High-toughness epoxy resin-based carbon fiber prepreg and preparation method thereof

Abstract

The invention relates to the technical field of polymer composite materials, in particular to a high-toughness epoxy resin-based carbon fiber prepreg and a preparation method thereof. The prepreg is prepared from carbon fibers, synergistically modified epoxy resin, 2, 6-dihydroxytriptycene, a curing agent, an accelerant, a thermoplastic toughening agent, a rheology modifier and nano filler. According to the invention, hydroxypropyl-beta-cyclodextrin and 1-adamantane methylamine form a host-guest inclusion structure, 3-aminophenylboronic acid and tannic acid form a dynamic borate bond, octa (glycidyl ether propyl) silsesquioxane is introduced to construct a cage-shaped rigid node, and bisphenol F type epoxy resin and tetrafunctional glycidyl amine type epoxy resin are subjected to synergistic modification so as to obtain the epoxy resin. And constructing a three-dimensional dynamic cross-linked network structure to obtain the synergistically modified epoxy resin. Through the synergistic effect of multiple structures and the regulation and control of 2, 6-dihydroxytriptycene on an interface, the interlaminar shear strength, impact strength and fracture toughness of the prepreg can be remarkably improved, and meanwhile, the interface bonding performance between the carbon fibers and a resin matrix is enhanced.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to a high-toughness epoxy resin-based carbon fiber prepreg and its preparation method. Background Technology

[0002] Carbon fiber reinforced epoxy resin composites are widely used in aerospace, wind turbine blades, rail transportation, automotive lightweighting, and high-end equipment manufacturing due to their high specific strength, high specific modulus, good corrosion resistance, and excellent dimensional stability. Carbon fiber prepreg, as an important intermediate material in the preparation of carbon fiber composites, depends to a large extent on the structural properties of the epoxy resin matrix and the interfacial bonding state between the carbon fibers and the resin.

[0003] Currently, commonly used epoxy resin-based carbon fiber prepreg systems mostly use bisphenol A or bisphenol F epoxy resins as the matrix resin, which form a highly cross-linked three-dimensional network structure after curing with a curing agent. Although this structure can endow the composite material with high strength and modulus, the high cross-linking density and limited molecular chain mobility of the epoxy resin after curing make the material exhibit obvious brittle characteristics. Under impact or stress concentration, cracks are easily generated and propagated rapidly, leading to problems such as interlaminar delamination and interfacial failure, which seriously affect the reliability and durability of the composite material.

[0004] To improve the toughness of epoxy resin systems, existing technologies typically employ methods such as rubber toughening, thermoplastic resin toughening, or nanoparticle modification. However, rubber toughening often reduces the material's heat resistance and modulus, while thermoplastic resin toughening tends to increase the system viscosity, affecting the wetting properties and process stability of the prepreg. Although nanofillers can improve mechanical properties to some extent, their poor dispersibility and limited interfacial bonding ability limit their toughening effect.

[0005] Traditional modification methods often focus on toughening a single structure or mechanism, making it difficult to simultaneously address the material's toughness, interfacial bonding strength, and structural stability. Therefore, developing a modified epoxy resin system that can significantly improve toughness while maintaining the high strength and high modulus of the epoxy resin system, and improve the interfacial bonding performance between carbon fibers and resin, thereby preparing high-performance carbon fiber prepregs, is of significant research importance and application value. Summary of the Invention

[0006] In order to overcome the problems of insufficient toughness, easy crack propagation, and limited interfacial bonding strength between carbon fiber and resin in existing epoxy resin-based carbon fiber prepregs, the present invention aims to provide a high-toughness epoxy resin-based carbon fiber prepreg and its preparation method. This invention provides a high-toughness epoxy resin-based carbon fiber prepreg, comprising carbon fiber, synergistically modified epoxy resin, 2,6-dihydroxytriptene, curing agent, accelerator, thermoplastic toughening agent, rheology modifier, and nanofiller. The prepreg is prepared by forming a host-guest inclusion structure with hydroxypropyl-β-cyclodextrin and 1-adamantanemethylamine, and by forming dynamic borate ester bonds with 3-aminophenylboronic acid and tannic acid. Simultaneously, octa(glycidyl ether propyl)silsesquioxane is introduced to construct cage-like rigid nodes, synergistically modifying bisphenol F type epoxy resin and tetrafunctional glycidylamine type epoxy resin. This constructs a three-dimensional dynamic crosslinked network structure with a host-guest slip structure, dynamic covalent bonds, and cage-like rigid nodes, thereby obtaining a synergistically modified epoxy resin. This modified epoxy resin is then combined with carbon fiber and other additives to prepare the high-toughness epoxy resin-based carbon fiber prepreg. This invention constructs a three-dimensional dynamic crosslinking network with synergistic effects of host-guest inclusion structure, dynamic borate ester bonds, and cage-like silsesquioxane nodes, and introduces 2,6-dihydroxytriptene for interface regulation, which can significantly improve the toughness and interfacial bonding performance of epoxy resin-based carbon fiber prepregs while maintaining the strength and structural stability of the material.

