CN115816925A - Graphene nanosheet-based modified carbon fiber composite material and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of composite material manufacturing, and in particular relates to a graphene nanosheet-based modified carbon fiber composite material and a preparation method thereof. The preparation method of the material comprises the following steps: preparing a polyelectrolyte aqueous solution, adding graphene nanosheets, and ultrasonically dispersing to form a graphene dispersion; pouring the graphene dispersion onto a flat carbon fiber cloth surface to wet the carbon fiber cloth , laying and wetting alternately, until the carbon fiber cloth is laminated to 5-30 layers, and the prefabricated body is obtained after drying and high-temperature heat treatment; the resin glue is prepared, and the resin glue is impregnated with the prefabricated body by a vacuum infusion process. After heating and curing, a modified carbon fiber composite material based on graphene nanosheets was obtained. The preparation method is simple, and uneven dispersion of graphene can be avoided, and the bending strength, bending modulus, interlayer shear strength, thermal conductivity and electrical conductivity of the obtained composite material are significantly improved.

Description

A kind of modified carbon fiber composite material based on graphene nanosheet and its preparation method

technical field

The invention belongs to the technical field of composite material manufacturing, and in particular relates to a graphene nanosheet-based modified carbon fiber composite material and a preparation method thereof.

Background technique

Carbon fiber reinforced resin matrix composites (CFRP) are widely used in aerospace, transportation, equipment manufacturing and many other fields due to their advantages of light weight, high strength, good fatigue resistance, and simple preparation process. Due to the anisotropy of carbon fiber materials, carbon fiber composites have excellent longitudinal mechanical, thermal and electrical properties, but low mechanical properties in the transverse direction. At the same time, because the fiber cloth is bonded by the matrix resin, the transverse thermal and electrical conductivity of the composite material is poor, which limits the application range of carbon fiber composite materials.

With the rapid development of nanotechnology, nanomaterials modified carbon fiber composites have attracted widespread attention. Graphene has unique mechanical, optical, electromagnetic and other properties due to its unique geometric structure, which has aroused people's research interest. Graphene is considered to be the most ideal two-dimensional nano-modified material for polymers. The introduction of graphene into fiber-reinforced resin-based composites can further improve the mechanical, thermal, and electrical properties of composites. The traditional preparation method of nanomaterial-modified carbon fiber composites is generally to first disperse graphene in organic solvent, then add resin glue, and then compound graphene/resin glue mixture and fiber by appropriate method to prepare graphene-modified carbon fiber composite. permanent fiber composites. Traditional preparation methods usually use organic solvents, and graphene is easily filtered by fibers when the infusion process is used, resulting in uneven distribution of graphene and affecting the overall performance of the composite material. Therefore, it is necessary to improve the introduction of graphene in order to introduce graphene into fiber composites through an environmentally friendly method to prepare graphene-modified carbon fiber composites with better performance.

Contents of the invention

The purpose of the present invention is to provide a modified carbon fiber composite material based on graphene nanosheets and its preparation method. The carbon fiber composite material provided by the present invention has excellent bending performance, interlaminar shear performance, thermal conductivity and electrical conductivity, and the present invention The preparation method is green and environmentally friendly, and it is easy to prepare graphene-modified carbon fiber composite materials on a large scale.

In order to achieve the above object, the present invention provides the following technical solutions:

The present invention provides a kind of preparation method based on graphene nano sheet modified carbon fiber composite material, comprises the following steps:

S1. Add the polymer electrolyte to water, heat and stir in a water bath until it is completely dissolved to form an aqueous polyelectrolyte solution;

S2. adding the graphene nanosheets to the polyelectrolyte aqueous solution described in step S1, ultrasonically dispersing, and preparing a graphene dispersion;

S3. pour the graphene dispersion described in step S2 on the flat carbon fiber cloth surface, make carbon fiber cloth moisten, spread a layer of carbon fiber cloth again, pour graphene dispersion liquid and lay carbon fiber cloth and carry out alternately, until the carbon fiber The cloth is layered and laid to 5~30 layers, and the graphene/carbon fiber composite prefabricated body is obtained after drying and high-temperature heat treatment;

S4. Prepare a resin glue, impregnate the resin glue into the graphene/carbon fiber composite prefabricated body described in step S3 by using a vacuum infusion process, heat and solidify, and obtain a modified carbon fiber composite material based on graphene nanosheets.

