Epoxy resin-based composite material and preparation method thereof

Abstract

The invention relates to the technical field of epoxy resin composite materials, in particular to an epoxy resin-based composite material and a preparation method thereof. The epoxy resin-based composite material comprises modified carbon fibers and an epoxy resin base material impregnated on a modified carbon fiber matrix, and the epoxy resin base material comprises the following raw materials in parts by weight: 80-100 parts of epoxy resin, 4-18 parts of a toughening elastomer, 24-45 parts of a curing agent and 1-3 parts of an accelerant. The carbon fibers are subjected to surface grafting hyperbranched molecular modification, so that the interface action between the modified carbon fibers and an epoxy resin matrix can be remarkably enhanced, and meanwhile, the high strength and high temperature-resistant stability of the carbon fibers are utilized, so that the epoxy resin-based composite material has good toughening, reinforcing and temperature resistance improving effects.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy resin composite materials, and in particular to an epoxy resin-based composite material and a preparation method thereof. Background Art

[0002] Epoxy resin is the most widely used thermosetting resin, which can be used as structural adhesives, coatings and composite matrix. However, for pure epoxy resin, due to the highly cross-linked network structure, it is brittle and usually exhibits low conductivity and high flammability. For this reason, adding fillers to epoxy resin is an effective way to enhance its mechanical strength, thermal stability, wear resistance, flame retardancy and thermal conductivity. Among them, carbon nanomaterials such as carbon nanotubes, carbon nanofibers and graphene are not easy to enhance the strength, thermal conductivity, low density and dielectric properties of composite materials compared to metal fillers, while not easy to lose their original mechanical properties and thermal properties. The carbon fiber reinforced resin-based composite materials obtained by this are widely used in aerospace, transportation and new energy fields due to their light weight, high strength, good corrosion resistance and high temperature resistance. However, for now, due to the smoothness of carbon fiber and its non-polar surface, it has poor bonding with resin and low mechanical properties, that is, the weak interaction between carbon fiber and resin matrix and the large modulus difference easily make the composite material as a whole have serious interface problems, which also limits the production and further development and application of such carbon fiber reinforced resin-based composite materials. Summary of the invention

[0003] The purpose of the present invention is to provide an epoxy resin-based composite material and a preparation method thereof in order to solve the above-mentioned deficiencies in the prior art.

[0004] The objective of the present invention is achieved through the following technical scheme: The present invention provides an epoxy resin-based composite material, comprising a modified carbon fiber and an epoxy resin base material impregnated on the modified carbon fiber matrix, wherein the epoxy resin base material comprises the following raw materials in parts by weight: 80-100 parts of epoxy resin, 4-18 parts of toughening elastomer, 24-45 parts of curing agent, and 1-3 parts of accelerator.

[0005] Furthermore, based on the total mass of the epoxy resin-based composite material, the content of the epoxy resin material is 35-60wt%.

[0006] Furthermore, the preparation method of the modified carbon fiber comprises the following steps: (1) mixing KH-550, ethanol and water evenly into a modified mixed solution, adding carbon fiber to the modified mixed solution, heating to 50-55° C. and stirring for 4-6 hours, washing, filtering and drying to obtain the initially treated carbon fiber;

[0007] (2) placing the initially treated carbon fiber obtained in step (1) in a reactor, adding tetrahydrophthalic anhydride, stirring evenly and heating until completely dissolved, then adding triethanolamine and p-toluenesulfonic acid and mixing thoroughly, stirring and reacting at 110-120° C. for 6-8 hours, then adding diethylenetriamine and continuing the reaction for 8-10 hours, thereby obtaining the modified carbon fiber.

[0008] Furthermore, in step (1), the carbon fiber refers to a desizing carbon fiber having active groups such as hydroxyl and carboxyl groups on the surface after gas phase oxidation, liquid phase oxidation or plasma treatment. After the desizing carbon fiber is oxidized, more active groups such as hydroxyl groups can be exposed on the surface of the carbon fiber, which is beneficial to improve the interface bonding strength between the carbon fiber and the matrix material, thereby improving the performance of the composite material.