[0007] The objective of this invention can be achieved through the following technical solutions: A high-toughness epoxy resin-based carbon fiber prepreg comprises the following raw materials in parts by weight: 80-150 parts carbon fiber, 70-100 parts synergistically modified epoxy resin, 0.3-4 parts 2,6-dihydroxytriptene, 20-45 parts curing agent, 0.2-2 parts accelerator, 2-12 parts thermoplastic toughening agent, 0.2-3 parts rheology modifier, and 0.5-5 parts nanofiller; the synergistically modified epoxy resin is obtained by forming a host-guest inclusion structure with hydroxypropyl-β-cyclodextrin and 1-adamantanemethylamine, and forming dynamic borate ester bonds with tannic acid through 3-aminophenylboronic acid, while introducing octa(glycidyl ether propyl)silsesquioxane to construct cage-like rigid nodes, thereby synergistically modifying bisphenol F type epoxy resin and tetrafunctional glycidylamine type epoxy resin to construct a three-dimensional dynamic crosslinking network.

[0008] Optionally, the synergistically modified epoxy resin comprises the following raw materials in parts by weight: 35-60 parts of bisphenol F type epoxy resin, 10-30 parts of tetrafunctional glycidylamine type epoxy resin, 0.5-4 parts of hydroxypropyl-β-cyclodextrin, 0.2-2 parts of 1-adamantanemethylamine, 0.3-3 parts of 3-aminophenylboronic acid, 0.3-3 parts of tannic acid, 0.5-5 parts of octa(glycidyl ether propyl)silsesquioxane, and 0.3-3 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0009] Optionally, the preparation method of the synergistically modified epoxy resin includes the following steps: (1) Bisphenol F type epoxy resin, tetrafunctional glycidylamine type epoxy resin, hydroxypropyl-β-cyclodextrin and 1-adamantane methylamine are mixed and stirred to form a host-guest inclusion structure between hydroxypropyl-β-cyclodextrin and 1-adamantane methylamine, thereby obtaining a host-guest structure modified epoxy resin intermediate. (2) Add 3-aminophenylboronic acid and tannic acid to the host-guest structure modified epoxy resin intermediate and react them to form a dynamic borate ester structure, thereby obtaining a dynamic borate ester network modified epoxy resin intermediate. (3) Add octa(glycidyl ether propyl) silsesquioxane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane to the dynamic borate ester network modified epoxy resin intermediate and react to obtain a synergistically modified epoxy resin.

[0010] Optionally, the reaction conditions in step (1) are as follows: the reaction is carried out at 65-85°C under nitrogen protection, the stirring speed is 300-500 rpm, and the reaction time is 1-2 h.

[0011] Optionally, the reaction conditions in step (2) are as follows: the reaction is carried out at 70-90°C, the pH of the system is 7.5-9.0, the stirring speed is 300-600 rpm, and the reaction time is 1.5-3 h.

[0012] Optionally, the reaction conditions in step (3) are as follows: the reaction is carried out at 75-95°C, the stirring speed is 400-700 rpm, and the reaction time is 1-3 h.

[0013] Optionally, the curing agent is a mixture of 4,4'-diaminodiphenyl sulfone and diaminodiphenylmethane in a mass ratio of (3-8):(2-5); the accelerator is a mixture of 2-methylimidazole and 2-ethyl-4-methylimidazole in a mass ratio of (1-4):(1-3); the thermoplastic toughening agent is a mixture of polyethersulfone and polyamide imide in a mass ratio of (4-10):(1-4); the rheology modifier is a mixture of fumed silica and polyamide wax in a mass ratio of (2-6):(1-3); and the nanofiller is a mixture of nano-silica and nano-alumina in a mass ratio of (3-8):(1-4).

