CN111793323A

CN111793323A - Thermosetting resin-based aramid fiber composite material and preparation method thereof

Info

Publication number: CN111793323A
Application number: CN202010275719.1A
Authority: CN
Inventors: 朱波; 黄振振; 范碧波; 何勇
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2020-04-09
Filing date: 2020-04-09
Publication date: 2020-10-20

Abstract

The invention relates to a thermosetting resin-based aramid fiber composite material, which comprises the following components in percentage by weight: (a) the surface of the aramid fiber fabric is coated with a sizing agent, and the aramid fiber fabric is a multi-layer woven bidirectional fabric, a unidirectional fabric, a non-woven fabric or a three-dimensional knitted fabric; and (b) a cured thermosetting resin; wherein the cured thermosetting resin (b) is formed from curing an impregnating thermosetting resin system impregnated in the aramid fiber fabric (a); and based on the total volume of the impregnated aramid fiber fabric (a), the thermosetting resin system for impregnation accounts for 10-80 vol%. The structural general formula of the sizing agent coated on the surface of the aramid fiber fabric (a) is as follows:

the method has the advantages of simple operation, mild condition, easy processing, low cost and the like, and the obtained composite material has good performance, stability and uniformity. The sizing agent can form an interface layer with strong bonding property between the aramid fiber and the matrix resin, can greatly improve the shear strength between the aramid fiber and the matrix resin, and is a method with great potential.

Description

Thermosetting resin-based aramid fiber composite material and preparation method thereof

Technical Field

The invention belongs to the field of composite materials, relates to a thermosetting resin-based composite material, and particularly relates to a preparation method of a continuous aramid fiber reinforced epoxy resin composite material.

Background

The aramid fiber composite material has wide application prospect, and has excellent performances of high tensile strength, high tensile modulus, low density, shock absorption, wear resistance, impact resistance, fatigue resistance, stable size and the like. Meanwhile, the composite material also has outstanding thermal properties of good chemical corrosion resistance, heat resistance, low expansion, low heat conduction and the like and excellent dielectric properties. The aramid fiber has a modulus far greater than that of glass fiber and steel wire, has a low density, is about 40% lighter than glass fiber and about 20% lighter than typical carbon fiber, and has an irreplaceable effect in the use of aerospace materials.

The interface between the fiber and the resin plays a very critical role in the mechanical properties of the composite material, in particular. However, it is known from the aramid fiber structure that since the amide groups on the molecular structure are separated and form pi conjugation effect with the benzene ring, the internal rotation energy is high, the molecular chain links are planar rigid extended chains, the molecular symmetry is high, and the degree of orientation and the degree of crystallinity are high. Due to the strong steric hindrance of the benzene ring, the reactivity of hydrogen atoms on amide groups is poor, so that the aramid fiber surface lacks active groups, the bonding strength of the aramid fiber and the epoxy resin interface is low, the interlaminar shear strength is poor, and the application of the composite material is limited finally.

The mechanical properties of the aramid fiber composite material are good and bad depending on whether the aramid fiber can well transfer stress or not and whether a good interface exists or not. When the structural composite material is damaged by stress, the interface bonding force between the aramid fiber and the epoxy resin is maximized as far as possible on the premise that the fiber is pulled out.

Therefore, in order to realize the preparation of the high-performance aramid composite material, a composite material preparation system with excellent interface performance needs to be developed urgently.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provide a thermosetting resin-based aramid composite material.

The second purpose of the invention is to provide a preparation method of the composite material. The composite material prepared by the method has excellent interface performance.

In order to achieve the purpose, the invention adopts the following technical scheme:

the thermosetting resin-based aramid fiber composite material is characterized by comprising modified aramid fiber coated with a sizing agent and thermosetting resin, wherein the aramid fiber coated with the sizing agent in the composite material has the volume content of 10-80%; the structural general formula of the sizing agent is as follows:

wherein: m and n are positive integers, m is more than or equal to 1 and less than or equal to 5000, n is more than or equal to 1 and less than or equal to 5000, m: n is 1: 99-99: 1;

R₁comprises the following steps:-NH₂、-COOH、-OH、-SH、

any one of the above;

R₂，R₃，R₄independently of one another, -H, -CH₃、-NH₂Any one of-OH, -COOH and-SH;

R₅comprises the following steps: -H, -CH₃

L₁Is any one of-NH-and-O-;

L₂is composed of

Any one of the above; a and b are positive integers, a is more than or equal to 0 and less than or equal to 12, and b is more than or equal to 0 and less than or equal to 3.

The aramid fiber coated with the sizing agent in the composite material has the volume content of 10-80%

The ratio of m to n is 1: 99-99: 1.

The thermosetting resin is phenolic resin, epoxy resin, polyurethane, polyimide, bismaleimide or cyanate resin.

R in the above general formula₁is-NH₂Any one of, -COOH, -OH, -SH or epoxy group.

R in the above general formula₂，R₃，R₄is-H, -CH₃、-NH₂-OH, -COOH or-SH.

R in the above general formula₅is-H, -CH₃。

In the above general formula L₁is-NH-, -O-.

In the above general formula L₂Is composed of

A method for preparing the thermosetting resin-based aramid composite material is characterized by comprising the following specific steps:

a. mixing a compound containing a dihydroxy benzene group and methacrylic anhydride according to a molar ratio of 1: 1-1: 2 to obtain a monomer of the modified methacrylamide, wherein the structural formula of the monomer is as follows:

the structural formula of the compound containing the dihydroxyphenyl group is as follows:

b. b, carrying out free radical polymerization reaction on the modified methacrylamide monomer obtained in the step a and a modified acrylic monomer in the presence of an initiator to obtain a surface modifier; the structural formula of the modified methacrylic or acrylic monomer is as follows:

c. and (c) coating the surface modifier obtained in the step (b) on the surface of the aramid fiber, drying at 100-130 ℃, and then collecting the filaments.

d, (i) providing an aramid fiber fabric coated with a sizing agent on the surface, wherein the aramid fiber fabric is a woven bidirectional fabric, a unidirectional fabric, a non-woven fabric or a three-dimensional woven fabric;

(ii) impregnating said aramid fiber fabric with a thermosetting resin system for impregnation to obtain an impregnated aramid fiber fabric layer; cutting the impregnated aramid fiber fabric layer into a size the same as that of the mold, and stacking 1-50 layers to manufacture a prefabricated product; loading the prefabricated product into a mold, and closing the mold; finally, manufacturing the composite material by using methods of oven curing, autoclave curing, compression molding, resin transfer molding and vacuum auxiliary forming; or

(iii) preparing the aramid fiber fabric into a preformed body, arranging the preformed body in a forming mould, and finally manufacturing the composite material by a resin transfer molding or vacuum auxiliary forming method.