The role of the polymer electrolyte in the present invention is to disperse graphene.

Preferably, the polymer electrolyte in the step S1 is polyvinyl alcohol, and the weight average molecular weight of polyvinyl alcohol is 25,000-150,000.

Preferably, the heating temperature of the water bath in the step S1 is 85-100° C., the stirring method is magnetic stirring or mechanical stirring, and the stirring speed is 300-1000 rpm.

Preferably, the concentration of the polyelectrolyte aqueous solution in the step S1 is 0.5-2 mg/ml.

Preferably, the graphene nanosheets in the step S2 are single-layer, double-layer or multilayer graphene, the thickness of the graphene nanosheets is 0.3-25 nm, the radial width is 1-40 μm, and the longitudinal thermal conductivity is 1500-3000 W/(m·K), and the specific surface area is 10-300 m ² /g.

Preferably, the power of the ultrasonic dispersion in the step S2 is 80-700 W, and the ultrasonic time is 5-15 min.

Preferably, the concentration of graphene in the graphene dispersion in step S2 is 0.2-4 mg/ml.

Preferably, the drying method in step S3 is supercritical drying, the temperature of high temperature heat treatment is 650-800°C, the time of high temperature heat treatment is 1-3 h, and the atmosphere of high temperature heat treatment is high-purity argon or nitrogen.

Preferably, the carbon fiber cloth in the step S3 is polyacrylonitrile-based carbon fiber, pitch-based carbon fiber or viscose-based carbon fiber.

Preferably, the mass fraction of graphene in the graphene/carbon fiber composite preform in step S3 is 0.1-3.0 wt.%.

After the high-temperature heat treatment in step S3, the polyvinyl alcohol is completely decomposed.

Preferably, the resin glue in the step S4 is a mixed glue of epoxy resin and amine curing agent, and the viscosity of the epoxy resin is 600-2500 mPa·s; the epoxy resin is a low-viscosity double Phenol A type epoxy resin, bisphenol F type epoxy resin or cycloaliphatic epoxy resin.

Further preferably, the mass ratio of the epoxy resin to the amine curing agent in the resin glue is (2-6):1.

Preferably, in the carbon fiber composite material modified based on graphene nanosheets in the step S4, the mass fraction of graphene is 0.05-1.0 wt.%.

The present invention also provides the modified carbon fiber composite material based on graphene nanosheets prepared by the above method.

Compared with the prior art, the preparation method based on graphene nanosheet modified carbon fiber composite material of the present invention has the following outstanding beneficial effects:

(1) In the present invention, graphene nanosheets are directly combined with carbon fiber cloth to form a composite prefabricated body by supercritical drying method, and the whole composite prefabricated body is used as a reinforcing material to prepare a modified carbon fiber composite material based on graphene nanosheets, which solves the problem of graphene nanosheets. It is difficult to disperse the flakes uniformly in the fiber composite material.

(2) The preparation process of the present invention does not use organic solvents, and is environmentally friendly; the preparation method is simple, and the prepared graphene nanosheet/carbon fiber composite prefabricated reinforcement material can adapt to a mature vacuum infusion process and realize large-scale production.

(3) The graphene in the graphene/carbon fiber composite prefabricated body of the present invention is evenly distributed between the layers of the fiber cloth and the fiber gap, which can significantly enhance the comprehensive performance of the fiber composite material; the bending strength and bending modulus of the prepared composite material The amount, interlayer shear strength, thermal conductivity and electrical conductivity are significantly improved.