[0014] Optionally, a method for preparing a high-toughness epoxy resin-based carbon fiber prepreg includes the following steps: S1, the synergistic modified epoxy resin, 2,6-dihydroxytriptene, thermoplastic toughening agent, rheology modifier and nanofiller are mixed and stirred to disperse to obtain a modified epoxy resin matrix mixture; S2, add curing agent and accelerator to the modified epoxy resin matrix mixture and mix to obtain a prepreg resin system; S3 involves impregnating carbon fibers with a prepreg resin system to ensure uniform resin impregnation. After adjusting the resin content by scraping, a pre-curing treatment is performed to obtain a high-toughness epoxy resin-based carbon fiber prepreg.

[0015] Optionally, the reaction conditions for step S1 are: stirring and dispersing at 60–80°C, stirring speed of 400–700 rpm, and dispersion time of 0.5–1.5 h; and the reaction conditions for step S2 are: mixing and stirring at 50–70°C, stirring speed of 300–600 rpm, and mixing time of 0.5–1 h.

[0016] Optionally, the reaction conditions in step S3 are as follows: the impregnation temperature of the carbon fiber in the resin system is 50-70°C, the impregnation time is 3-10 min, the pre-curing temperature is 80-110°C, and the pre-curing time is 5-20 min.

[0017] The beneficial effects of this invention are: This invention constructs a host-guest inclusion dynamic crosslinking structure using hydroxypropyl-β-cyclodextrin and 1-adamantanemethylamine, enabling the epoxy resin network to undergo molecular-scale slip and energy dissipation under stress, thereby effectively inhibiting rapid crack propagation. Simultaneously, the formation of dynamic borate ester bonds between 3-aminophenylboronic acid and tannic acid allows the resin system to undergo reversible dynamic rearrangement under external forces, improving the material's resistance to crack propagation. Furthermore, octa(glycidyl ether propyl)silsesquioxane is introduced as a cage-like rigid nanonode embedded in the epoxy crosslinking network, enhancing the stability of the crosslinking structure while strengthening the rigidity and heat resistance of the resin matrix. The addition of 2,6-dihydroxytriptene, with its rigid three-dimensional aromatic structure, forms π-π interactions and interfacial anchoring between the carbon fiber surface and the resin matrix, significantly improving the interfacial bonding strength between the carbon fiber and the epoxy resin. Through these multi-scale synergistic effects, the resulting epoxy resin-based carbon fiber prepreg significantly improves interlaminar toughness, impact resistance, and crack propagation resistance while maintaining high strength and modulus. Attached Figure Description

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Figure 1 The infrared spectra of unmodified epoxy resin and synergistically modified epoxy resin are compared. Figure 2 A comparison chart showing the interlaminar shear strength test results for samples with different mix proportions. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0021] Example 1: The purpose of this example is to verify that when the components are in a low dosage range, the present invention can still construct a host-guest structure-dynamic borate ester-cage node synergistic modified epoxy network and obtain a carbon fiber prepreg with good toughness.

[0022] S1, Preparation of Synergistically Modified Epoxy Resin 35 parts of bisphenol F type epoxy resin and 10 parts of tetrafunctional glycidylamine type epoxy resin were added to a reaction vessel, heated to 65°C under nitrogen protection, and stirred at 300 rpm. Then, 0.5 parts of hydroxypropyl-β-cyclodextrin and 0.2 parts of 1-adamantanemethylamine were added, and the reaction was continued for 1 hour to allow hydroxypropyl-β-cyclodextrin and 1-adamantanemethylamine to form a host-guest inclusion structure, thus obtaining a host-guest structure modified epoxy resin intermediate. Subsequently, 0.3 parts of 3-aminophenylboronic acid were added to the system. Add 0.3 parts of tannic acid to adjust the pH of the system to 7.5, and stir at 300 rpm for 1.5 h at 70 °C to form a dynamic borate ester structure, thus obtaining a dynamic borate ester network modified epoxy resin intermediate; then add 0.5 parts of octa(glycidyl ether propyl)silsesquioxane and 0.3 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane to the system, and stir at 400 rpm for 1 h at 75 °C to obtain 70 parts of synergistically modified epoxy resin; S2, Preparation of preimpregnated resin system 70 parts of synergistically modified epoxy resin, 0.3 parts of 2,6-dihydroxytriptene, 2 parts of thermoplastic toughening agent, 0.2 parts of rheology modifier, and 0.5 parts of nanofiller were added to a mixing vessel and stirred at 400 rpm for 0.5 h at 60 °C to obtain a modified epoxy resin matrix mixture. Subsequently, 20 parts of curing agent and 0.2 parts of accelerator were added to the system and stirred at 300 rpm for 0.5 h at 50 °C to obtain a prepreg resin system. S3, Prepreg Preparation Eighty parts of carbon fiber were impregnated in a prepreg resin system at 50°C for 3 minutes to allow the resin to fully impregnate the carbon fiber. After adjusting the resin content by scraping, the carbon fiber was pre-cured at 80°C for 5 minutes to obtain a high-toughness epoxy resin-based carbon fiber prepreg.