The specific steps of the step a are as follows: taking 8g to 12g of Na₂B₄O₇,3.2g～4.8g NaHCO₃Adding the mixture into a reaction eggplant bottle, then adding 80ml to 120ml of ultrapure water, and then adding 5g to 7g of a compound containing a dihydroxyphenyl group; then 3.8ml to 5.6ml of methacrylic anhydride is dissolved in 20ml to 30ml of THF and is added into the solution drop by drop; then preparing a NaOH solution with the concentration of 0.8-1.2 mol/L, dropwise adding the NaOH solution into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reaction for 13-21 hours; after the reaction is finished, adding 40-60 ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 1-3 times; dropwise adding HCl solution with the concentration of 4.8-7.2 mol/L into the filtrate to adjust the pH value to 1.5-2.5; then transferring the filtrate to a round-bottom flask, adding 40-60 ml of ethyl acetate, and extracting for 1-2 times; finally precipitating into cold 400-600 ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain the modified methacrylamide monomer.

The above-mentioned compound containing a dihydroxyphenyl group is: methyldopa, norepinephrine, dopamine, droxidopa, methyldopamine, or 5-hydroxydopamine.

The specific steps of the step b are as follows: free radical polymerization is adopted, the reaction condition is photo-initiation or thermal initiation, 0.5g to 0.75g of initiator, 0.025g to 2.810g of modified methacrylamide monomer and 0.0129g to 2.260g of modified methacrylic acid monomer or acrylic acid monomer are added into a reaction tube, the polymerization reaction is carried out for 0.5h to 24h under the environment of inert gas at the temperature of 25 ℃ to 100 ℃ or the environment of ultraviolet illumination (the wavelength is 100nm to 380nm) at the temperature of 0 ℃ to 40 ℃, the solid part obtained by the reaction is dissolved in 10ml to 30ml of methanol solution, then the solution is titrated into 100ml to 500ml of cold anhydrous ether for precipitation and purification, the insoluble substance is centrifugally collected at 3000rpm to 10000rpm, and the obtained precipitation product is placed on a vacuum line for vacuum drying overnight to obtain the final bionic polymer.

The modified methacrylic acid monomer is 2-aminoethyl methacrylate, 2-aminoethyl methacrylamide, methacrylic acid, methacrylamide, glycidyl methacrylate, hydroxyethyl methacrylate or methyl methacrylate.

The modified acrylic monomer is hydroxyethyl acrylate.

The thermal initiator is azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, azobisisobutylamidine hydrochloride or dibenzoyl peroxide.

The photoinitiator is benzoin, benzoin dimethyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, diphenyl ethyl ketone, thiopropoxy thioxanthone, benzophenone or thiopropoxy thioxanthone.

The concrete steps of the step c are as follows: dissolving a sizing agent in a buffer solution with the pH value of 1-8 to prepare a sizing solution with the concentration of 0.01-100 mg/ml, soaking the pretreated fiber in the solution for 0.1-1000 s, taking out the fiber, soaking the fiber in deionized water for 0.1-1000 s, taking out the fiber, putting the fiber in an oven for drying at 100-130 ℃ for 1-3 h, and obtaining the modified fiber.

The concrete steps of the step d are as follows: vacuumizing at room temperature to a vacuum degree of not less than-0.095 MPa to-0.120 MPa, heating at a rate of 0.5-2.0 ℃/min, and pressurizing at room temperature to 70-90 ℃ to 0.4-0.7 MPa; continuously heating to 130-150 ℃, and keeping the temperature for 1-1.5 h; continuously heating to 170-190 ℃, preserving the heat for 2-3 h, and cooling to 40-60 ℃ at a speed of not more than 1 ℃/min.

Compared with the prior art, the method has the advantages of simple operation, mild conditions, easy processing, low cost and the like, and also ensures excellent interface bonding performance of the thermosetting resin epoxy resin, so that the composite material has good, stable and uniform performance. The method can form an interface layer with strong bonding property between the aramid fiber and the resin, can greatly improve the shear strength between the aramid fiber and the resin interface, and is a method with great potential.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 shows the result of a sizing agent 2 sizing aramid fiber and epoxy resin monofilament pull-out test;

figure 2 sizing agent 2 sized aramid, untreated aramid and epoxy a) flexural strength and b) interlaminar shear strength test results.

Detailed Description

In order to make the invention more comprehensible, preferred embodiments are described in detail below.

The aramid fiber volume content determination method comprises the following steps: weighing aramid fiber as M₁Drying the prepared wet prepreg until the mass does not change any more, weighing the prepreg and subtracting the mass of aramid fiber to obtain the mass of the epoxy resin, and recording the mass as M₂And aramid density is denoted as ρ₁Density of epoxy resin is denoted as ρ₂Then volume content V of aramid fiber₁The% is calculated as:

monofilament pull-out test: before sample preparation, aramid fiber is firstly immersed into acetone for ultrasonic cleaning for 1h, then is washed clean by deionized water, and then is dried at 100 ℃ for standby. And (3) preparing the epoxy resin and the curing agent according to the ratio of 2:1, fixing the cleaned aramid fiber on a mold, dropwise adding the prepared numerical value on the aramid fiber monofilament, and curing at 60 ℃ for 1h to obtain a sample. The test was carried out using a monofilament yarn tensile elongation tester C (XQ-1A) manufactured by Shanghai New fiber Instrument Co., Ltd., at a loading rate of 2 mm/min.

Experimental materials

Example 1

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5g of II-1; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then dropwise adding 6M HCl to the filterAdjusting the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 5.6g of modified methacrylamide monomer (III-1) with the yield of 80%.

(B) Polymerization: by radical polymerization, 0.5g of AIBN, 2.21g (10mmol) of modified methacrylamide monomer (III-1) and 0.0129g (0.1mmol) of modified methacrylic acid monomer (IV-1) were added to a reaction tube, polymerization was carried out at room temperature under an inert gas atmosphere for 16 hours, the solid portion obtained by the reaction was dissolved in 10ml of methanol solution, and then titrated into 100ml of cold anhydrous ether to precipitate for purification, the insoluble matter was collected by centrifugation at 3000rpm, and the obtained precipitate was placed on a vacuum line and vacuum-dried overnight to obtain 2.01g of surface modifier I-1. The molar ratio of the III-1 unit to the IV-1 unit in the surface modifier I-1 is 99: 1.

(C) fiber sizing: weighing 0.1g of sizing agent I-1, dissolving in 100ml of acetic acid buffer solution with the pH value of 5.5, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 100 ℃ for 3h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 0.1%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through 25% of epoxy resin acetone solution on fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and implementing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 0.5 deg.C/min, heating to 80 deg.C, and pressurizing at 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 3mm, wherein the volume fraction of the aramid fiber is 50%, the interlaminar shear strength of the composite material is 54.20MPa, and is improved by 88% compared with that of a comparative example 1(28.85 MPa).