Description of drawings

Figure 1 is an appearance picture of the graphene/carbon fiber composite preform prepared in Example 3 of the present invention.

Fig. 2 is the SEM picture of the graphene/carbon fiber composite preform prepared in Example 3 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments, and the advantages and characteristics of the present invention will become clearer along with the description. However, the examples are merely exemplary and do not limit the scope of the present invention in any way. Those skilled in the art should understand that the details and forms of the technical solutions of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the protection scope of the present invention.

Example 1

A preparation method based on graphene nanosheet modified carbon fiber composite material, comprising the following steps:

(1) Add 0.2 g of polyvinyl alcohol (Mw=47000) into 200 ml of water, heat and magnetically stir in a water bath at 95 °C at a speed of 500 r/min, until completely dissolved to form a polyvinyl alcohol aqueous solution with a concentration of 1 mg/ml;

(2) 0.1 g of multilayer graphene nanosheets (with an average thickness of 5 nm, an average radial width of 5 μm, a longitudinal thermal conductivity of 3000 W/(m K), and a transverse thermal conductivity of 6 W/( m·K), the specific surface area is 120 m ² /g), was added to 200 ml of polyvinyl alcohol aqueous solution, ultrasonically dispersed at 250 W for 5 min, and prepared into a 0.5 mg/ml graphene dispersion;

(3) Measure 16.6 ml of graphene dispersion and pour it on the surface of a flat piece of polyacrylonitrile-based unidirectional carbon fiber cloth (24K, 200 g/m ² ), wet the carbon fiber cloth, spread another layer of carbon fiber cloth, pour Graphene dispersion and laying carbon fiber cloth were carried out alternately until the carbon fiber cloth was laminated to 12 layers, and after supercritical drying and heat treatment at 700 °C for 2 h, a graphene/carbon fiber composite preform was obtained; the mass fraction of graphene in the composite preform was 0.32 wt.%.

(4) According to the mass ratio of 100: 26.4, the mixed glue solution of cycloaliphatic epoxy resin TDE-85 (room temperature viscosity is 1600-2000mPa s) and m-phenylenediamine is prepared, and the glue solution is impregnated by vacuum infusion process ( The graphene/carbon fiber composite preform in 3) was cured at 80°C and 120°C for 2 h and 4 h, respectively, to obtain a graphene nanosheet-based modified carbon fiber composite material with a graphene nanosheet content of 0.1 wt.%.

Example 2

A preparation method based on graphene nanosheet modified carbon fiber composite material, comprising the following steps:

(1) Add 0.2 g of polyvinyl alcohol (Mw=47000) into 200 ml of water, heat and magnetically stir in a water bath at 95 °C at a speed of 500 r/min, until completely dissolved to form a polyvinyl alcohol aqueous solution with a concentration of 1 mg/ml;

(2) 0.2 g multilayer graphene nanosheets (average thickness 5 nm, average radial width 5 μm, longitudinal thermal conductivity 3000 W/(m K), transverse thermal conductivity 6 W/( m·K), the specific surface area is 120 m ² /g), was added to 200 ml polyvinyl alcohol aqueous solution, and ultrasonically dispersed at 250 W power for 5 min to prepare a 1.0 mg/ml graphene dispersion;

(3) Measure 16.6 ml of graphene dispersion and pour it on the surface of a flat piece of polyacrylonitrile-based unidirectional carbon fiber cloth (24K, 200 g/m ² ), wet the carbon fiber cloth, spread another layer of carbon fiber cloth, pour Graphene dispersion and laying carbon fiber cloth were carried out alternately until the carbon fiber cloth was laminated to 12 layers, and after supercritical drying and heat treatment at 700 °C for 2 h, a graphene/carbon fiber composite preform was obtained; the mass fraction of graphene in the composite preform was 0.64 wt.%.