[0023] Example 2: The purpose of this example is to verify that when the components are in a moderate proportion, the toughness and interfacial bonding performance of epoxy resin-based carbon fiber prepreg can be significantly improved through the synergistic effect of host-guest structure, dynamic borate ester bond and cage-like silsesquioxane nodes.

[0024] S1, Preparation of Synergistically Modified Epoxy Resin 48 parts of bisphenol F type epoxy resin and 20 parts of tetrafunctional glycidylamine type epoxy resin were added to a reactor, heated to 75°C under nitrogen protection and stirred at 400 rpm. Then, 2 parts of hydroxypropyl-β-cyclodextrin and 1 part of 1-adamantanemethylamine were added, and the reaction was carried out for 1.5 h to obtain a host-guest structure modified epoxy resin intermediate. Then, 1.5 parts of 3-aminophenylboronic acid and 1.5 parts of tannic acid were added, the pH of the system was adjusted to 8.5, and the reaction was carried out at 80°C and stirred at 450 rpm for 2 h to obtain a dynamic borate ester network modified epoxy resin intermediate. Then, 2.5 parts of octa(glycidyl ether propyl)silsesquioxane and 1.5 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane were added, and the reaction was carried out at 85°C and stirred at 550 rpm for 2 h to obtain 85 parts of synergistically modified epoxy resin. Figure 1 The infrared spectral comparison shows that the unmodified epoxy resin exhibits a distinct epoxy group characteristic absorption peak at 915 cm⁻¹, along with aromatic ring skeletal vibration peaks near 1600 cm⁻¹ and 1510 cm⁻¹. The modified sample shows a significantly enhanced hydroxyl absorption peak near 3400 cm⁻¹, indicating the successful introduction of β-cyclodextrin and tannic acid into the system. A new B–O characteristic absorption peak appears near 1360 cm⁻¹, indicating the formation of a borate ester structure in the system. Simultaneously, a distinct Si–O–Si characteristic absorption peak appears near 1100 cm⁻¹, indicating the successful introduction of octa(glycidyl ether propyl)silsesquioxane into the epoxy resin network. The weakened intensity of the epoxy group characteristic peak at 915 cm⁻¹ indicates that some epoxy groups participated in the modification reaction. These results demonstrate the successful construction of a synergistically modified epoxy resin. S2, Preparation of preimpregnated resin system 85 parts of synergistically modified epoxy resin, 2 parts of 2,6-dihydroxytriptene, 7 parts of thermoplastic toughening agent, 1.5 parts of rheology modifier and 2.5 parts of nanofiller were added to a reactor and stirred and dispersed at 550 rpm for 1 h at 70 °C to obtain a modified epoxy resin matrix mixture; then 32 parts of curing agent and 1 part of accelerator were added and stirred at 450 rpm for 0.8 h at 60 °C to obtain a prepreg resin system; S3, Prepreg Preparation 115 parts of carbon fiber were impregnated in a prepreg resin system at 60°C for 6 minutes to allow the resin to fully impregnate the carbon fiber. After adjusting the resin content by scraping, the carbon fiber was pre-cured at 95°C for 12 minutes to obtain a high-toughness epoxy resin-based carbon fiber prepreg.

[0025] Example 3: The purpose of this example is to verify that when each component is in a high dosage range, the multi-scale synergistic crosslinking network constructed by the present invention can still maintain good structural stability and further improve the impact resistance and interlayer toughness of the material.