Example 2

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 6.9g of II-2; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 7.1g of modified methacrylamide monomer (III-2), wherein the yield is 82%.

(B) Polymerization: by adopting free radical polymerization, 0.5g of AIBNB, 1.422g (6mmol) of modified methacrylamide monomer (III-2) and 0.0128g (0.1mmol) of modified methacrylic acid monomer (IV-2) are added into a reaction tube, polymerization reaction is carried out for 16h under the environment of inert gas at room temperature, the solid part obtained by the reaction is dissolved in 10ml of methanol solution, then titration is carried out to 100ml of cold anhydrous ether for precipitation and purification, insoluble substances are collected by centrifugation at 3000rpm, and the obtained precipitation product is placed on a vacuum line for vacuum drying overnight to obtain 1.2g of surface modifier I-2. By passing¹H-NMR measurement shows that the molar ratio of the III-2 unit to the IV-2 unit in the surface modifier I-2 is 98: 2.

(C) fiber sizing: weighing 0.15g of sizing agent I-2, dissolving in 100ml of acetic acid buffer solution with the pH value of 5.5, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 100 ℃ for 3h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 0.5%. The fibers were tested for monofilament pull-out and the results are shown in figure 1.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 30% epoxy resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 0.5 deg.C/min, heating to 80 deg.C, and pressurizing at 0.6 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 3mm, wherein the volume fraction of the aramid fiber is 60%, the interlaminar shear strength of the composite material is 63.70MPa, and is improved by 103% compared with that of comparative example 2(31.37MPa), as shown in FIG. 2.

Example 3

(A) Synthesis of modified methacrylamide monomer: take 8g of Na₂B₄O₇，3.2g NaHCO₃Adding into a reaction eggplant bottle, then adding 80ml of ultrapure water, and then adding 5.4g of II-3; then 3.8ml of methacrylic anhydride is dissolved in 20ml of THF and is added into the solution drop by drop; then 0.8M NaOH is prepared and is added into the solution drop by drop, the pH value is adjusted to 8, nitrogen is introduced into the solution at room temperature, and the solution is magnetically stirred and reacts for 13 hours; after the reaction is finished, adding 40ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 1 time; then 4.8M HCl is added into the filtrate dropwise to adjust the pH value to 1.5; then transferring the filtrate to a round-bottom flask, adding 40ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 400ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 6.1g of modified methacrylamide monomer (III-3), wherein the yield is 85%.

(B) Polymerization: by adopting free radical polymerization, 0.5g of AIBNB, 2.81g (10mmol) of modified methacrylamide monomer (III-3) and 0.0284g (0.2mmol) of modified methacrylic acid monomer (IV-3) are added into a reaction tube, polymerization reaction is carried out for 0.5h under the environment of 100 ℃ inert gas, the solid part obtained by the reaction is dissolved in 10ml of methanol solution, then titration is carried out to 100ml of cold anhydrous ether for precipitation for purification, centrifugation at 3000rpm is carried out to collect insoluble substances, and the obtained precipitate product is placed on a vacuum line for vacuum drying overnight to obtain 2.4g of biomimetic polymer I-3. The molar ratio of the III-3 unit to the IV-3 unit in I-3 in the polymer, as determined by 1H-NMR, was 97: 3.

(C) fiber sizing: weighing 0.1g of sizing agent I-3, dissolving in 100ml of acetic acid buffer solution with the pH value of 5.5, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 100 ℃ for 3h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 0.1%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 30% epoxy resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting 20 x 20cm prepreg cloth according to the shape of a mold to carry out unidirectional laying, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.120 MPa, heating at 0.5 deg.c/min, and pressurizing at 70 deg.c to 0.4 MPa; continuously heating to 160 ℃, preserving the heat for 2h, and cooling to below 40 ℃ at the speed of 0.2 ℃/min. The thickness of the obtained composite plate is 3mm, wherein the volume fraction of the aramid fiber is 60%, the interlaminar shear strength of the composite material is 64.35MPa, and is improved by 98% compared with that of a comparative example 3(32.54 MPa).

Example 4

(A) Synthesis of modified methacrylamide monomer: collecting 12g of Na₂B₄O₇，4.8g NaHCO₃Adding into a reaction eggplant bottle, then adding 120ml of ultrapure water, and then adding 6.4g of II-4; then 5.6ml of methacrylic anhydride is dissolved in 30ml of THF and is added into the solution drop by drop; then preparing 1.2M NaOH, dropwise adding the NaOH solution into the solution, adjusting the pH to 9, introducing nitrogen at room temperature, and magnetically stirring for reaction for 21 hours; after the reaction is finished, adding 60ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 3 times; then 7.2M HCl is added into the filtrate dropwise to adjust the pH value to 2.5; then transferring the filtrate to a round-bottom flask, adding 60ml of ethyl acetate, and extracting for 2 times; finally precipitating into cold 600ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 6.8g of modified methacrylamide monomer (III-4), wherein the yield is 83%.

(B) Polymerization: by adopting free radical polymerization, adding 0.5g of AIBNB, 1.782g (6mmol) of modified methacrylamide monomer (III-4) and 0.0284g (0.2mmol) of modified methacrylic acid monomer (IV-4) into a reaction tube, carrying out polymerization reaction for 0.5h at 100 ℃ in an inert gas environment, dissolving the solid part obtained by the reaction in 30ml of methanol solution, titrating the solution into 500ml of cold anhydrous ether for precipitation for purification, centrifuging at 10000rpm to collect insoluble substances, and putting the obtained precipitate on a vacuum line for vacuumizing and drying overnight to obtain 1.523g of biomimetic polymer I-4. The molar ratio of the III-4 units to the IV-4 units in I-4 in the polymer, determined by 1H-NMR, was 95: 5.

(C) fiber sizing: weighing 0.2g of sizing agent I-4, dissolving in 100ml of acetic acid buffer solution with the pH value of 5.5, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 100 ℃ for 3h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 35% epoxy resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 100 deg.C, and pressurizing at 0.7 MPa; continuously heating to 200 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 3mm, wherein the volume fraction of the aramid fiber is 70%, the interlaminar shear strength of the composite material is 65.55MPa, and the interlaminar shear strength is improved by 90% compared with that of a comparative example 4(34.57 MPa).

Example 5

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 7.0g of II-5; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 9.1g of modified methacrylamide monomer (III-5), wherein the yield is 82%.