(4) Prepare a mixed glue solution of cycloaliphatic epoxy resin TDE-85 (room temperature viscosity: 1600-2000mPa s) and m-phenylenediamine according to the mass ratio of 100:26.4, and use the vacuum infusion process to impregnate the glue solution ( The graphene/carbon fiber composite preform in 3) was cured at 80°C and 120°C for 2 h and 4 h, respectively, to obtain a graphene nanosheet-based modified carbon fiber composite material with a graphene nanosheet content of 0.2 wt.%.

Example 3

A preparation method based on graphene nanosheet modified carbon fiber composite material, comprising the following steps:

(1) Add 0.2 g of polyvinyl alcohol (Mw=47000) into 200 ml of water, heat and magnetically stir in a water bath at 95 °C at a speed of 500 r/min, until completely dissolved to form a polyvinyl alcohol aqueous solution with a concentration of 1 mg/ml;

(2) 0.3 g of multilayer graphene nanosheets (with an average thickness of 5 nm, an average radial width of 5 μm, a longitudinal thermal conductivity of 3000 W/(m K), and a transverse thermal conductivity of 6 W/( m·K), the specific surface area is 120 m ² /g), was added to 200 ml polyvinyl alcohol aqueous solution, and ultrasonically dispersed at 250 W power for 5 min to prepare a 1.5 mg/ml graphene dispersion;

(3) Measure 16.6 ml of graphene dispersion and pour it on the surface of a flat piece of polyacrylonitrile-based unidirectional carbon fiber cloth (24K, 200 g/m ² ), wet the carbon fiber cloth, spread another layer of carbon fiber cloth, pour Graphene dispersion and laying carbon fiber cloth were carried out alternately until the carbon fiber cloth was laminated to 12 layers, and after supercritical drying and heat treatment at 700 °C for 2 h, a graphene/carbon fiber composite preform was obtained; the mass fraction of graphene in the composite preform was 0.96 wt.%.

(4) Prepare a mixed glue solution of cycloaliphatic epoxy resin TDE-85 (room temperature viscosity: 1600-2000mPa s) and m-phenylenediamine according to the mass ratio of 100:26.4, and use the vacuum infusion process to impregnate the glue solution ( The graphene/carbon fiber composite preform in 3) was cured at 80°C and 120°C for 2 h and 4 h, respectively, to obtain a graphene nanosheet-based modified carbon fiber composite material with a graphene nanosheet content of 0.3 wt.%.

Example 4

A preparation method based on graphene nanosheet modified carbon fiber composite material, comprising the following steps:

(1) Add 0.2 g of polyvinyl alcohol (Mw=47000) into 200 ml of water, heat and magnetically stir in a water bath at 95 °C at a speed of 500 r/min, until completely dissolved to form a polyvinyl alcohol aqueous solution with a concentration of 1 mg/ml;

(2) 0.4 g multilayer graphene nanosheets (average thickness 5 nm, average radial width 5 μm, longitudinal thermal conductivity 3000 W/(m K), transverse thermal conductivity 6 W/( m·K), the specific surface area is 120 m ² /g), was added to 200 ml polyvinyl alcohol aqueous solution, ultrasonically dispersed at 250 W power for 5 min, and 2 mg/ml graphene dispersion was prepared;

(3) Measure 16.6 ml of graphene dispersion and pour it on the surface of a flat piece of polyacrylonitrile-based unidirectional carbon fiber cloth (24K, 200 g/m ² ), wet the carbon fiber cloth, spread another layer of carbon fiber cloth, pour Graphene dispersion and laying carbon fiber cloth were carried out alternately until the carbon fiber cloth was laminated to 12 layers, and after supercritical drying and heat treatment at 700 °C for 2 h, a graphene/carbon fiber composite preform was obtained; the mass fraction of graphene in the composite preform was 1.28 wt.%.