[0026] S1, Preparation of Synergistically Modified Epoxy Resin 60 parts of bisphenol F type epoxy resin and 30 parts of tetrafunctional glycidylamine type epoxy resin were added to a reactor, heated to 85℃ under nitrogen protection and stirred at 500 rpm, then 4 parts of hydroxypropyl-β-cyclodextrin and 2 parts of 1-adamantanemethylamine were added, and the reaction was carried out for 2 h to obtain a host-guest structure modified epoxy resin intermediate; then 3 parts of 3-aminophenylboronic acid and 3 parts of tannic acid were added, the pH of the system was adjusted to 9.0, and the reaction was carried out at 90℃ and stirred at 600 rpm for 3 h to obtain a dynamic borate ester network modified epoxy resin intermediate; then 5 parts of octa(glycidyl ether propyl)silsesquioxane and 3 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane were added, and the reaction was carried out at 95℃ and stirred at 700 rpm for 3 h to obtain 100 parts of synergistically modified epoxy resin. S2, Preparation of preimpregnated resin system 100 parts of synergistically modified epoxy resin, 4 parts of 2,6-dihydroxytriptene, 12 parts of thermoplastic toughening agent, 3 parts of rheology modifier and 5 parts of nanofiller were added to a mixing tank and dispersed by stirring at 700 rpm for 1.5 h at 80 °C to obtain a modified epoxy resin matrix mixture; then 45 parts of curing agent and 2 parts of accelerator were added and stirred at 600 rpm for 1 h at 70 °C to obtain a prepreg resin system; S3, Prepreg Preparation 150 parts of carbon fiber were impregnated in a prepreg resin system at 70°C for 10 minutes to allow the resin to fully impregnate the carbon fiber. After adjusting the resin content by scraping, the carbon fiber was pre-cured at 110°C for 20 minutes to obtain a high-toughness epoxy resin-based carbon fiber prepreg.

[0027] Comparative Example 1: The purpose of this comparative example is to verify the effect of using only the host-guest inclusion structure to modify epoxy resin on the toughness and interfacial bonding performance of epoxy resin-based carbon fiber prepreg.

[0028] S1, Preparation of epoxy resin modified with a single host-guest structure 48 parts of bisphenol F type epoxy resin and 20 parts of tetrafunctional glycidylamine type epoxy resin were added to a reaction vessel, heated to 75°C under nitrogen protection and stirred at 400 rpm, then 2 parts of hydroxypropyl-β-cyclodextrin and 1 part of 1-adamantane methylamine were added, and the reaction was carried out for 1.5 h to form a host-guest inclusion structure between hydroxypropyl-β-cyclodextrin and 1-adamantane methylamine, thus obtaining 85 parts of epoxy resin with a single host-guest structure. S2, Preparation of preimpregnated resin system 85 parts of a single host-guest structure modified epoxy resin, 2 parts of 2,6-dihydroxytriptene, 7 parts of thermoplastic toughening agent, 1.5 parts of rheology modifier, and 2.5 parts of nanofiller were added to a reactor and dispersed at 550 rpm for 1 h at 70 °C to obtain a modified epoxy resin matrix mixture; then 32 parts of curing agent and 1 part of accelerator were added and stirred at 450 rpm for 0.8 h at 60 °C to obtain a prepreg resin system; S3, Prepreg Preparation 115 parts of carbon fiber were impregnated in a prepreg resin system at 60°C for 6 minutes to allow the resin to fully impregnate the carbon fiber. After adjusting the resin content by scraping, the resin was pre-cured at 95°C for 12 minutes to obtain epoxy resin-based carbon fiber prepreg.

[0029] Comparative Example 2: The purpose of this comparative example is to verify the effect of using only dynamic borate ester structure to modify epoxy resin on the toughness and interfacial bonding performance of epoxy resin-based carbon fiber prepreg.

[0030] S1, Preparation of epoxy resin modified with a single dynamic borate ester structure 48 parts of bisphenol F type epoxy resin and 20 parts of tetrafunctional glycidylamine type epoxy resin were added to a reaction vessel, heated to 75°C under nitrogen protection and stirred at 400 rpm, then 1.5 parts of 3-aminophenylboronic acid and 1.5 parts of tannic acid were added, the pH of the system was adjusted to 8.5, and the reaction was carried out at 80°C and stirred at 450 rpm for 2 hours to form a dynamic borate ester structure, thus obtaining 85 parts of epoxy resin modified with a single dynamic borate ester structure. S2, Preparation of preimpregnated resin system 85 parts of a single dynamic borate ester modified epoxy resin, 2 parts of 2,6-dihydroxytriptene, 7 parts of thermoplastic toughening agent, 1.5 parts of rheology modifier and 2.5 parts of nanofiller were added to a reactor and stirred and dispersed at 550 rpm for 1 h at 70 °C to obtain a modified epoxy resin matrix mixture; then 32 parts of curing agent and 1 part of accelerator were added and stirred at 450 rpm for 0.8 h at 60 °C to obtain a prepreg resin system; S3, Prepreg Preparation 115 parts of carbon fiber were impregnated in a prepreg resin system at 60°C for 6 minutes to allow the resin to fully impregnate the carbon fiber. After adjusting the resin content by scraping, the resin was pre-cured at 95°C for 12 minutes to obtain epoxy resin-based carbon fiber prepreg.