[0009] Furthermore, in step (1), the mass ratio of KH-550, ethanol and water is 8-10:1:1, and the mass ratio of carbon fiber to modified mixed liquid is 1:4-5; in step (2), based on 1g of initially treated carbon fiber, the molar amount of tetrahydrophthalic anhydride is 12-16mmol, and the molar ratio of triethanolamine to tetrahydrophthalic anhydride is 1.01-1.1:1.

[0010] Furthermore, the epoxy resin is bisphenol A epoxy resin.

[0011] Furthermore, the preparation method of the toughened elastomer comprises the following steps: (1) placing hydrogenated hydroxyl-terminated polybutadiene and hydroxyl-terminated polybutadiene diol in a reaction container and stirring them uniformly, then adding toluene diisocyanate, an organic tin catalyst and dichloromethane thereto, dispersing them uniformly under ultrasonic conditions, and stirring at room temperature for 2-3 hours; (2) adding polyisobutylene succinic anhydride and an antioxidant to the mixture obtained in step (1), heating and stirring until the solvent evaporates to obtain a homogeneous mixed liquid, and finally curing by vacuum heating to obtain the toughened elastomer.

[0012] Furthermore, in step (1), the molar ratio of the hydroxyl groups contained in the hydrogenated hydroxyl-terminated polybutadiene to the hydroxyl-terminated polybutadiene diol is 1:1.

[0013] Furthermore, the epoxy resin base material also includes 15-30 parts of bisphenol E cyanate and 0.1-1 part of an organic tin catalyst.

[0014] Furthermore, the curing agent is an amide curing agent, and the preparation method of the amide curing agent comprises the following steps: adding diethyl terephthalate, diethanolamine, sodium methoxide and dichloromethane to a reactor in sequence, heating and refluxing to react, filtering to obtain a white solid, then dissolving the solid in methanol, adding acetone dropwise while heating, cooling naturally, filtering and drying to obtain the amide curing agent.

[0015] Furthermore, the mass ratio of diethyl terephthalate, diethanolamine and sodium methoxide is 1-1.1:1:0.75-0.8.

[0016] Furthermore, the accelerator is at least one of 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-phenyl-4-methylimidazole.

[0017] The present invention also provides a method for preparing the above-mentioned epoxy resin-based composite material, comprising the following steps: taking epoxy resin into a reactor, adding modified carbon fiber, heating and stirring until there are no bubbles, then adding a toughening elastomer and continuing to stir, and then adding a curing agent and an accelerator for curing to obtain the epoxy resin-based composite material.

[0018] The beneficial effects of the present invention are as follows: (1) The epoxy resin-based composite material obtained by impregnating the modified carbon fiber into an epoxy resin matrix and then curing the epoxy resin-based composite material has excellent strength, toughness and heat resistance. In particular, by modifying the carbon fiber by surface grafting hyperbranched molecules, the carbon fiber can be chemically bonded with the epoxy resin matrix, thereby enhancing the interface performance between the carbon fiber and the epoxy resin matrix, thereby helping to improve the strength, toughness and heat resistance of the epoxy resin-based composite material.

[0019] (2) By introducing a toughening elastomer into the epoxy resin base material, the intermolecular force between the polar groups such as carboxyl and hydroxyl groups on the surface of the toughening elastomer and the epoxy resin is generated, which helps to improve the mechanical properties of the epoxy resin base material and improve the brittleness problem that is common in epoxy resins.