(4) Prepare a mixed glue solution of cycloaliphatic epoxy resin TDE-85 (room temperature viscosity: 1600-2000mPa s) and m-phenylenediamine according to the mass ratio of 100:26.4, and use the vacuum infusion process to impregnate the glue solution ( The graphene/carbon fiber composite preform in 3) was cured at 80°C and 120°C for 2 h and 4 h, respectively, to obtain a graphene nanosheet-based modified carbon fiber composite material with a graphene nanosheet content of 0.4 wt.%.

Comparative example 1

A method for preparing a carbon fiber composite material, comprising the following steps:

(1) Add 0.2 g of polyvinyl alcohol (Mw=47000) into 200 ml of water, heat and stir in a water bath at 95 °C until completely dissolved, and form an aqueous solution of polyvinyl alcohol with a concentration of 1 mg/ml;

(2) Measure 16.6 ml of polyvinyl alcohol aqueous solution and pour it on the surface of a flat piece of polyacrylonitrile-based unidirectional carbon fiber cloth (24K, 200 g/m ² ) to wet the carbon fiber cloth, then spread a layer of carbon fiber cloth, pour The polyvinyl alcohol aqueous solution and the laying of carbon fiber cloth are carried out alternately until the carbon fiber cloth is laminated to 12 layers, and the carbon fiber composite prefabricated body is obtained after supercritical drying and heat treatment at 700 °C for 2 h;

(3) Prepare a mixed glue solution of cycloaliphatic epoxy resin TDE-85 and m-phenylenediamine according to the mass ratio of 100:26.4, and use the vacuum infusion process to impregnate the carbon fiber composite prefabricated body in step (3) with the glue solution. Curing at 80 ℃ and 120 ℃ for 2 h and 4 h, respectively, to obtain unmodified carbon fiber composites; wherein, the volume fraction of carbon fibers in the carbon fiber composites was 72 vol.%.

Comparative example 2

A method for preparing a carbon fiber composite material. Compared with Example 1, the difference is that the graphene mass fraction in the graphene/carbon fiber composite preform in step (3) is 3.8 wt.%; and, the final obtained based on The mass fraction of graphene in the graphene nanosheet modified carbon fiber composite was 1.2 wt.%.

Performance Characterization and Results

For the samples obtained in Examples 1-4 and Comparative Examples 1-2, the bending performance test was carried out according to ASTM D790, the interlaminar shear strength test was carried out according to ASTM D2344, the thermal conductivity test was carried out according to the ASTM-E1461 standard, and the ASTM D257 standard was carried out. The volume resistivity test, the test results are shown in Table 1.

Table 1. The performance test results of the modified carbon fiber composite material based on graphene nanosheets obtained in the examples and comparative examples

Visible embodiment 1～4 of the present invention compares with comparative example 1, and along with the increase of graphene nano sheet content, the flexural strength of composite material, flexural modulus, ply of prepared graphene/carbon fiber/epoxy resin composite material The inter-shear strength and thermal conductivity are significantly improved, and the volume resistivity is decreased. This is due to the graphene/carbon fiber composite preform can be completely infiltrated by the resin within the appropriate graphene content range, and the dispersion of graphene in the carbon fiber composite material is better (see accompanying drawings 1 and 2 of the description), An effective thermal and conductive network is formed between the layers of the composite material, which fully exerts the modification effect of graphene and improves the mechanical, thermal and electrical properties of the composite material.

Comparative Example 2 shows that: when the content of graphene in the carbon fiber composite exceeds 1.0 wt.%, the mechanical properties of the composite such as flexural strength, flexural modulus and interlaminar shear strength are all lower than those of Examples 1 to 4, Moreover, the thermal conductivity is lower than that of Example 3 and Example 4, and the volume resistivity is higher than that of Example 3 and Example 4. This is because when the graphene content in the carbon fiber composite material is too high, the distribution of graphene is uneven, and the graphene/carbon fiber composite prefabricated body is denser, which leads to the inability to be fully impregnated by the glue solution, resulting in more defects in the composite material.

