High-strength bismaleimide resin material and preparation method thereof

Abstract

The application belongs to the technical field of polymer composite materials, and particularly relates to a high-strength bismaleimide resin material and a preparation method thereof. The bismaleimide resin material comprises the following components in parts by weight: bismaleimide resin 50-60 parts, allyl compound 40-50 parts, modified graphene 1-3 parts, and dispersed filler 0.1-0.5 parts. The dispersed filler is composed of modified inorganic nanoparticles and modified four-needle-shaped zinc oxide whiskers in a mass ratio of (0.1-1):1. The four-needle-shaped zinc oxide whiskers can promote the dispersion of graphene with a large lamellar structure from a macroscopic perspective, so that the graphene is uniformly dispersed in the bismaleimide resin matrix. The inorganic nanoparticles can play a lubricating and isolating role to prevent the agglomeration between graphene lamellar layers in a small range. The addition of the graphene composite reinforcing filler can improve the rigidity of the bismaleimide resin material and also improve the toughness of the composite material.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to a high-strength bismaleimide resin material and its preparation method. Background Technology

[0002] Polymer-based composite materials are lightweight, high-strength, heat-resistant, corrosion-resistant, and highly designable, making them widely used in aerospace, mechanical, and electronic fields. Currently, the main matrix resins for advanced composite materials include polyimide, epoxy resin, and bismaleimide resin. Among these, bismaleimide combines the excellent processing properties of epoxy resin with the superior high-temperature resistance, radiation resistance, and corrosion resistance of polyimide resin, thus meeting the requirements for matrix resins in advanced composite materials. Therefore, bismaleimide has become the preferred material for developing matrix resins.

[0003] Bismaleimide resins are compounds in which the carbon-carbon double bonds on the maleimide ring are active groups. The properties of bismaleimide mainly depend on the double bonds and bridging groups on the maleimide. Because the bismaleimide molecule contains highly heat-resistant benzene rings and imide heterocycles, it exhibits excellent heat resistance. The glass transition temperature of bismaleimide is typically above 250℃, and its operating temperature range is 180-230℃. Within a certain range, the thermal decomposition temperature of bismaleimide increases with increasing crosslinking density, and the thermal decomposition temperature of aromatic bismaleimides is higher than that of aliphatic bismaleimides. Bismaleimide has poor solubility, being insoluble in common solvents such as dichloromethane, ethanol, and acetone, but soluble only in highly polar solvents such as N-methylpyrrolidone and dimethylformamide. This is mainly due to the polarity and symmetry of the bismaleimide molecule. The carbon-carbon double bonds in bismaleimide molecules are highly reactive, making them prone to copolymerization with compounds containing active hydrogen and unsaturated double bonds. Cured bismaleimide products have a dense structure and high specific strength and specific modulus; however, due to their high crosslinking density, high curing stress, and poor molecular chain flexibility, the cured products are quite brittle. Therefore, improving the toughness of bismaleimide resins is crucial for expanding their application areas.

[0004] Toughening modification of bismaleimide resins mainly focuses on two aspects: first, reducing the crosslinking density of the bismaleimide resin, primarily achieved by decreasing the number of reactive groups per unit volume during the curing reaction; second, reducing the rigidity of the polymer chains by introducing flexible chain segments into the bismaleimide resin, such as the use of propylene compounds in industrial production for toughening modification. Benefiting from the ease with which bismaleimide monomers can copolymerize with various compounds such as propylene compounds, amino compounds, and cyanates, multiple pathways exist to meet the toughening modification requirements of bismaleimides, including propylene compound modification, thermoplastic resin modification, rubber toughening modification, diamine chain extension modification, and nanomaterial modification. Based on the different toughening methods, various toughening approaches can be categorized into internal toughening, external toughening, and combined toughening. CN108641356A discloses a graphene / graphene-like WS2 / bismaleimide composite material modified with a cyclotriphosphazene polymer and its preparation method. First, WS2 is exfoliated into graphene-like WS2 using low-energy ball milling and ultrasonication. Then, it is added together with graphene oxide to a high-temperature, high-pressure reactor, along with an appropriate amount of hydrazine hydrate, and reacted in a one-pot hydrothermal method to prepare graphene / graphene-like WS2. Next, using hexachlorocyclotriphosphazene and branched polyethyleneimine as raw materials, and triethylamine as an acid-binding agent, the cyclotriphosphazene polymer-modified graphene / graphene-like WS2 is prepared using an in-situ template method. Finally, it is mixed with diphenylmethane-type bismaleimide and diallyl bisphenol A in a certain proportion to prepare the composite material. The prepared composite material exhibits good interfacial bonding strength, excellent mechanical properties, and tribological properties. However, the composite material prepared by this technology has a complex process, limited improvement in mechanical strength, and is difficult to widely apply. Summary of the Invention