[0020] (3) The amide curing agent prepared by the present invention can be evenly dispersed in the epoxy resin matrix, and can be better controlled to smoothly control the curing reaction process when combined with the accelerator, thereby reducing the internal stress of the system. In addition, the cross-linked structure of the cured epoxy resin also has certain flexible segments, which helps to maintain the toughness and impact resistance of the epoxy resin-based composite material. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0022] It should be noted that, in the following embodiments and comparative examples of the present invention, the carbon fibers are calcined at 550°C to remove the sizing agent on the surface of the carbon fibers before use, and then the fibers are subjected to gas phase oxidation in an air atmosphere at 330°C. However, the operation here is not a limitation on the pretreatment of the carbon fibers. The oxidation treatment of the carbon fibers after desizing can also be carried out by the known liquid phase oxidation or plasma oxidation methods, which can expose more active groups such as hydroxyl groups on the surface of the carbon fibers, which is beneficial to improve the interfacial bonding between the carbon fibers and the matrix material.

[0023] Example 1

[0024] The present embodiment provides an epoxy resin-based composite material, including modified carbon fiber and an epoxy resin base material impregnated on the modified carbon fiber matrix, wherein the epoxy resin base material includes the following raw materials in parts by weight: 85 parts of epoxy resin, 10 parts of toughening elastomer, 30 parts of curing agent, and 2 parts of accelerator.

[0025] Furthermore, based on the total mass of the epoxy resin-based composite material, the content of the epoxy resin material is 45wt%.

[0026] Furthermore, the preparation method of the modified carbon fiber comprises the following steps: (1) KH-550, ethanol and water are uniformly mixed to form a modified mixed solution, carbon fiber is added to the modified mixed solution, heated to 50° C. and stirred for 5 h, and the primary treated carbon fiber is obtained by washing, filtering and drying;

[0027] (2) The initially treated carbon fiber obtained in step (1) is placed in a reactor, tetrahydrophthalic anhydride is added, stirred evenly and heated until completely dissolved, triethanolamine and 1 wt% of toluenesulfonic acid are added and mixed thoroughly, and the mixture is stirred and reacted at 110° C. for 6 hours, and then diethylenetriamine is added and the reaction is continued for 8 hours to obtain the modified carbon fiber.

[0028] Furthermore, in step (1), the mass ratio of KH-550, ethanol and water is 9:1:1, and the mass ratio of carbon fiber to modified mixed liquid is 1:4.5; in step (2), based on 1g of initially treated carbon fiber, the molar amount of tetrahydrophthalic anhydride is 14mmol, and the molar ratio of triethanolamine to tetrahydrophthalic anhydride is 1.05:1.

[0029] Furthermore, the epoxy resin is epoxy resin E44.

[0030] Furthermore, the preparation method of the toughened elastomer comprises the following steps: (1) placing hydrogenated hydroxyl-terminated polybutadiene (Mn=2000) and hydroxyl-terminated polybutadiene diol (Mn=3000) in a reaction container and stirring them evenly, then adding 2.5wt% toluene diisocyanate, 1wt% organotin catalyst T-12 and a small amount of dichloromethane thereto, dispersing them evenly under ultrasonic conditions, and stirring at room temperature for 3h; (2) adding 2wt% polyisobutylene succinic anhydride and 1wt% antioxidant 264 to the mixture obtained in step (1), heating and constant temperature at 80°C, stirring until the solvent evaporates to obtain a homogeneous mixed liquid, and finally curing by vacuum heating to obtain the toughened elastomer.

[0031] Furthermore, in step (1), the molar ratio of the hydroxyl groups contained in the hydrogenated hydroxyl-terminated polybutadiene to the hydroxyl-terminated polybutadiene diol is 1:1.

[0032] Furthermore, the curing agent is an amide curing agent, and the preparation method of the amide curing agent comprises the following steps: adding diethyl terephthalate, diethanolamine, sodium methoxide and dichloromethane to a reactor in sequence, heating and refluxing to react overnight, filtering to obtain a white solid, and then dissolving it in methanol at a mass volume ratio of 1:20, while heating to maintain 60°C while adding acetone dropwise (the volume ratio of acetone to methanol is 1:1), and after natural cooling, filtering and drying to obtain the amide curing agent.