(B) Polymerization: by adopting free radical polymerization, adding 0.5g of AIBNB, 2.35g (10mmol) of modified methacrylamide monomer (III-5) and 0.065g (0.5mmol) of modified methacrylic acid monomer (IV-5) into a reaction tube, carrying out polymerization reaction for 16h under the environment of inert gas at room temperature, dissolving the solid part obtained by the reaction in 30ml of methanol solution, titrating the solution into 500ml of cold anhydrous ether for precipitation for purification, centrifuging at 10000rpm to collect insoluble substances, and putting the obtained precipitate on a vacuum line for vacuumizing and drying overnight to obtain 2.2g of surface modifier I-5. The molar ratio of the III-5 unit to the IV-5 unit in the surface modifier I-5, as determined by 1H-NMR, was 91: 9.

(C) fiber sizing: weighing 0.25g of sizing agent I-5, dissolving in 100ml of acetic acid buffer solution with the pH value of 5.5, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 100 ℃ for 3h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 2.5%.

(D) Preparing a composite material: a thermosetting resin-base composite material is prepared through spreading the reinforcing aramid fibres in a closed mould, injecting 35% solution of epoxy resin in acetone under pressure, immersing said reinforcing aramid fibres in it, solidifying and demoulding. The curing process comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 10mm, wherein the volume fraction of the aramid fiber is 50%, the interlaminar shear strength of the composite material is 55.89MPa, and is improved by 63% compared with that of a comparative example 5(34.28 MPa).

Example 6

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5.5g of II-6; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; knot to be reactedAdding 50ml of ethyl acetate into the reaction solution after the reaction, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 7.5g of modified methacrylamide monomer (III-6), wherein the yield is 87%.

(B) Polymerization: by adopting free radical polymerization, 0.5g of AIBNB, 1.185g (5mmol) of modified methacrylamide monomer (III-6) and 0.0128g (1mmol) of modified methacrylic acid monomer (IV-6) are added into a reaction tube, polymerization reaction is carried out for 16h under the inert gas environment at the temperature of 30 ℃, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, the solution is titrated into 200ml of cold anhydrous ether for precipitation and purification, insoluble substances are collected by centrifugation at 8000rpm, and the obtained precipitation product is placed on a vacuum line for vacuum drying overnight to obtain 1.6g of surface modifier I-6. The molar ratio of the III-6 unit to the IV-6 unit in the surface modifier I-6, as determined by 1H-NMR, was 83: 17.

(C) fiber sizing: weighing 0.3g of sizing agent I-6, dissolving in 100ml of acetic acid buffer solution with the pH value of 5.5, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 100 ℃ for 3h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 3%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 35% epoxy resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an oven curing molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 4mm, wherein the volume fraction of the aramid fiber is 80%, the interlaminar shear strength of the composite material is 57.66MPa, and the interlaminar shear strength is improved by 63% compared with that of a comparative example 6(35.3 MPa).

Example 7

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5.5g of II-7; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 6.1g of modified methacrylamide monomer (III-7) with the yield of 88%.

(B) Polymerization: by adopting free radical polymerization, 0.5g of AIBNB, 0.891g (5mmol) of modified methacrylamide monomer (III-7) and 0.145g (1mmol) of modified methacrylic acid monomer (IV-7) are added into a reaction tube, polymerization reaction is carried out for 16h under the inert gas environment at the temperature of 30 ℃, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, the solution is titrated into 200ml of cold anhydrous ether for precipitation and purification, insoluble substances are collected by centrifugation at 8000rpm, and the obtained precipitation product is placed on a vacuum line and dried by vacuum pumping overnight to obtain 0.8g of surface modifier I-7. The molar ratio of the III-7 unit to the IV-7 unit in the surface modifier I-7 as determined by 1H-NMR was 67: 33.

(C) fiber sizing: weighing 0.25g of sizing agent I-7, dissolving in 100ml of acetic acid buffer solution with the pH value of 5.5, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 100 ℃ for 3h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1.5%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through 25% of polyurethane solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 4mm, wherein the volume fraction of the aramid fiber is 70%, the interlaminar shear strength of the composite material is 48.88MPa, and the interlaminar shear strength is improved by 36% compared with that of a comparative example 7(35.97 MPa).

Example 8

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5g of II-8; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 5.6g of modified methacrylamide monomer (III-8) with the yield of 80%.

(B) Polymerization: by adopting free radical polymerization, 0.5g of AIBNB, 1.335g (5mmol) of modified methacrylamide monomer (III-8) and 0.89g (5mmol) of modified methacrylic acid monomer (IV-8) are added into a reaction tube, polymerization reaction is carried out for 16h under the inert gas environment at the temperature of 30 ℃, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, the methanol solution is titrated into 200ml of cold anhydrous ether for precipitation and purification, insoluble substances are collected by centrifugation at 8000rpm, and the obtained precipitation product is placed on a vacuum line for vacuum drying overnight to obtain 1.9g of surface modifier I-8. The molar ratio of the III-8 unit to the IV-8 unit in the surface modifier I-8, as determined by 1H-NMR, was 50: 50.

(C) fiber sizing: weighing 0.25g of sizing agent I-8, dissolving in 100ml of acetic acid buffer solution with the pH value of 5.5, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 100 ℃ for 3h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1.5%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 35% polyurethane acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 4mm, wherein the volume fraction of the aramid fiber is 70%, the interlaminar shear strength of the composite material is 52.33MPa, and is improved by 35% compared with that of a comparative example 8(38.76 MPa).

Example 9

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5g of II-9; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 5.6g of modified methacrylamide monomer (III-1) with the yield of 70%.

(B) Polymerization: by adopting light-initiated polymerization, 0.75g of DMPAI, 1.325g (5mmol) of modified methacrylamide monomer (III-9) and 1.57g (10mmol) of modified methacrylic acid monomer (IV-9) are added into a reaction tube, the polymerization reaction is carried out for 16h under the environment of ultraviolet irradiation inert gas with the temperature of 0 ℃ and the wavelength of 256nm, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, then the methanol solution is titrated into 200ml of cold anhydrous ether for precipitation for purification, the insoluble substance is centrifugally collected at 8000rpm, and the obtained precipitate product is placed on a vacuum line for vacuumizing and drying overnight to obtain 2.1g of the biomimetic polymer I-9. The molar ratio of the III-9 units to the IV-9 units in I-9 in the polymer, determined by 1H-NMR, was 33: 67.

(C) fiber sizing: weighing 0.25g of sizing agent I-9, dissolving in 100ml of acetic acid buffer solution with the pH value of 5.5, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 100 ℃ for 3h to obtain the modified glass fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1.5%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through 25% of cyanate ester resin acetone solution on fibers obtained in the previous step, drying the prepreg until the quality does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 4mm, wherein the volume fraction of the aramid fiber is 50%, the interlaminar shear strength of the composite material is 57.58MPa, and is improved by 79% compared with that of comparative example 9(32.17 MPa).