[0005] In order to overcome the problems existing in the prior art, the purpose of this invention is to provide a simple, easy-to-implement, process-controllable, and mass-producible high-strength bismaleimide resin composite material and its preparation method.

[0006] The present invention solves the above-mentioned technical problems by means of the following technical solution:

[0007] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0008] The mixture comprises 50-60 parts of bismaleimide resin, 40-50 parts of allyl compound, 1-3 parts of modified graphene, and 0.1-0.5 parts of dispersion filler; wherein the dispersion filler is composed of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of (0.1-1):1.

[0009] Although bismaleimide resin itself possesses high temperature resistance, excellent mechanical properties, and moisture resistance, it exhibits several challenges in actual production, including high melting point, poor solubility in common reagents, high curing temperature, and significant brittleness, making it difficult to process and mold. Among these, brittleness is the most difficult problem to solve during the processing of bismaleimide resin. Therefore, this invention adds a certain amount of allyl compound to modify it and improve its processing performance. While the reinforcing effect of allyl compound as an organic material is limited, the copolymerization of allyl compound and bismaleimide results in a stable, easily soluble, and well-adhesive prepolymer, which is beneficial for the addition of graphene inorganic reinforcing fillers. Furthermore, the mass ratio of bismaleimide resin to allyl compound is 1:(0.65-0.85); even further, it is 1:(0.78-0.82; an appropriate amount of allyl compound can achieve both reinforcing and toughening effects.

[0010] As a nanosheet reinforcing filler, graphene has a two-dimensional sheet structure with a small thickness and a lateral dimension typically in the micrometer range. This invention uses graphene as an inorganic reinforcing filler for bismaleimide. When the system is subjected to external stress, stress concentration easily occurs at the interface between graphene and the resin matrix, leading to internal cracks. However, due to its sheet-like structure, graphene generally has a large specific surface area and a large contact area with the resin matrix, which can prevent further crack propagation, thereby absorbing more energy and achieving a toughening effect. Furthermore, when the material is subjected to impact loads, an appropriate amount of graphene within the system undergoes plastic deformation, absorbing some of the impact energy, thus achieving a toughening effect. However, it should be noted that when the volume fraction of graphene in the system is too high, microcracks within the system are prone to develop into macrocracks, leading to a decrease in material performance.