[0033] Furthermore, the mass ratio of diethyl terephthalate, diethanolamine and sodium methoxide is 1.05:1:0.78, and the mass volume ratio of dichloromethane to diethanolamine is 25:1.

[0034] Furthermore, the accelerator is 2-methylimidazole.

[0035] The preparation method of the above-mentioned epoxy resin-based composite material in this embodiment includes the following steps: taking epoxy resin in a reactor, adding modified carbon fiber, heating and stirring until there are no bubbles, then adding toughening elastomer and continuing to stir, and then adding curing agent and accelerator for curing to obtain the epoxy resin-based composite material.

[0036] Example 2

[0037] The present embodiment provides an epoxy resin-based composite material, including modified carbon fiber and an epoxy resin base material impregnated on the modified carbon fiber matrix, wherein the epoxy resin base material includes the following raw materials in parts by weight: 90 parts of epoxy resin, 14 parts of toughening elastomer, 35 parts of curing agent, and 3 parts of accelerator.

[0038] Furthermore, based on the total mass of the epoxy resin-based composite material, the content of the epoxy resin material is 50 wt %.

[0039] Furthermore, the preparation method of the modified carbon fiber comprises the following steps: (1) KH-550, ethanol and water are uniformly mixed to form a modified mixed solution, carbon fiber is added to the modified mixed solution, heated to 55° C. and stirred for 5 h, and the primary treated carbon fiber is obtained by washing, filtering and drying;

[0040] (2) placing the initially treated carbon fiber obtained in step (1) in a reactor, adding tetrahydrophthalic anhydride, stirring evenly and heating until completely dissolved, then adding triethanolamine and p-toluenesulfonic acid and mixing thoroughly, stirring and reacting at 120° C. for 6 hours, and then adding diethylenetriamine and continuing the reaction for 9 hours to obtain the modified carbon fiber.

[0041] Furthermore, in step (1), the mass ratio of KH-550, ethanol and water is 9:1:1, and the mass ratio of carbon fiber to modified mixed liquid is 1:4.5; in step (2), based on 1g of initially treated carbon fiber, the molar amount of tetrahydrophthalic anhydride is 15mmol, and the molar ratio of triethanolamine to tetrahydrophthalic anhydride is 1.05:1.

[0042] Furthermore, the epoxy resin is epoxy resin E51.

[0043] Furthermore, the epoxy resin base material also includes 20 parts of bisphenol E cyanate and 0.5 parts of dibutyltin dilaurate.

[0044] Furthermore, the preparation method of the toughened elastomer comprises the following steps: (1) placing hydrogenated hydroxyl-terminated polybutadiene (Mn=2000) and hydroxyl-terminated polybutadiene diol (Mn=3000) in a reaction container and stirring them evenly, then adding 2.5wt% toluene diisocyanate, 1wt% organotin catalyst T-12 and a small amount of dichloromethane thereto, dispersing them evenly under ultrasonic conditions, and stirring at room temperature for 3h; (2) adding 2wt% polyisobutylene succinic anhydride and 1wt% antioxidant 264 to the mixture obtained in step (1), heating and constant temperature at 80°C, stirring until the solvent evaporates to obtain a homogeneous mixed liquid, and finally curing by vacuum heating to obtain the toughened elastomer.

[0045] Furthermore, in step (1), the molar ratio of the hydroxyl groups contained in the hydrogenated hydroxyl-terminated polybutadiene to the hydroxyl-terminated polybutadiene diol is 1:1.

[0046] Furthermore, the curing agent is an amide curing agent, and the preparation method of the amide curing agent comprises the following steps: adding diethyl terephthalate, diethanolamine, sodium methoxide and dichloromethane to a reactor in sequence, heating and refluxing to react overnight, filtering to obtain a white solid, and then dissolving it in methanol at a mass volume ratio of 1:20, while heating to maintain 60°C while adding acetone dropwise (the volume ratio of acetone to methanol is 1:1), and after natural cooling, filtering and drying to obtain the amide curing agent.

