clamping force, and preheat the mold to 90-100℃; evacuate the mold cavity to below -0.09MPa, and use resin transfer molding process to inject the modified resin system obtained in step (1) into the mold cavity at 80-90℃ and 0.4-0.6MPa pressure, completely impregnating the fiber preform to obtain a green body; heat the green body in the mold with a stepped heating program, first at 110-130℃ for 1-2h, then at 170-190℃ for 2-3h to complete curing and obtain a cured part; (3) Finished product completed The cured component is cooled uniformly to below 60°C along with the mold, and then the mold is opened and the component is removed. The demolded component is then trimmed and drilled to obtain the CFEP-SiC composite material.

9. The method for recycling the CFEP-SiC composite material according to any one of claims 1-7, characterized in that, Includes the following steps: The CFEP-SiC composite material to be recycled was placed in an inert atmosphere and heated to 180℃~220℃ at a rate of 5~10℃ / min, and kept at this temperature for 2~4h to activate the microcapsule catalyst to degrade the resin matrix. The degraded resin matrix was separated from the carbon fiber and cleaned with an organic solvent. The cleaned carbon fiber was then dried to achieve carbon fiber recycling.

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