[0031] Comparative Example 3: The purpose of this comparative example is to verify the effect of not adding the organic small molecule 2,6-dihydroxytriptene on the toughness and interfacial bonding performance of epoxy resin-based carbon fiber prepreg when using a host-guest structure, dynamic borate ester bonds and cage-like silsesquioxane nodes to synergistically modify epoxy resin.

[0032] S1, Preparation of Synergistically Modified Epoxy Resin 48 parts of bisphenol F type epoxy resin and 20 parts of tetrafunctional glycidylamine type epoxy resin were added to a reactor, heated to 75°C under nitrogen protection and stirred at 400 rpm. Then, 2 parts of hydroxypropyl-β-cyclodextrin and 1 part of 1-adamantanemethylamine were added, and the reaction was carried out for 1.5 h to obtain a host-guest structure modified epoxy resin intermediate. Then, 1.5 parts of 3-aminophenylboronic acid and 1.5 parts of tannic acid were added, the pH of the system was adjusted to 8.5, and the reaction was carried out at 80°C and stirred at 450 rpm for 2 h to obtain a dynamic borate ester network modified epoxy resin intermediate. Then, 2.5 parts of octa(glycidyl ether propyl)silsesquioxane and 1.5 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane were added, and the reaction was carried out at 85°C and stirred at 550 rpm for 2 h to obtain 85 parts of synergistically modified epoxy resin. S2, Preparation of preimpregnated resin system 85 parts of synergistic modified epoxy resin, 7 parts of thermoplastic toughening agent, 1.5 parts of rheology modifier and 2.5 parts of nanofiller were added to a reactor and stirred and dispersed at 550 rpm for 1 h at 70 °C to obtain a modified epoxy resin matrix mixture; then 32 parts of curing agent and 1 part of accelerator were added and stirred at 450 rpm for 0.8 h at 60 °C to obtain a prepreg resin system. S3, Prepreg Preparation 115 parts of carbon fiber were impregnated in a prepreg resin system at 60°C for 6 minutes to allow the resin to fully impregnate the carbon fiber. After adjusting the resin content by scraping, the resin was pre-cured at 95°C for 12 minutes to obtain epoxy resin-based carbon fiber prepreg.

[0033] Performance testing: 1. Interlaminar shear strength test method The carbon fiber prepregs obtained in the examples and comparative examples were cured and molded under hot pressing to prepare carbon fiber composite laminate specimens. The specimens were cut into short beam specimens with dimensions of 20 mm × 10 mm × 2 mm, and short beam shear tests were performed using a universal testing machine. The loading speed was set to 1 mm / min, and the span-to-thickness ratio was 4:1. The maximum failure load of the specimens during loading was recorded, and the interlaminar shear strength was calculated according to the standard formula to evaluate the interlaminar bonding performance of the composite materials in different examples and comparative examples.

[0034] 2. Impact strength test method The carbon fiber composite laminates prepared in the examples and comparative examples were processed into specimens with dimensions of 80 mm × 10 mm × 4 mm, and their impact performance was tested using a pendulum impact testing machine. Before testing, the specimens were notched with a notch depth of 2 mm. The specimens were then fixed on the impact testing device, and impact loading was performed under specified energy conditions. The impact resistance and toughness of the material were evaluated by recording the energy absorbed by the specimens during the impact and calculating the impact strength.

[0035] 3. Fracture toughness testing methods The carbon fiber composite laminates prepared in the examples and comparative examples were processed into single-sided notched bending specimens with dimensions of 120 mm × 15 mm × 4 mm, and an initial crack was pre-induced in the middle of the specimen. Fracture toughness tests were performed on a universal testing machine using a three-point bending method, with a loading speed set to 1 mm / min. By recording the load-displacement curves of the specimens during crack propagation and obtaining the fracture toughness parameters of the materials according to standard calculation methods, the resistance of different material systems to crack propagation was evaluated.

[0036] 4. Interfacial Shear Strength Test Method Carbon fiber composite material samples from the examples and comparative examples were selected, and the interfacial bonding performance between carbon fibers and the resin matrix was tested using the microdroplet method. First, resin microdroplets were formed on the surface of a single carbon fiber and cured. Then, the sample was fixed on a micromechanical testing device, and axial loads were gradually applied to cause the resin microdroplets to debond and slide. The debonding loads were recorded, and the interfacial shear strength was calculated by combining the fiber diameter and resin coating length to evaluate the interfacial bonding effect between carbon fibers and resin.