[0047] Furthermore, the mass ratio of diethyl terephthalate, diethanolamine and sodium methoxide is 1.05:1:0.78, and the mass volume ratio of dichloromethane to diethanolamine is 25:1.

[0048] Furthermore, the promoter is 2-ethyl-4-methylimidazole.

[0049] The preparation method of the above-mentioned epoxy resin-based composite material in this embodiment includes the following steps: taking epoxy resin and bisphenol E type cyanate ester and mixing them evenly in a 60°C reactor, then adding dibutyltin dilaurate and mixing them evenly, heating to 90°C and stirring for 1 hour, then adding modified carbon fiber and stirring until there are no bubbles, then adding toughening elastomer and continuing to stir, and then adding curing agent and accelerator for curing to obtain the epoxy resin-based composite material.

[0050] Example 3

[0051] The present embodiment provides an epoxy resin-based composite material, including modified carbon fiber and an epoxy resin base material impregnated on the modified carbon fiber matrix, wherein the epoxy resin base material includes the following raw materials in parts by weight: 95 parts of epoxy resin, 16 parts of toughening elastomer, 40 parts of curing agent, and 3 parts of accelerator.

[0052] Furthermore, based on the total mass of the epoxy resin-based composite material, the content of the epoxy resin material is 55 wt %.

[0053] Furthermore, the preparation method of the modified carbon fiber comprises the following steps: (1) KH-550, ethanol and water are uniformly mixed to form a modified mixed solution, carbon fiber is added to the modified mixed solution, heated to 55° C. and stirred for 6 hours, and the primary treated carbon fiber is obtained by washing, filtering and drying;

[0054] (2) placing the initially treated carbon fiber obtained in step (1) in a reactor, adding tetrahydrophthalic anhydride, stirring evenly and heating until completely dissolved, then adding triethanolamine and p-toluenesulfonic acid and mixing thoroughly, stirring and reacting at 120° C. for 7 hours, and then adding diethylenetriamine and continuing the reaction for 9 hours to obtain the modified carbon fiber.

[0055] Furthermore, in step (1), the mass ratio of KH-550, ethanol and water is 9:1:1, and the mass ratio of carbon fiber to modified mixed liquid is 1:4.5; in step (2), based on 1g of initially treated carbon fiber, the molar amount of tetrahydrophthalic anhydride is 15mmol, and the molar ratio of triethanolamine to tetrahydrophthalic anhydride is 1.05:1.

[0056] Furthermore, the epoxy resin is epoxy resin E51.

[0057] The epoxy resin base material also includes 25 parts of bisphenol E cyanate and 0.6 parts of an organic tin catalyst.

[0058] Furthermore, the preparation method of the toughened elastomer comprises the following steps: (1) placing hydrogenated hydroxyl-terminated polybutadiene (Mn=2000) and hydroxyl-terminated polybutadiene diol (Mn=3000) in a reaction container and stirring them evenly, then adding 2.5wt% toluene diisocyanate, 1wt% organotin catalyst T-12 and a small amount of dichloromethane thereto, dispersing them evenly under ultrasonic conditions, and stirring at room temperature for 3h; (2) adding 2wt% polyisobutylene succinic anhydride and 1wt% antioxidant 264 to the mixture obtained in step (1), heating and constant temperature at 80°C, stirring until the solvent evaporates to obtain a homogeneous mixed liquid, and finally curing by vacuum heating to obtain the toughened elastomer.

[0059] Furthermore, in step (1), the molar ratio of the hydroxyl groups contained in the hydrogenated hydroxyl-terminated polybutadiene to the hydroxyl-terminated polybutadiene diol is 1:1.