[0011] However, precisely because graphene is a sheet-like structure with a large specific surface area, it has high surface activity and strong van der Waals forces, making it prone to aggregation and even reforming into a graphite structure. Therefore, obtaining and maintaining the state of graphene dispersions remains a challenge. To prevent graphene aggregation, etching is commonly used to modify it. However, surface etching of graphene often damages the graphene lattice, leading to a decrease in its performance. Therefore, to address the problem of graphene aggregation, this invention adds a certain amount of modified tetraneedle-shaped zinc oxide whiskers and modified inorganic nanoparticles. Tetraneedle-shaped zinc oxide whiskers are micro-single-crystal fibers that can grow into a tetraneedle structure, with four needles extending from the same center into three-dimensional space. To date, tetraneedle-shaped zinc oxide whiskers are the only whiskers in the whisker family with a three-dimensional spatial structure. Compared to ordinary fibrous zinc oxide whiskers, tetraneedle-shaped zinc oxide whiskers exhibit isotropic spatial distribution. Therefore, the processing of tetraneedle-shaped zinc oxide whiskers avoids the possibility of orientation along the stress direction, ensuring the prepared composite material is isotropic. Simultaneously, the addition of a small amount of particulate inorganic nanoparticles facilitates their distribution between graphene sheets, preventing agglomeration of graphene sheets during blending. Furthermore, the tetraneedle-shaped zinc oxide whiskers and inorganic nanoparticles, as rigid structures, can promote the dispersion and deformation of flexible graphene, thereby improving the mechanical properties of the bismaleimide composite material.

[0012] Therefore, a composite material is created by combining rigid tetrapod-shaped zinc oxide whiskers, inorganic nanoparticles, and flexible graphene. The tetrapod-shaped zinc oxide whiskers macroscopically promote the dispersion of graphene with its large sheet structure, ensuring its uniform dispersion within the bismaleimide resin matrix. The inorganic nanoparticles act as lubricants and separators, preventing agglomeration between graphene sheets within small areas. However, as a dispersing agent for graphene, the amount of inorganic nanoparticles should not be excessive; otherwise, dispersion difficulties will arise. Furthermore, during the tensile fracture process of the composite material, the tetrapod-shaped whiskers exhibit superior stress transmission and dissipation capabilities compared to ordinary one-dimensional whiskers, improving both the rigidity and toughness of the composite material. Specifically, the dispersant content is 0.15-0.35 parts; an appropriate amount of dispersant can effectively perform its dispersing and reinforcing functions while preventing dispersion difficulties that might result from excessive inorganic filler.

[0013] Furthermore, the bismaleimide resin is one or more of 4,4-bismaleimide diphenylmethane, 4,4-bismaleimide diphenyl ether, and 4,4-bismaleimide diphenyl sulfone.

[0014] Furthermore, the allyl compound is one or more of diallyl bisphenol A (i.e., 2,2-diallyl bisphenol A), diallyl bisphenol S, and allyl linear phenolic resin.

[0015] Furthermore, the modified graphene is graphene containing active polar groups. Furthermore, the modified graphene is present in 1-2 parts. An appropriate amount of graphene can provide both reinforcement and toughening effects. First, graphene itself possesses excellent mechanical properties, and its addition can improve the overall mechanical properties of the composite material. Second, the aromatic structure in bismaleimide can form a strong π-π conjugation with graphene, resulting in good bonding between graphene and the resin matrix; a good interface is beneficial for improving mechanical properties. On the other hand, since the surface of graphene usually has a certain degree of defects and some residual oxygen-containing functional groups, this increases the hydrogen bond density in the composite material system, and the crosslinking density also increases accordingly, which is also beneficial for improving the strength of the composite material. When the amount of graphene added is too large, it exceeds the dispersing capacity of the dispersing filler, leading to a certain degree of agglomeration of graphene layers, causing stress concentration in the material, thereby reducing the mechanical properties of the composite material.

[0016] Furthermore, the modified inorganic nanoparticles are inorganic nanoparticles containing active polar groups; the modified tetraneedle-shaped zinc oxide whiskers are tetraneedle-shaped zinc oxide whiskers containing active polar groups. The type of active polar groups is not particularly limited; the main purpose of modification is to improve the compatibility between the inorganic filler and the matrix resin, improve the interfacial properties between the filler and the resin, and enable the inorganic filler to effectively transfer loads, thereby better achieving the goal of improving mechanical properties.

[0017] Furthermore, the active polar group is one or more of amino, epoxy, hydroxy, carboxyl, cyanate, and maleimide groups.