Example 10

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5g of II-10; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 5.6g of modified methacrylamide monomer (III-1), wherein the yield is 85%.

(B) Polymerization: by adopting light-initiated polymerization, 0.75g of DMPA0, 0.269g (1mmol) of modified methacrylamide monomer (III-10) and 0.468g (3mmol) of modified methacrylic acid monomer (IV-10) are added into a reaction tube, the polymerization reaction is carried out for 16h under the environment of 365nm ultraviolet illumination inert gas at the temperature of 40 ℃, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, the methanol solution is titrated into 200ml of cold anhydrous ether for precipitation for purification, the insoluble substance is centrifugally collected at 8000rpm, and the obtained precipitate product is placed on a vacuum line for vacuumizing and drying overnight to obtain 0.5g of the biomimetic polymer I-10. The molar ratio of the III-10 units to the IV-10 units in I-10 in the polymer, determined by 1H-NMR, was 25: 75.

(C) fiber sizing: weighing 0.25g of sizing agent I-10, dissolving in 100ml of acetic acid buffer solution with the pH value of 5.5, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 100 ℃ for 3h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1.5%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through 35% of cyanate ester resin acetone solution on fibers obtained in the previous step, drying the prepreg until the quality does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 5mm, wherein the volume fraction of the aramid fiber is 70%, the interlaminar shear strength of the composite material is 60.54MPa, and the interlaminar shear strength is improved by 65% compared with that of a comparative example 10(36.79 MPa).

Example 11

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5g of II-11; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, adding into the solution dropwise, adjusting pH 8E9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of n-hexane, carrying out suction filtration, taking filter residue, and drying to obtain 5.6g of modified methacrylamide monomer (III-11) with the yield of 81%.

(B) Polymerization: by using light-initiated polymerization, 0.75g of DMPAI, 0.556g (2mmol) of modified methacrylamide monomer (III-11) and 1.248g (8mmol) of modified methacrylic acid monomer (IV-11) are added into a reaction tube, polymerization reaction is carried out for 16h under the inert gas environment at 40 ℃, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, then titration is carried out to 200ml of cold anhydrous ether for precipitation for purification, insoluble substances are collected by centrifugation at 8000rpm, and the obtained precipitation product is placed on a vacuum line for vacuum drying overnight to obtain 1.3g of surface modifier I-11. The molar ratio of the III-11 unit to the IV-11 unit in the surface modifier I-11, as determined by 1H-NMR, was 17: 83.

(C) fiber sizing: weighing 0.25g of sizing agent I-11, dissolving in 100ml of acetic acid buffer solution with the pH value of 4, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 8min, and drying the fiber at 120 ℃ for 2h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1.5%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 30% polyimide resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting a 40 cm-by-40 cm unidirectional laying layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 5mm, wherein the volume fraction of the aramid fiber is 50%, the interlaminar shear strength of the composite material is 54.24MPa, and is improved by 68% compared with that of a comparative example 11(32.27 MPa).

Example 12

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 6.9g of II-12; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 7.1g of modified methacrylamide monomer (III-12) with the yield of 80%.

(B) Polymerization: by using light-initiated polymerization, 0.75g of DMPAI, 0.266g (1mmol) of modified methacrylamide monomer (III-12) and 1.085g (7mmol) of modified methacrylic acid monomer (IV-12) are added into a reaction tube, polymerization reaction is carried out for 16h under the inert gas environment at 40 ℃, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, the solution is titrated into 200ml of cold anhydrous ether for precipitation and purification, insoluble substances are collected by centrifugation at 8000rpm, and the obtained precipitate is placed on a vacuum line and dried overnight by vacuum pumping to obtain 1.0g of surface modifier I-2. The molar ratio of the III-12 unit to the IV-12 unit in the surface modifier I-12 as determined by 1H-NMR was 13: 87.

(C) fiber sizing: weighing 0.25g of sizing agent I-12, dissolving in 100ml of acetic acid buffer solution with the pH value of 4, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 8min, and drying the fiber at 120 ℃ for 2h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1.5%.

(D) Preparing a composite material: a thermosetting resin-base composite material is prepared through spreading the reinforcing aramid fibres in the mould cavity of closed mould, injecting the 30% solution of polyimide resin in acetone under pressure, immersing said reinforcing aramid fibres in it, solidifying and demoulding. The curing process comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 200mm, wherein the volume fraction of the aramid fiber is 70%, the interlaminar shear strength of the composite material is 56.76MPa, and is improved by 57% compared with that of a comparative example 12(36.12 MPa).

Example 13

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5.4g of II-13; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 6.1g of modified methacrylamide monomer (III-13) with the yield of 82%.

(B) Polymerization: by adopting light-initiated polymerization, 0.75g of DMPAI, 0.284g (1mmol) of modified methacrylamide monomer (III-13) and 1.42g (10mmol) of modified methacrylic acid monomer (IV-13) are added into a reaction tube, polymerization reaction is carried out for 16h under the inert gas environment at 60 ℃, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, then titration is carried out to 200ml of cold anhydrous ether for precipitation for purification, insoluble substances are collected by centrifugation at 8000rpm, and the obtained precipitation product is placed on a vacuum line for vacuum drying overnight to obtain 2.6g of surface modifier I-13. The molar ratio of the III-13 unit to the IV-13 unit in the surface modifier I-13 is 10: 90.

(C) fiber sizing: weighing 0.25g of sizing agent I-13, dissolving in 100ml of acetic acid buffer solution with the pH value of 4, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 8min, and drying the fiber at 120 ℃ for 2h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1.5%. And then, carrying out monofilament extraction test, wherein the experimental result shows that the interfacial shear strength of the surface modified carbon fiber and the epoxy resin is 13.35 MPa. Coating a layer of surface modifier I-13 on the surface of aramid fiber by an immersion method, and then drying the fiber in vacuum at 120 ℃ for 6 hours to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1.5%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg by passing fibers obtained in the previous step through a 30% bismaleimide resin acetone solution, drying the prepreg until the quality does not change any more, cutting a 40 cm-by-40 cm unidirectional laying layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 0.01mm, wherein the volume fraction of the aramid fiber is 10%, the interlaminar shear strength of the composite material is 26.56MPa, and is improved by 45% compared with that of a comparative example 13(18.28 MPa).

Example 14

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 6.4g of II-14; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of n-hexane, carrying out suction filtration, taking filter residue, and drying to obtain 6.8g of modified methacrylamide monomer (III-14) with the yield of 81%.