[0060] Furthermore, the curing agent is an amide curing agent, and the preparation method of the amide curing agent comprises the following steps: adding diethyl terephthalate, diethanolamine, sodium methoxide and dichloromethane to a reactor in sequence, heating and refluxing to react overnight, filtering to obtain a white solid, and then dissolving it in methanol at a mass volume ratio of 1:20, while heating to maintain 60°C while adding acetone dropwise (the volume ratio of acetone to methanol is 1:1), and after natural cooling, filtering and drying to obtain the amide curing agent.

[0061] Furthermore, the mass ratio of diethyl terephthalate, diethanolamine and sodium methoxide is 1.05:1:0.78.

[0062] Furthermore, the accelerator is 2-phenyl-4-methylimidazole.

[0063] The preparation method of the above-mentioned epoxy resin-based composite material in this embodiment includes the following steps: taking epoxy resin and bisphenol E type cyanate ester and mixing them evenly in a 60°C reactor, then adding dibutyltin dilaurate and mixing them evenly, heating to 90°C and stirring for 1 hour, then adding modified carbon fiber and stirring until there are no bubbles, then adding toughening elastomer and continuing to stir, and then adding curing agent and accelerator for curing to obtain the epoxy resin-based composite material.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that this comparative example uses desizing carbon fiber to replace the modified carbon fiber in Example 1.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 1 is that the preparation method of modified carbon fiber in this comparative example includes the following steps: KH-550, ethanol and water are evenly mixed to form a modified mixed liquid, carbon fiber is added to the modified mixed liquid, heated to 50°C and stirred for 5h, and the modified carbon fiber is obtained by washing, filtering and drying.

[0068] The mass ratio of KH-550, ethanol and water is 9:1:1, and the mass ratio of carbon fiber to modified mixed liquid is 1:4.5.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 1 is that the toughening elastomer in Example 1 is not added to this comparative example.

[0071] Comparative Example 4

[0072] The difference between this comparative example and Example 1 is that this comparative example uses THEA curing agent instead of the curing agent in Example 1.

[0073] In the present invention, the epoxy resin-based composite materials prepared in the above-mentioned Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests, including tensile strength, flexural strength, elongation at break, impact strength and heat resistance tests. Among them, tensile strength, flexural strength, elongation at break and impact strength were tested using GB / T 2567-2008; the heat resistance of the epoxy resin-based composite materials was tested using thermogravimetric analysis, with a test temperature of 25-800°C, a heating rate of 10°C / min, and a test atmosphere of nitrogen and air. The results are shown in the following table.

[0074]

[0075]

[0076] It can be seen from the data in the above table that the epoxy resin-based composite materials obtained in Examples 1-3 of the present invention have excellent comprehensive mechanical properties and good heat resistance. Among them, the tensile strength of the epoxy resin-based composite materials is between 76.7 and 80.9 MPa, the flexural strength is between 118.3 and 126.9 MPa, the elongation at break is between 6.08 and 8.63%, and the impact strength is between 5.04 and 6.97 kJ / ㎡. At the same time, the glass transition temperature of the epoxy resin-based composite materials obtained by the present invention is greater than 180°C, indicating that it has good heat resistance. Further, the results of Comparative Examples 1-2 and Example 1 are compared to show that the present invention, by modifying the carbon fiber, grafts a hyperbranched molecule with an amino terminal on the surface of the carbon fiber, so that it is chemically bonded to the epoxy resin matrix, and enhances the interface performance between the carbon fiber and the epoxy resin matrix; at the same time, the hyperbranched molecule has a flexible molecular chain, and the lightweight, high strength, high thermal conductivity and temperature resistance of the carbon fiber also play a role in toughening and reinforcing the epoxy resin-based composite material and improving its thermal stability. By comparing the results of Comparative Example 3 with those of Example 1, it can be seen that by adding a toughening elastomer to the epoxy resin base material, it has a significant effect on improving the mechanical properties of the epoxy resin base material. By comparing the results of Comparative Example 4 with those of Comparative Example 1, it can be seen that the amide curing agent prepared by the present invention is matched with an accelerator, and can be evenly dispersed in the epoxy resin matrix, so that it fully reacts with the epoxy resin to form a uniform and stable cross-linked network, and the cured epoxy resin cross-linked structure also has a certain flexible segment, which helps to improve the mechanical properties of the epoxy resin-based composite material.