[0018] Furthermore, there are no particular limitations on the modification method; coupling agents commonly used in the art can be used for modification. For example, coupling agents containing amino, epoxy, hydroxyl, carboxyl, cyanate, or maleimide groups can be used for modification.

[0019] Specifically, graphene, tetraneedle-shaped zinc oxide whiskers, or inorganic nanoparticles are uniformly dispersed in a mixed solution of ethanol and water, and then a coupling agent is added. The mixture is reacted at 50-70°C for 1-2 hours. After filtration, washing, and drying, modified graphene, modified tetraneedle-shaped zinc oxide whiskers, or modified inorganic nanoparticles are obtained. The mass ratio of the coupling agent to graphene, tetraneedle-shaped zinc oxide whiskers, or inorganic nanoparticles is (0.1-1):1.

[0020] Furthermore, the coupling agent is one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylethyldiethoxysilane, γ-aminopropylethyldiethoxysilane, γ-glycidyletheroxypropyltriethoxysilane, γ-glycidyletheroxypropylmethyldiethoxysilane, γ-glycidyletheroxypropylmethyldiethoxysilane, γ-glycidyletheroxypropylethyldiethoxysilane, γ-glycidyletheroxypropylethyldiethoxysilane, γ-glycidyletheroxypropylethyldiethoxysilane, γ-isocyanate-propyltrimethoxysilane, γ-methacryloyloxypropylcarboxytriethoxysilane, γ-acryloyloxypropylcarboxytrimethoxysilane, and γ-[bis(2-hydroxyethyl)amino]propanetriethoxysilane.

[0021] Furthermore, the inorganic nanoparticles are one or more of nano-silica, nano-titanium dioxide, nano-zinc oxide, nano-boron nitride, nano-calcium carbonate, and nano-wollastonite.

[0022] The inorganic nanoparticles have an average particle size of 10-100 nm.

[0023] On the other hand, the present invention also provides a method for preparing a high-strength bismaleimide resin material, comprising the following steps:

[0024] (1) Mix the bismaleimide resin and allyl compound evenly, and heat to prepolymerize until the solution is transparent to obtain the prepolymer;

[0025] (2) Add modified graphene and dispersing filler to the prepolymer, mix evenly to obtain a mixture;

[0026] (3) Pour the mixture into a mold, degas under vacuum, and heat to cure, and you will get a high-strength bismaleimide resin material.

[0027] Furthermore, the heating temperature is 120-140℃. The method of adding modified graphene and dispersing filler is not particularly limited. Modified graphene can be added to the prepolymer first, mixed thoroughly, and then the dispersing filler can be added; or the dispersing filler can be added to the prepolymer first, mixed thoroughly, and then the modified graphene can be added. In particular, the dispersing filler can be added first, mixed thoroughly, and then the modified graphene can be added, so that the dispersing filler is dispersed in advance, which can better promote the mixing of graphene.

[0028] Furthermore, the degassing time is 10-30 minutes.

[0029] Furthermore, the heating and curing process is 145-155℃ / 1-1.5h + 155-165℃ / 1-1.5h + 175-185℃ / 1-1.5h + 195-205℃ / 1-1.5h.

[0030] Beneficial Effects: Because graphene has a large specific surface area and a sheet-like structure with high surface activity and strong van der Waals forces, graphene sheets are prone to aggregation. This invention adds a certain amount of modified tetra-needle zinc oxide whiskers and modified inorganic nanoparticles. The tetra-needle zinc oxide whiskers are spatially isotropic, avoiding the possibility of orientation along the stress direction during processing, thus ensuring the isotropic nature of the prepared composite material. Simultaneously, the addition of a small amount of particulate inorganic nanoparticles facilitates their distribution between graphene sheets, preventing agglomeration during blending. Specifically, the tetra-needle zinc oxide whiskers macroscopically promote the dispersion of graphene with its large sheet structure, ensuring uniform dispersion within the bismaleimide resin matrix, while the inorganic nanoparticles act as lubricants and separators, preventing agglomeration between graphene sheets in small areas. The addition of graphene composite reinforcing fillers improves both the rigidity and toughness of the bismaleimide resin material. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Unless otherwise specified, the raw materials used in the above examples and comparative examples are the same. Specifically, the bismaleimide resin is 4,4-bismaleimide diphenylmethane; the allyl compound is diallylbisphenol A; the graphene has a lateral size of 1-10 μm; the tetraneedle-shaped zinc oxide whiskers have a root diameter of 0.5-5 μm and a needle length of 10-50 μm; and the inorganic nanoparticles are nano-silica with an average particle size of 50 nm.