(B) Polymerization: by using light-initiated polymerization, 0.75g of DMPAI, 0.156g (0.5mmol) of modified methacrylamide monomer (III-14) and 1.41g (10mmol) of modified methacrylic acid monomer (IV-14) are added into a reaction tube, polymerization reaction is carried out for 16h under the inert gas environment at 60 ℃, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, the solution is titrated into 200ml of cold anhydrous ether for precipitation and purification, insoluble substances are collected by centrifugation at 8000rpm, and the obtained precipitate is placed on a vacuum line and dried by vacuum pumping overnight to obtain 1.2g of surface modifier I-4. The molar ratio of the III-14 unit to the IV-14 unit in the surface modifier I-14 is 5: 95.

(C) fiber sizing: weighing 0.2g of sizing agent I-14, dissolving in 100ml of acetic acid buffer solution with the pH value of 4, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 5min, and drying the fiber at 120 ℃ for 2h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prefabricated product by passing fibers obtained in the last step through a 30% bismaleimide resin acetone solution, drying the prefabricated product until the quality of the prefabricated product is not changed, cutting 40 cm-40 cm unidirectional layering according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting a compression molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 5mm, wherein the volume fraction of the aramid fiber is 70%, the interlaminar shear strength of the composite material is 50.21MPa, and is improved by 66% compared with that of a comparative example 14(30.2 MPa).

Example 15

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 7.0g of II-15; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, the reaction is carried outAdding 50ml ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 9.1g of modified methacrylamide monomer (III-15), wherein the yield is 85%.

(B) Polymerization: by using light-initiated polymerization, 0.75g of DMPAI, 0.056g (0.2mmol) of modified methacrylamide monomer (III-15) and 2.27g (10mmol) of modified methacrylic acid monomer (IV-15) are added into a reaction tube, polymerization reaction is carried out for 16h under the inert gas environment at 60 ℃, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, the solution is titrated into 200ml of cold anhydrous ether for precipitation for purification, insoluble substances are collected by centrifugation at 8000rpm, and the obtained precipitate product is placed on a vacuum line for vacuum drying overnight to obtain 2.2g of the surface modifier I-15. The molar ratio of the III-15 unit to the IV-15 unit in the surface modifier I-15 is 2: 98.

(C) fiber sizing: weighing 0.2g of sizing agent I-15, dissolving in 100ml of acetic acid buffer solution with the pH value of 6, soaking aramid fiber in the solution for 30s, then soaking in deionized water for 10min, and then drying the fiber at 120 ℃ for 2h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 30% phenolic resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting 40cm by 40cm unidirectional paving layers according to the shape of a die, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 0.5 deg.C/min, heating to 80 deg.C, and pressurizing at 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 5mm, wherein the volume fraction of the aramid fiber is 50%, the interlaminar shear strength of the composite material is 54.35MPa, and is improved by 99% compared with that of a comparative example 15(27.37 MPa).

Example 16

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5.5g of II-16; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of n-hexane, carrying out suction filtration, taking filter residue, and drying to obtain 7.5g of modified methacrylamide monomer (III-16), wherein the yield is 86%.

(B) Polymerization: by using light-initiated polymerization, 0.75g of DMPAI, 0.031g (0.1mmol) of modified methacrylamide monomer (III-16) and 2.384g (8mmol) of modified methacrylic acid monomer (IV-16) are added into a reaction tube, polymerization reaction is carried out for 8h under the inert gas environment at 80 ℃, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, the solution is titrated into 200ml of cold anhydrous ether for precipitation and purification, insoluble substances are collected by centrifugation at 8000rpm, and the obtained precipitate is placed on a vacuum line and dried by vacuumizing overnight to obtain 2.1g of surface modifier I-6. The molar ratio of the III-16 unit to the IV-16 unit in the surface modifier I-16 is 1: 99.

(C) fiber sizing: weighing 0.2g of sizing agent I-16, dissolving in 100ml of acetic acid buffer solution with the pH value of 6, soaking aramid fiber in the solution for 60s, then soaking in deionized water for 10min, and then drying the fiber at 130 ℃ for 1h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1%. And then, carrying out monofilament extraction test, wherein the experimental result shows that the interfacial shear strength of the surface modified polyester fiber and the epoxy resin is 17.56 MPa. Coating a layer of surface modifier I-16 on the surface of aramid fiber by an immersion method, and then drying the fiber in vacuum at 120 ℃ for 6 hours to obtain the modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 30% phenolic resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting 40cm by 40cm unidirectional paving layers according to the shape of a die, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.6 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 5mm, wherein the volume fraction of the aramid fiber is 50%, the interlaminar shear strength of the composite material is 55.34MPa, and is improved by 93% compared with that of a comparative example 16(28.67 MPa).

Example 17

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5.5g of II-17; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of n-hexane, carrying out suction filtration, taking filter residue, and drying to obtain 6.1g of modified methacrylamide monomer (III-17) with the yield of 81%.

(B) Polymerization: by using photo-initiated polymerization, ABVN0.75g, 0.0626g (0.2mmol) of modified methacrylamide monomer (III-17) and 2.98g (8mmol) of modified methacrylic acid monomer (IV-17) were added to a reaction tube, polymerization was carried out for 8 hours at room temperature under an inert gas atmosphere, the solid portion obtained by the reaction was dissolved in 20ml of methanol solution, further titrated into 200ml of cold anhydrous ether for precipitation for purification, the insoluble matter was collected by centrifugation at 8000rpm, and the obtained precipitate was placed on a vacuum line and dried overnight under vacuum to obtain 2.5g of surface modifier I-17. The molar ratio of the III-17 units to the IV-17 units in the surface modifier I-17, as determined by 1H-NMR, was 2: 98.

(C) fiber sizing: weighing 0.2g of sizing agent I-17, dissolving in 100ml of acetic acid buffer solution with the pH value of 6, soaking aramid fiber in the solution for 60s, then soaking in deionized water for 10min, and then drying the fiber at 130 ℃ for 1h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 1%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 30% phenolic resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting 40cm by 40cm unidirectional paving layers according to the shape of a die, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.6 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 3mm, wherein the volume fraction of the aramid fiber is 60%, the interlaminar shear strength of the composite material is 56.82MPa, and is improved by 93% compared with that of a comparative example 17(29.41 MPa).

Example 18

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5g of II-18; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; after the reaction is finished, adding 50ml of ethyl acetate into the reaction solution, standing for layering, taking the lower-layer water phase, and repeating for 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of normal hexane, carrying out suction filtration, taking filter residue, and drying to obtain 5.6g of modified methacrylamide monomer (III-18) with the yield of 80%.