[0077] The above specific embodiments are further explanations of the technical solutions and beneficial effects of the present invention, and are not limitations of the implementation methods. For those skilled in the art, any obvious replacements that do not depart from the concept of the present invention are within the protection scope of the present invention.

Claims

1. An epoxy resin-based composite material, characterized in that: The invention comprises modified carbon fiber and epoxy resin base material impregnated on the modified carbon fiber matrix. The epoxy resin base material comprises the following raw materials in parts by weight: 80-100 parts of epoxy resin, 4-18 parts of toughening elastomer, 24-45 parts of curing agent and 1-3 parts of accelerator.

2. The epoxy resin-based composite material according to claim 1, characterized in that: Based on the total mass of the epoxy resin-based composite material, the content of the epoxy resin material is 35-60wt%.

3. The epoxy resin-based composite material according to claim 1, characterized in that: The preparation method of the modified carbon fiber comprises the following steps: (1) KH-550, ethanol and water are mixed uniformly to form a modified mixed solution, carbon fiber is added to the modified mixed solution, heated to 50-55° C. and stirred for 4-6 hours, and the primary treated carbon fiber is obtained by washing, filtering and drying; (2) placing the initially treated carbon fiber obtained in step (1) in a reactor, adding tetrahydrophthalic anhydride, stirring evenly and heating until completely dissolved, then adding triethanolamine and p-toluenesulfonic acid and mixing thoroughly, stirring and reacting at 110-120° C. for 6-8 hours, then adding diethylenetriamine and continuing the reaction for 8-10 hours, thereby obtaining the modified carbon fiber.

4. The epoxy resin-based composite material according to claim 3, characterized in that: In step (1), the carbon fiber refers to a desized carbon fiber having active groups such as hydroxyl groups and carboxyl groups on its surface after gas phase oxidation, liquid phase oxidation or plasma treatment.

5. The epoxy resin-based composite material according to claim 1, characterized in that: The epoxy resin is bisphenol A type epoxy resin.

6. The epoxy resin-based composite material according to claim 1, characterized in that: The preparation method of the toughened elastomer comprises the following steps: (1) placing hydrogenated hydroxyl-terminated polybutadiene and hydroxyl-terminated polybutadiene diol in a reaction container and stirring them uniformly, then adding toluene diisocyanate, an organic tin catalyst and dichloromethane thereto, dispersing them uniformly under ultrasonic conditions, and stirring them at room temperature for 2-3 hours; (2) adding polyisobutylene succinic anhydride and an antioxidant to the mixture obtained in step (1), heating and stirring until the solvent evaporates to obtain a homogeneous mixed liquid, and finally curing by vacuum heating to obtain the toughened elastomer.

7. The epoxy resin-based composite material according to claim 1, characterized in that: The epoxy resin base material also includes 15-30 parts of bisphenol E cyanate and 0.1-1 parts of an organic tin catalyst.

8. The epoxy resin-based composite material according to claim 1, characterized in that: The curing agent is an amide curing agent.

9. The epoxy resin-based composite material according to claim 1, characterized in that: The accelerator is at least one of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenyl-4-methylimidazole.

10. The method for preparing the epoxy resin-based composite material according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: putting epoxy resin in a reactor, adding modified carbon fiber, heating and stirring until there is no bubble, then adding toughening elastomer and continuing stirring, and then adding curing agent and accelerator for curing to obtain the epoxy resin-based composite material.

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