[0033] The specific preparation processes for the modified graphene, modified inorganic nanoparticles, and modified tetraneedle-shaped zinc oxide whiskers are all the same, specifically: graphene (or inorganic nanoparticles, or tetraneedle-shaped zinc oxide whiskers) is uniformly dispersed in a mixed solution of ethanol and water, and then γ-aminopropyltriethoxysilane is added, and the reaction is carried out at 60°C for 1.5 h; after filtration, washing, and drying, the modified graphene (or modified inorganic nanoparticles, or modified tetraneedle-shaped zinc oxide whiskers) is obtained; the mass ratio of γ-aminopropyltriethoxysilane to graphene (or inorganic nanoparticles, or tetraneedle-shaped zinc oxide whiskers) is 0.6:1.

[0034] The impact strength of high-strength bismaleimide resin materials shall be tested in accordance with GB / T 2571; the flexural strength shall be tested in accordance with GB / T 2570.

[0035] Example 1

[0036] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0037] The mixture comprises 50 parts of bismaleimide resin, 40 parts of allyl compound, 1 part of modified graphene, and 0.15 parts of dispersion filler; the dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 0.1:1.

[0038] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0039] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 120°C until the solution is transparent to obtain the prepolymer;

[0040] (2) Add the dispersing filler to the prepolymer and stir for 10 min; then add the modified graphene and stir for 20 min to obtain the mixture;

[0041] (3) Pour the mixture into a mold, degas under vacuum for 10 minutes, and then cure by heating at 145℃ / 1.5h + 155℃ / 1.5h + 185℃ / 1.5h + 195℃ / 1h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 15.55 kJ / m. 2 Its bending strength is 141 MPa.

[0042] Example 2

[0043] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0044] The mixture comprises 60 parts of bismaleimide resin, 49 parts of allyl compound, 2 parts of modified graphene, and 0.38 parts of dispersion filler; the dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 1:1.

[0045] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0046] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 135°C until the solution is transparent to obtain the prepolymer;

[0047] (2) Add the dispersing filler to the prepolymer and stir for 20 min; then add the modified graphene and stir for 10 min to obtain the mixture;

[0048] (3) Pour the mixture into a mold, degas under vacuum for 25 minutes, and then cure by heating at 155℃ / 1h + 165℃ / 1h + 185℃ / 1h + 205℃ / 1h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 18.18 kJ / m². 2 Its bending strength is 156 MPa.

[0049] Example 3

[0050] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0051] The mixture comprises 55 parts of bismaleimide resin, 44 parts of allyl compound, 1.7 parts of modified graphene, and 0.3 parts of dispersion filler; the dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 0.5:1.

[0052] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0053] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 130°C until the solution is transparent to obtain the prepolymer;

[0054] (2) Add modified graphene to the prepolymer and stir for 15 min; then add the dispersing filler and stir for 15 min to obtain a mixture;

[0055] (3) Pour the mixture into a mold, degas under vacuum for 20 minutes, and then cure by heating at 150℃ / 1h + 160℃ / 1.5h + 180℃ / 1.5h + 200℃ / 1h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 16.46 kJ / m². 2 Its bending strength is 147 MPa.