The technology of the present invention combines an appropriate amount of graphene nanosheets directly with carbon fiber cloth to form a composite prefabricated body through a supercritical drying method, and can prepare high-performance graphene nanosheet-based modified carbon fiber composite materials in batches through a vacuum infusion process, and prepare The process is green and environmentally friendly.

Claims (10)

1. A preparation method of a graphene nanosheet-based modified carbon fiber composite material is characterized by comprising the following steps:

s1, adding polymer electrolyte into water, heating in a water bath and stirring until the polymer electrolyte is completely dissolved to form a polyelectrolyte aqueous solution;

s2, adding graphene nanosheets into the polyelectrolyte aqueous solution obtained in the step S1, and performing ultrasonic dispersion to prepare a graphene dispersion solution;

s3, pouring the graphene dispersion liquid on the surface of the flat carbon fiber cloth in the step S2 to wet the carbon fiber cloth, laying a layer of carbon fiber cloth, alternately pouring the graphene dispersion liquid and laying the carbon fiber cloth until the carbon fiber cloth is laminated and laid for 5-30 layers, and drying and carrying out high-temperature heat treatment to obtain a graphene/carbon fiber composite prefabricated body;

s4, preparing a resin glue solution, impregnating the graphene/carbon fiber composite prefabricated body in the step S3 with the resin glue solution by adopting a vacuum infusion process, and heating and curing to obtain the graphene nanosheet modified carbon fiber composite material.

2. The method according to claim 1, wherein the polymer electrolyte in step S1 is polyvinyl alcohol having a weight average molecular weight of 2.5 to 15 ten thousand; preferably, the water bath heating temperature in the step S1 is 85-100 ℃, the stirring mode is magnetic stirring or mechanical stirring, and the stirring speed is 300-1000 rpm.

3. The method according to claim 1, wherein the concentration of the aqueous polyelectrolyte solution in step S1 is 0.5 to 2 mg/ml.

4. The preparation method according to claim 1, wherein the graphene nanoplatelets in step S2 are single-layer, double-layer or multi-layer graphene, the graphene nanoplatelets have a thickness of 0.3 to 25 nm, a radial width of 1 to 40 μm, a longitudinal thermal conductivity of 1500 to 3000W/(m-K), and a specific surface area of 10 to 300 m ² (ii)/g; preferably, the power of ultrasonic dispersion in step S2 is 80-700W, and the ultrasonic time is 5-15 min.

5. The method according to claim 1, wherein the concentration of graphene in the graphene dispersion liquid in step S2 is 0.2 to 4 mg/ml.

6. The preparation method according to claim 1, wherein the drying manner in step S3 is supercritical drying, the temperature of the high-temperature heat treatment is 650 to 800 ℃, the time of the high-temperature heat treatment is 1 to 3 hours, and the atmosphere of the high-temperature heat treatment is high-purity argon or nitrogen; preferably, the carbon fiber cloth in the step S3 is polyacrylonitrile-based carbon fiber, pitch-based carbon fiber or viscose-based carbon fiber; preferably, the mass fraction of graphene in the graphene/carbon fiber composite preform in the step S3 is 0.1 to 3.0 wt.%.

7. The preparation method according to claim 1, wherein the resin glue solution in the step S4 is a mixed glue solution of epoxy resin and amine curing agent, and the viscosity of the epoxy resin is 600 to 2500 mPa-S; the epoxy resin is low-viscosity bisphenol A epoxy resin, bisphenol F epoxy resin or alicyclic epoxy resin.

8. The preparation method according to claim 7, wherein the mass ratio of the epoxy resin to the amine curing agent in the resin glue solution is (2-6): 1.

9. The preparation method according to claim 1, wherein the mass fraction of graphene in the graphene nanoplatelet-based modified carbon fiber composite material of step S4 is 0.05 to 1.0 wt.%.

10. Graphene nanoplatelet-based modified carbon fiber composite prepared according to the preparation method of any one of claims 1 to 9.

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