(B) Polymerization: by adopting photo-initiated polymerization, 0.75g of ABVN, 0.0269g (0.1mmol) of modified methacrylamide monomer (III-18) and 1.925g (8mmol) of modified methacrylic acid monomer (IV-18) are added into a reaction tube, polymerization reaction is carried out for 24h under the environment of inert gas at room temperature, the solid part obtained by the reaction is dissolved in 20ml of methanol solution, then the solution is titrated into 200ml of cold anhydrous ether for precipitation and purification, insoluble substances are collected by centrifugation at 8000rpm, and the obtained precipitation product is placed on a vacuum line for vacuum drying overnight to obtain 1.5g of surface modifier I-18. The molar ratio of the III-18 unit to the IV-18 unit in I-18 in the surface modifier is 1: 99.

(C) fiber sizing: weighing 0.1g of sizing agent I-18, dissolving in 200ml of acetic acid buffer solution with the pH value of 6, soaking aramid fiber in the solution for 60s, then soaking in deionized water for 10min, and drying the fiber at 130 ℃ for 1h to obtain the modified fiber with the mass fraction of the surface modifier of 0.01%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 30% phenolic resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting 40cm by 40cm unidirectional paving layers according to the shape of a die, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 3mm, wherein the volume fraction of the aramid fiber is 60%, the interlaminar shear strength of the composite material is 58.35MPa, and is improved by 93% compared with that of a comparative example 18(30.2 MPa).

Example 19

(A) Synthesis of modified methacrylamide monomer: 10g of Na was taken₂B₄O₇，4g NaHCO₃Adding into a reaction eggplant bottle, then adding 100ml of ultrapure water, and then adding 5g of II-19; then 4.7ml of methacrylic anhydride is dissolved in 25ml of THF and is added into the solution drop by drop; then preparing 1M NaOH, dropwise adding the NaOH into the solution, adjusting the pH to 8-9, introducing nitrogen at room temperature, and magnetically stirring for reacting for 17 hours; adding 50ml ethyl acetate into the reaction solution after the reaction is finished, standing for layering, and taking downThe aqueous phase was layered and repeated 2 times; then 6M HCl is added into the filtrate dropwise to adjust the pH value to 2; then transferring the filtrate to a round-bottom flask, adding 50ml of ethyl acetate, and extracting for 3 times; finally precipitating into cold 500ml of n-hexane, carrying out suction filtration, taking filter residue, and drying to obtain 5.6g of modified methacrylamide monomer (III-19) with the yield of 82%.

(B) Polymerization: by using photo-initiated polymerization, ABVN0.75g, 0.025g (0.1mmol) of modified methacrylamide monomer (III-19) and 2.26g (10mmol) of modified methacrylic acid monomer (IV-19) were added to a reaction tube, polymerization was carried out for 24 hours at room temperature under an inert gas atmosphere, the solid portion obtained by the reaction was dissolved in 20ml of methanol solution, further titrated into 200ml of cold anhydrous ether for precipitation for purification, the insoluble matter was collected by centrifugation at 8000rpm, and the obtained precipitate was placed on a vacuum line and dried overnight under vacuum to obtain 2.5g of surface modifier I-19. The molar ratio of the units III-19 to the units IV-19 in the surface modifier I-19, as determined by 1H-NMR, was 1: 99.

(C) fiber sizing: weighing 0.1g of sizing agent I-19, dissolving in 200ml of acetic acid buffer solution with the pH value of 6, soaking aramid fiber in the solution for 60s, then soaking in deionized water for 10min, and then drying the fiber at 130 ℃ for 1h to obtain modified fiber, wherein the mass fraction of the surface modifier in the modified fiber is 0.01%.

(D) Preparing a composite material: a thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 30% phenolic resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting 40cm by 40cm unidirectional paving layers according to the shape of a die, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 3mm, wherein the volume fraction of the aramid fiber is 70%, the interlaminar shear strength of the composite material is 59.99MPa, and is improved by 98% compared with that of a comparative example 19(30.34 MPa).

The monomers and structural formulas used in examples 1-19 are shown in Table 1.

TABLE 1

The reaction conditions and molar ratios of units III to IV in the products of examples 1 to 19 are shown in Table 2.

Table 2:

comparative example 1

The utility model provides a thermosetting resin base combined material, obtains preimpregnation material with aramid fiber through 25% epoxy resin acetone solution, then dries preimpregnation material and no longer changes until the quality, cuts out the one-way shop layer according to the mould shape, adopts autoclave molding process to prepare this thermosetting resin base aramid fiber combined material, specifically as follows: vacuumizing at room temperature to-0.095 MPa, heating at 0.5 deg.C/min, heating to 80 deg.C, and pressurizing at 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 3mm, wherein the volume fraction of the aramid fiber is 50%, and the interlaminar shear strength of the composite material is 28.85 MPa.

Comparative example 2

A thermosetting resin-based composite material is prepared by the steps of obtaining a prepreg through a 30% epoxy resin acetone solution of fibers obtained in the previous step, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 0.5 deg.C/min, heating to 80 deg.C, and pressurizing at 0.6 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 3mm, wherein the volume fraction of the aramid fiber is 60%, and the interlaminar shear strength of the composite material is 31.37 MPa.

Comparative example 3

A thermosetting resin-based composite material is prepared by the steps of enabling fibers obtained in preparation example B3 to pass through a 30% epoxy resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional ply according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.6 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite plate is 3mm, wherein the volume fraction of the aramid fiber is 60 percent, the interlaminar shear strength of the composite material is 32.54MPa,

comparative example 4

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 35% epoxy resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 100 deg.C, and pressurizing at 0.7 MPa; continuously heating to 200 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 3mm, wherein the volume fraction of the aramid fiber is 70%, and the interlaminar shear strength of the composite material is 34.57 MPa.

Comparative example 5

A thermosetting resin-base composite material is prepared through spreading the reinforcing aramid fibres in a closed mould, injecting 35% solution of epoxy resin in acetone under pressure, immersing said reinforcing aramid fibres in it, solidifying and demoulding. The curing process comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 10mm, wherein the volume fraction of the aramid fiber is 50%, and the interlaminar shear strength of the composite material is 34.28 MPa.

Comparative example 6

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 35% epoxy resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a unidirectional paving layer by 20cm x 20cm according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an oven curing molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 4mm, wherein the volume fraction of the aramid fiber is 80%, and the interlaminar shear strength of the composite material is 35.30 MPa.

Comparative example 7

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 25% polyurethane solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 4mm, wherein the volume fraction of the aramid fiber is 70%, and the interlaminar shear strength of the composite material is 35.97 MPa.

Comparative example 8

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 35% polyurethane acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 4mm, wherein the volume fraction of the aramid fiber is 70%, and the interlaminar shear strength of the composite material is 38.76 MPa.

Comparative example 9

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 25% cyanate ester resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 20 cm-20 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 4mm, wherein the volume fraction of the aramid fiber is 50%, and the interlaminar shear strength of the composite material is 32.17 MPa.