[0056] Example 4

[0057] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0058] The mixture comprises 60 parts of bismaleimide resin, 42 parts of allyl compound, 1 part of modified graphene, and 0.36 parts of dispersion filler; the dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 0.15:1.

[0059] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0060] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 122°C until the solution is transparent to obtain the prepolymer;

[0061] (2) Add the dispersing filler to the prepolymer and stir for 15 min; then add the modified graphene and stir for 15 min to obtain the mixture;

[0062] (3) Pour the mixture into a mold, degas under vacuum for 15 minutes, and then cure by heating at 145℃ / 1h + 155℃ / 1h + 185℃ / 1.5h + 205℃ / 1.5h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 15.83 kJ / m². 2 Its bending strength is 143 MPa.

[0063] Example 5

[0064] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0065] The mixture comprises 55 parts of bismaleimide resin, 44 parts of allyl compound, 3 parts of modified graphene, and 0.3 parts of dispersion filler; the dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 0.5:1.

[0066] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0067] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 130°C until the solution is transparent to obtain the prepolymer;

[0068] (2) Add the dispersing filler to the prepolymer and stir for 15 min; then add the modified graphene and stir for 15 min to obtain the mixture;

[0069] (3) Pour the mixture into a mold, degas under vacuum for 20 minutes, and then cure by heating at 150℃ / 1h + 160℃ / 1.5h + 180℃ / 1.5h + 200℃ / 1h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 16.58 kJ / m². 2 The bending strength is 150 MPa.

[0070] Example 6

[0071] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0072] The mixture contains 53 parts of bismaleimide resin, 41 parts of allyl compound, 1.2 parts of modified graphene, and 0.22 parts of dispersion filler. The dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 0.3:1.

[0073] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0074] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 126°C until the solution is transparent to obtain the prepolymer;

[0075] (2) Add the dispersing filler to the prepolymer and stir for 14 min; then add the modified graphene and stir for 16 min to obtain the mixture;

[0076] (3) Pour the mixture into a mold, degas under vacuum for 18 minutes, and then cure by heating at 150℃ / 1h + 160℃ / 1.5h + 175℃ / 1.5h + 205℃ / 1h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 16.41 kJ / m². 2 Its bending strength is 145 MPa.

[0077] Example 7

[0078] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0079] The mixture comprises 55 parts of bismaleimide resin, 44 parts of allyl compound, 1.7 parts of modified graphene, and 0.5 parts of dispersion filler; the dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 0.5:1.

[0080] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0081] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 130°C until the solution is transparent to obtain the prepolymer;

[0082] (2) Add the dispersing filler to the prepolymer and stir for 15 min; then add the modified graphene and stir for 15 min to obtain the mixture;

[0083] (3) Pour the mixture into a mold, degas under vacuum for 20 minutes, and then cure by heating at 150℃ / 1h + 160℃ / 1.5h + 180℃ / 1.5h + 200℃ / 1h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 17.15 kJ / m². 2 The bending strength is 151 MPa.

[0084] Example 8

[0085] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0086] The mixture contains 58 parts of bismaleimide resin, 47 parts of allyl compound, 1.8 parts of modified graphene, and 0.32 parts of dispersion filler. The dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 0.8:1.

[0087] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0088] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 133°C until the solution is transparent to obtain the prepolymer;

[0089] (2) Add the dispersing filler to the prepolymer and stir for 18 min; then add the modified graphene and stir for 14 min to obtain the mixture;

[0090] (3) Pour the mixture into a mold, degas under vacuum for 18 minutes, and then cure by heating at 150℃ / 1.5h + 155℃ / 1.2h + 180℃ / 1.2h + 195℃ / 1.2h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 18.08 kJ / m. 2 The bending strength is 155 MPa.

[0091] Example 9

[0092] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0093] The composition includes 56 parts of bismaleimide resin, 42.5 parts of allyl compound, 1.4 parts of modified graphene, and 0.28 parts of dispersion filler. The dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 0.6:1.