[0037] Table 1 Performance test results of different embodiments and comparative examples

[0038] As shown in Table 1, the carbon fiber prepregs prepared in the embodiments and comparative examples of the present invention exhibit significant differences in interlaminar shear strength, impact strength, fracture toughness, and interfacial shear strength. The overall performance of the embodiments is higher than that of the comparative examples, indicating that the present invention, through the construction of a modified epoxy resin system with a host-guest inclusion structure, dynamic borate ester bonds, and the synergistic effect of cage-like silsesquioxane nodes, and the introduction of 2,6-dihydroxytriptene for interfacial regulation, can significantly improve the comprehensive mechanical properties of carbon fiber composites.

[0039] Based on the interlaminar shear strength test results Figure 2The interlaminar shear strengths of Examples 1-3 were 76.5 MPa, 92.7 MPa, and 85.4 MPa, respectively, all significantly higher than those of Comparative Examples 1-3 (63.8 MPa, 66.2 MPa, and 71.6 MPa), with Example 2 exhibiting the highest interlaminar shear strength. This indicates that the host-guest inclusion structure and dynamic borate ester network can effectively improve the structural toughness of the epoxy resin matrix and enhance the interfacial bonding between carbon fibers and resin, thereby improving the stability of the interlaminar structure of the composite material.

[0040] The impact strength test results show that the impact strengths of Examples 1-3 reached 58.3 kJ / m², 73.6 kJ / m², and 67.2 kJ / m², respectively, which are significantly higher than those of the comparative examples. In particular, Example 2 exhibited the highest impact strength, indicating that under appropriate formulation conditions, the multi-synergistic modified structure can effectively dissipate energy under external impact, thereby significantly improving the impact resistance and overall toughness of the material.

[0041] The fracture toughness test results show that the fracture toughness parameter KIC of the embodiments is significantly higher than that of the comparative examples. Specifically, Example 2 reaches 2.08 MPa·m^1 / 2, while the comparative examples are all below 1.50 MPa·m^1 / 2. This indicates that by constructing a dynamic cross-linked network formed by a movable host-guest structure and dynamic borate ester bonds, more energy dissipation pathways can be provided during crack propagation, thereby effectively inhibiting crack propagation and improving the crack resistance of the material.

[0042] The interfacial shear strength test results show that the interfacial shear strength of the examples is significantly higher than that of the comparative examples, with Example 2 reaching 79.4 MPa. This is mainly because 2,6-dihydroxytriptene has a rigid aromatic structure, which can form π-π interactions between the carbon fiber surface and the epoxy resin matrix, improving the interfacial bonding strength and thus significantly improving the interfacial compatibility between the carbon fiber and the resin matrix.

[0043] In summary, this invention significantly improves the interlaminar shear strength, impact strength, fracture toughness, and interfacial bonding performance of epoxy resin-based carbon fiber prepregs by constructing a three-dimensional dynamic crosslinking network with synergistic effects of host-guest inclusion structures, dynamic borate ester bonds, and cage-like silsesquioxane nodes, and by introducing 2,6-dihydroxytriptene for interface regulation. Among these, Example 2 exhibits the best overall performance, fully demonstrating the effectiveness and superiority of the technical solution of this invention.

Claims

1. A high-toughness epoxy resin-based carbon fiber prepreg, characterized in that, The prepreg comprises the following raw materials in parts by weight: 80-150 parts carbon fiber, 70-100 parts synergistically modified epoxy resin, 0.3-4 parts 2,6-dihydroxytriptene, 20-45 parts curing agent, 0.2-2 parts accelerator, 2-12 parts thermoplastic toughening agent, 0.2-3 parts rheology modifier, and 0.5-5 parts nanofiller. The synergistically modified epoxy resin is obtained by forming a host-guest inclusion structure with hydroxypropyl-β-cyclodextrin and 1-adamantanemethylamine, and forming dynamic borate ester bonds with tannic acid through 3-aminophenylboronic acid, while introducing octa(glycidyl ether propyl)silsesquioxane to construct cage-like rigid nodes, thereby synergistically modifying bisphenol F type epoxy resin and tetrafunctional glycidylamine type epoxy resin to construct a three-dimensional dynamic crosslinking network.