Comparative example 10

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 35% cyanate ester resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a unidirectional 20 cm-20 cm layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 5mm, wherein the volume fraction of the aramid fiber is 70%, and the interlaminar shear strength of the composite material is 36.79 MPa.

Comparative example 11

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 30% polyimide resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a unidirectional 40 cm-40 cm laying layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 5mm, wherein the volume fraction of the aramid fiber is 50%, and the interlaminar shear strength of the composite material is 32.27 MPa.

Comparative example 12

A thermosetting resin-base composite material is prepared through spreading the reinforcing aramid fibres in the mould cavity of closed mould, injecting the 30% solution of polyimide resin in acetone under pressure, immersing said reinforcing aramid fibres in it, solidifying and demoulding. The curing process comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 200mm, wherein the volume fraction of the aramid fiber is 70%, and the interlaminar shear strength of the composite material is 36.12 MPa.

Comparative example 13

The utility model provides a thermosetting resin base aramid fiber composite, obtains the prepreg through 30% bismaleimide resin acetone solution with aramid fiber, then dries the prepreg until the quality no longer changes, cuts 40cm by 40cm one-way layering according to the mould shape, adopts autoclave molding process to prepare this thermosetting resin base aramid fiber composite, specifically as follows: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 0.01mm, wherein the volume fraction of the aramid fiber is 10%, and the interlaminar shear strength of the composite material is 18.28 MPa.

Comparative example 14

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 30% bismaleimide resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 40 cm-by-40 cm unidirectional laying layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting a compression molding process, wherein the specific steps are as follows: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 5mm, wherein the volume fraction of the aramid fiber is 70%, and the interlaminar shear strength of the composite material is 30.20 MPa.

Comparative example 15

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 30% phenolic resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 40 cm-40 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 0.5 deg.C/min, heating to 80 deg.C, and pressurizing at 0.4 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 5mm, wherein the volume fraction of the aramid fiber is 50%, and the interlaminar shear strength of the composite material is 27.37 MPa.

Comparative example 16

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 30% phenolic resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 40 cm-40 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.6 MPa; continuously heating to 180 ℃, preserving the heat for 2h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 5mm, wherein the volume fraction of the aramid fiber is 50%, and the interlaminar shear strength of the composite material is 28.67 MPa.

Comparative example 17

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 30% phenolic resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 40 cm-40 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 1 deg.C/min, heating to 80 deg.C, and pressurizing to 0.6 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 3mm, wherein the volume fraction of the aramid fiber is 60%, and the interlaminar shear strength of the composite material is 29.41 MPa.

Comparative example 18

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 30% phenolic resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 40 cm-40 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 3mm, wherein the volume fraction of the aramid fiber is 60%, and the interlaminar shear strength of the composite material is 30.20 MPa.

Comparative example 19

A thermosetting resin-based composite material is prepared by the steps of enabling aramid fibers to pass through a 30% phenolic resin acetone solution to obtain a prepreg, drying the prepreg until the quality of the prepreg does not change any more, cutting a 40 cm-40 cm unidirectional paving layer according to the shape of a mold, and preparing the thermosetting resin-based aramid composite material by adopting an autoclave molding process, wherein the thermosetting resin-based aramid composite material specifically comprises the following steps: vacuumizing at room temperature to-0.095 MPa, heating at 2 deg.C/min, heating to 80 deg.C, and pressurizing to 0.7 MPa; continuously heating to 180 ℃, preserving heat for 3h, and cooling to below 60 ℃ at the speed of 1 ℃/min. The thickness of the obtained composite material plate is 3mm, wherein the volume fraction of the aramid fiber is 70%, and the interlaminar shear strength of the composite material is 30.34 MPa.

Claims

1. A thermosetting resin-based aramid fiber composite comprising:

(a) the surface of the aramid fiber fabric is coated with a sizing agent, and the aramid fiber fabric is a multi-layer woven bidirectional fabric, a unidirectional fabric, a non-woven fabric or a three-dimensional knitted fabric; and

(b) a cured thermosetting resin;

wherein the cured thermosetting resin (b) is formed from curing an impregnating thermosetting resin system impregnated in the aramid fiber fabric (a); and the impregnated aramid fiber fabric (a) has a thermosetting resin system for impregnation accounting for 10-80 vol% based on the total volume of the impregnated aramid fiber fabric (a).

2. The composite material of claim 1, wherein the surface of the aramid fiber fabric (a) is coated with a sizing agent having the general structural formula:

R₁comprises the following steps: -NH₂、-COOH、-OH、-SH、

Any one of the above;

R₅comprises the following steps: -H, -CH₃

L₁Is any one of-NH-and-O-;

L₂is composed of

3. The composite material of claim 1, wherein the surface of the aramid fiber fabric (a) is coated with a sizing agent in an amount of 0.001 to 3% by mass based on the aramid fiber fabric (a).

4. The composite material of claim 1, wherein R is represented by the general structural formula of the sizing layer₁is-NH₂、

Any one of them.

5. The composite material of claim 1, wherein R is represented by the general structural formula of the sizing layer₂，R₃，R₄Independently of one another, -H, -CH₃、-NH₂and-OH.

6. The composite material of claim 1, wherein the sizing layer has a structural formula L₁is-O-.

7. The composite material as claimed in claim 1, wherein the sizing agent layer has a general structural formula in which L is L, taking into account the influence of the length of the alkylene chain on the solubility and hydrophilicity of the polymer₂Is composed of

Any one of them.

8. The composite of claim 1, wherein the composite has a total thickness of 0.01mm to 200 mm.

9. The composite material of claim 1, wherein the thermosetting resin of the impregnating thermosetting resin system is selected from the group consisting of: phenolic, epoxy, polyurethane, polyimide, bismaleimide or cyanate ester resins.

10. A method of making the composite material of claim 1 having improved impact strength, comprising:

providing an aramid fiber fabric (a) coated with a sizing agent on the surface, wherein the aramid fiber fabric is a woven bidirectional fabric, a unidirectional fabric, a non-woven fabric or a three-dimensional woven fabric;

(ii) impregnating said aramid fiber fabric (a) with an impregnating thermosetting resin system to obtain an impregnated aramid fiber fabric layer; cutting the impregnated aramid fiber fabric layer into a size the same as that of the mold, and laminating 1-50 layers to manufacture a prefabricated product; loading the prefabricated product into a mold, and closing the mold; finally, manufacturing the composite material by using methods of oven curing, autoclave curing, compression molding, resin transfer molding and vacuum auxiliary forming; or

(iii) preparing the aramid fiber fabric (a) into a preformed body, arranging the preformed body in a forming mould, and finally manufacturing the composite material by a resin transfer moulding or vacuum auxiliary forming method.