[0094] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0095] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 127°C until the solution is transparent to obtain the prepolymer;

[0096] (2) Add the dispersing filler to the prepolymer and stir for 20 min; then add the modified graphene and stir for 20 min to obtain the mixture;

[0097] (3) Pour the mixture into a mold, degas under vacuum for 20 minutes, and then cure by heating at 145℃ / 1.2h + 165℃ / 1.2h + 175℃ / 1.5h + 205℃ / 1.2h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 17.56 kJ / m². 2 Its bending strength is 152 MPa.

[0098] Example 10

[0099] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0100] The mixture comprises 55 parts of bismaleimide resin, 44 parts of allyl compound, 1.7 parts of modified graphene, and 0.3 parts of dispersion filler; the dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 0.5:1.

[0101] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0102] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 130°C until the solution is transparent to obtain the prepolymer;

[0103] (2) Add the dispersing filler to the prepolymer and stir for 15 min; then add the modified graphene and stir for 15 min to obtain the mixture;

[0104] (3) Pour the mixture into a mold, degas under vacuum for 20 minutes, and then cure by heating at 150℃ / 1h + 160℃ / 1.5h + 180℃ / 1.5h + 200℃ / 1h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 18.02 kJ / m². 2 Its bending strength is 157 MPa.

[0105] Comparative Example 1

[0106] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0107] The mixture comprises 55 parts of bismaleimide resin, 44 parts of allyl compound, 1.7 parts of modified graphene, and 0.3 parts of dispersing filler; the dispersing filler is modified inorganic nanoparticles.

[0108] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0109] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 130°C until the solution is transparent to obtain the prepolymer;

[0110] (2) Add the dispersing filler to the prepolymer and stir for 15 min; then add the modified graphene and stir for 15 min to obtain the mixture;

[0111] (3) Pour the mixture into a mold, degas under vacuum for 20 minutes, and then cure by heating at 150℃ / 1h + 160℃ / 1.5h + 180℃ / 1.5h + 200℃ / 1h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 12.74 kJ / m². 2 The bending strength is 125 MPa.

[0112] Comparative Example 2

[0113] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0114] The mixture comprises 55 parts of bismaleimide resin, 44 parts of allyl compound, 1.7 parts of modified graphene, and 0.3 parts of dispersion filler; the dispersion filler is modified tetraneedle-shaped zinc oxide whiskers.

[0115] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0116] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 130°C until the solution is transparent to obtain the prepolymer;

[0117] (2) Add the dispersing filler to the prepolymer and stir for 15 min; then add the modified graphene and stir for 15 min to obtain the mixture;

[0118] (3) Pour the mixture into a mold, degas under vacuum for 20 minutes, and then cure by heating at 150℃ / 1h + 160℃ / 1.5h + 180℃ / 1.5h + 200℃ / 1h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 13.36 kJ / m². 2 Its bending strength is 127 MPa.

[0119] Comparative Example 3

[0120] A high-strength bismaleimide resin material comprising the following components in parts by weight:

[0121] The mixture comprises 55 parts of bismaleimide resin, 44 parts of allyl compound, 1.7 parts of modified graphene, and 0.3 parts of dispersion filler; the dispersion filler consists of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of 1:0.5.

[0122] The method for preparing a high-strength bismaleimide resin material includes the following steps:

[0123] (1) Mix the bismaleimide resin and allyl compound evenly, and prepolymerize at 130°C until the solution is transparent to obtain the prepolymer;

[0124] (2) Add the dispersing filler to the prepolymer and stir for 15 min; then add the modified graphene and stir for 15 min to obtain the mixture;

[0125] (3) Pour the mixture into a mold, degas under vacuum for 20 minutes, and then cure by heating at 150℃ / 1h + 160℃ / 1.5h + 180℃ / 1.5h + 200℃ / 1h to obtain a high-strength bismaleimide resin material. Its impact strength was tested to be 12.61 kJ / m². 2 Its bending strength is 143 MPa.