2. The high-toughness epoxy resin-based carbon fiber prepreg according to claim 1, characterized in that, The synergistically modified epoxy resin comprises the following raw materials in parts by weight: 35-60 parts of bisphenol F type epoxy resin, 10-30 parts of tetrafunctional glycidylamine type epoxy resin, 0.5-4 parts of hydroxypropyl-β-cyclodextrin, 0.2-2 parts of 1-adamantanemethylamine, 0.3-3 parts of 3-aminophenylboronic acid, 0.3-3 parts of tannic acid, 0.5-5 parts of octa(glycidyl ether propyl)silsesquioxane, and 0.3-3 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

3. A high-toughness epoxy resin-based carbon fiber prepreg according to claim 1 or 2, characterized in that, The preparation method of the synergistically modified epoxy resin includes the following steps: (1) Bisphenol F type epoxy resin, tetrafunctional glycidylamine type epoxy resin, hydroxypropyl-β-cyclodextrin and 1-adamantane methylamine are mixed and stirred to form a host-guest inclusion structure between hydroxypropyl-β-cyclodextrin and 1-adamantane methylamine, thereby obtaining a host-guest structure modified epoxy resin intermediate. (2) Add 3-aminophenylboronic acid and tannic acid to the host-guest structure modified epoxy resin intermediate and react them to form a dynamic borate ester structure, thereby obtaining a dynamic borate ester network modified epoxy resin intermediate. (3) Add octa(glycidyl ether propyl) silsesquioxane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane to the dynamic borate ester network modified epoxy resin intermediate and react to obtain a synergistically modified epoxy resin.

4. The high-toughness epoxy resin-based carbon fiber prepreg according to claim 3, characterized in that, The reaction conditions for step (1) are as follows: under nitrogen protection, the reaction is carried out at 65-85°C, the stirring speed is 300-500 rpm, and the reaction time is 1-2 h.

5. The high-toughness epoxy resin-based carbon fiber prepreg according to claim 3, characterized in that, The reaction conditions for step (2) are as follows: the reaction is carried out at 70-90°C, the pH of the system is 7.5-9.0, the stirring speed is 300-600 rpm, and the reaction time is 1.5-3h.

6. The high-toughness epoxy resin-based carbon fiber prepreg according to claim 3, characterized in that, The reaction conditions for step (3) are as follows: the reaction is carried out at 75-95°C, the stirring speed is 400-700 rpm, and the reaction time is 1-3 h.

7. The high-toughness epoxy resin-based carbon fiber prepreg according to claim 1, characterized in that, The curing agent is a mixture of 4,4'-diaminodiphenyl sulfone and diaminodiphenylmethane in a mass ratio of (3-8):(2-5); the accelerator is a mixture of 2-methylimidazole and 2-ethyl-4-methylimidazole in a mass ratio of (1-4):(1-3); the thermoplastic toughening agent is a mixture of polyethersulfone and polyamide imide in a mass ratio of (4-10):(1-4); the rheology modifier is a mixture of fumed silica and polyamide wax in a mass ratio of (2-6):(1-3); and the nanofiller is a mixture of nano silica and nano alumina in a mass ratio of (3-8):(1-4).

8. A method for preparing a high-toughness epoxy resin-based carbon fiber prepreg, characterized in that, The preparation method includes the following steps: S1, the synergistic modified epoxy resin, 2,6-dihydroxytriptene, thermoplastic toughening agent, rheology modifier and nanofiller are mixed and stirred to disperse to obtain a modified epoxy resin matrix mixture; S2, add curing agent and accelerator to the modified epoxy resin matrix mixture and mix to obtain a prepreg resin system; S3 involves impregnating carbon fibers with a prepreg resin system to ensure uniform resin impregnation. After adjusting the resin content by scraping, a pre-curing treatment is performed to obtain a high-toughness epoxy resin-based carbon fiber prepreg.

9. The method for preparing a high-toughness epoxy resin-based carbon fiber prepreg according to claim 8, characterized in that, The reaction conditions for step S1 are: stirring and dispersing at 60–80°C, stirring speed of 400–700 rpm, and dispersion time of 0.5–1.5 h; the reaction conditions for step S2 are: mixing and stirring at 50–70°C, stirring speed of 300–600 rpm, and mixing time of 0.5–1 h.

10. The method for preparing a high-toughness epoxy resin-based carbon fiber prepreg according to claim 8, characterized in that, The reaction conditions for step S3 are as follows: the impregnation temperature of the carbon fiber in the resin system is 50-70℃, the impregnation time is 3-10 min, the pre-curing temperature is 80-110℃, and the pre-curing time is 5-20 min.

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