[0126] As can be seen from the above examples and comparative examples, the addition of a certain amount of modified tetra-needle zinc oxide whiskers and modified inorganic nanoparticles in this invention effectively solves the problem of graphene agglomeration. The tetra-needle zinc oxide whiskers have an isotropic spatial distribution, avoiding the possibility of orientation along the stress direction during processing, thus ensuring the isotropic nature of the prepared composite material. Simultaneously, the addition of a small amount of particulate inorganic nanoparticles facilitates their distribution between graphene sheets, preventing agglomeration between graphene sheets during blending. Specifically, the tetra-needle zinc oxide whiskers macroscopically promote the dispersion of graphene with a large sheet structure, ensuring its uniform dispersion within the bismaleimide resin matrix, while the inorganic nanoparticles act as lubricants and separators, preventing agglomeration between graphene sheets in small areas. The addition of graphene composite reinforcing fillers improves both the rigidity and toughness of the composite material. Specifically, compared to Example 10, Comparative Examples 1 and 2 lacked modified tetra-needle zinc oxide whiskers and modified inorganic nanoparticles, respectively, and therefore could not form an isolation structure with graphene, thus failing to promote graphene dispersion and resulting in a decrease in the mechanical properties of the composite material. In Comparative Example 3, the dispersant filler consisted of modified inorganic nanoparticles and modified tetra-needle zinc oxide whiskers in a mass ratio of 1:0.5. The amount of whiskers was small, while the amount of inorganic nanoparticles was excessive. Although the flexural strength of the composite material did not change significantly, its impact toughness was greatly reduced, failing to meet the application requirements.

[0127] The above embodiments illustrate the principles and effects of the present invention and demonstrate its inventive features. Without departing from the principles of the present invention, those skilled in the art can make various modifications and substitutions based on the described disclosure and suggestions of the present invention. Therefore, the scope of protection of the present invention is defined as in the appended claims.

Claims

1. A high-strength bismaleimide resin material, characterized in that, It contains the following components in parts by weight: The composition includes 50-60 parts of bismaleimide resin, 40-50 parts of allyl compound, 1-3 parts of modified graphene, and 0.1-0.5 parts of dispersion filler; the dispersion filler is composed of modified inorganic nanoparticles and modified tetraneedle-shaped zinc oxide whiskers in a mass ratio of (0.1-1):

1. The modified graphene is graphene containing active polar groups; The modified inorganic nanoparticles are inorganic nanoparticles containing active polar groups; the modified tetra-needle zinc oxide whiskers are tetra-needle zinc oxide whiskers containing active polar groups. The active polar group is one or more of amino, epoxy, hydroxy, carboxyl, cyanate, and maleimide groups; The inorganic nanoparticles are nano-silica.

2. The high-strength bismaleimide resin material as described in claim 1, characterized in that, The inorganic nanoparticles have an average particle size of 10-100 nm.

3. A method for preparing a high-strength bismaleimide resin material according to any one of claims 1-2, characterized in that, Includes the following steps: (1) Mix the bismaleimide resin and allyl compound evenly, and heat to prepolymerize until the solution is transparent to obtain the prepolymer; (2) Add modified graphene and dispersing filler to the prepolymer, mix evenly to obtain a mixture; (3) Pour the mixture into a mold, degas under vacuum, and heat to cure, and you will get a high-strength bismaleimide resin material.

4. The method for preparing a high-strength bismaleimide resin material as described in claim 3, characterized in that, The heating temperature is 120-140℃.

5. The method for preparing a high-strength bismaleimide resin material as described in claim 3, characterized in that, The defoaming time is 10-30 minutes.

6. The method for preparing a high-strength bismaleimide resin material as described in claim 3, characterized in that, The heating and curing process is as follows: 145-155℃ / 1-1.5h + 155-165℃ / 1-1.5h + 175-185℃ / 1-1.5h + 195-205℃ / 1-1.5h.