CN102787488A - Method for preparing graphene oxide grafting surface modification carbon fiber - Google Patents

Abstract

A method for preparing a graphene oxide grafting surface modification carbon fiber relates to a carbon fiber modification method, and is used for solving the technical problems that the existing carbon fiber has low surface activity, reduced surface tension and poor wettability with a resin matrix, and the interlaminar shear strength of a composite material is caused to reduce. The method comprises the steps as follows: 1, graphite oxidization; 2, separation of graphite oxide mother liquor; 3, functionalization of graphite oxide; 4, carbon fiber surface functionalization; and 5, carbon fiber surface graphite oxide treatment. The graphite oxide uniformly covers the carbon fiber surface, the roughness of the carbon fiber surface can be greatly improved, and accordingly, the interfacial properties of a carbon fiber reinforced composite material can be improved by an anchoring action. The interfacial shear strength of the surface grafting graphene oxide carbon fiber/carbon composite material which is prepared through graphene oxide grafting modification can be improved by 25% in comparison with that of the untreated surface grafting graphene oxide carbon fiber/carbon composite material.

Description

Method for Grafting Graphene Oxide Surface Modified Carbon Fiber

technical field

The invention relates to a modification method of carbon fiber.

Background technique

Carbon fiber, as the name suggests, not only has the inherent characteristics of carbon materials, but also has the softness and processability of textile fibers. It is a new generation of reinforcing fibers. Carbon fiber is a microcrystalline graphite material obtained by carbonizing and graphitizing organic fibers. The microstructure of carbon fiber is similar to artificial graphite, which is a turbostratic graphite structure. Carbon fiber is a new material with excellent mechanical properties. Its specific gravity is less than 1/4 of that of steel. The tensile strength of carbon fiber resin composite materials is generally above 3500Mpa, which is 7-9 times that of steel. The tensile modulus of elasticity is 230 ~430Gpa is also higher than steel. Therefore, the specific strength of CFRP, that is, the ratio of the strength of the material to its density, can reach more than 2000MPa/(g/cm ³ ), while the specific strength of A3 steel is only about 59Mpa/(g/cm ³ ), and its specific modulus is also higher than that of steel. high. The higher the specific strength of the material, the smaller the self-weight of the component, and the higher the specific modulus, the greater the stiffness of the component. It is because of its excellent performance that it has been widely used in many high-tech products such as aviation, aerospace, automobiles, and sports.

However, since carbon fiber is a new type of carbon material with a carbon content of more than 93% obtained through high-temperature carbonization at 1300°C to 1600°C, it is carbonized in high-temperature inert gas, along with the escape of non-carbon elements and the enrichment of carbon. The surface activity decreases, the surface tension decreases, and the wettability with the resin matrix becomes poor. In addition, in order to increase the tensile strength of carbon fibers, surface defects need to be minimized, so their surface area is also small. The anchoring effect between such a smooth surface and the matrix resin is also poor, resulting in a decrease in the interlaminar shear strength of the composite material, which cannot meet the design requirements for use. Therefore, when carbon fiber is used as a reinforcing material to prepare composite materials, the carbon fiber must first undergo surface modification treatment to improve the interfacial bonding between it and the matrix material.

Contents of the invention

The present invention provides a graphene oxide grafted surface-modified carbon fiber in order to solve the technical problems of low surface activity of the existing carbon fiber, decreased surface tension, poor wettability with the resin matrix, and reduced interlayer shear strength of the composite material. Methods.

The method of graphene oxide grafting surface modified carbon fiber is carried out as follows:

1. Graphite oxidation:

Add graphite into the mixture of strong oxidizing acid and nitrate, cool to -5°C~0°C, stir and add potassium-containing strong oxidant at a speed of 50rpm~200rpm, and continue stirring for 4h~12h to obtain a mixed solution. Pour the solution into a water bath at 10°C to 50°C, continue to react for 40min to 60min, then add hot water at 90°C to 100°C, make the system boil and keep it for 20min to 40min, then add hydrogen peroxide solution with a volume concentration of 40% to 60%. , stirred at a speed of 100rpm to 500rpm until completely dissolved, then washed with ultrapure water for 3 to 6 times, filtered until there was no SO ₄ ^2- in the filter cake, and then freeze-dried at -35°C to obtain graphite oxide;

Wherein the mass ratio of graphite and strong oxidizing acid is 1: (0.025～5); the mass ratio of graphite and nitrate is 1: (0.2～8); the mass ratio of graphite and potassium-containing strong oxidant is 1: (0.1～4 ); the mass ratio of graphite to hydrogen peroxide is 1: (0.125～4);

2. Stripping of graphite oxide mother liquor:

Dissolve graphite oxide in a solvent, and ultrasonically vibrate for 0.5h-12h under the condition of ultrasonic power of 100W-1000W, then centrifuge under the condition of centrifuge rotation speed of 3000rpm-10000rpm, and freeze-dry at -35°C to obtain Graphene oxide powder;

3. Graphene oxide functionalization: Add 200ml THF solution, 8gNaBH ₄ and 0.1g I ₂ into the flask, stir to dissolve, then add 0.5g graphene oxide powder to react for 2h, and freeze-dry for 24h to obtain carboxyl graphene oxide;

Weigh 0.0025g of carboxyl graphene oxide and 15ml of distilled water into a beaker, then add 5ml of silane coupling agent KH-550, react in a constant temperature water bath at 75°C for 6h, then centrifuge at 12000 rpm for 10min, pour off the supernatant Then add tetrahydrofuran and centrifuge at a speed of 12000 rpm for 10 min, pour off the supernatant, collect the aminated graphene oxide viscous liquid and freeze-dry to obtain aminated graphene oxide;

4. Surface functionalization of carbon fiber:

Wind the carbon fiber on the square glass frame, then immerse the square glass frame into a beaker filled with mixed acid, the mixed acid is composed of concentrated nitric acid and concentrated sulfuric acid, wherein the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 3:1, and then the beaker Place on a magnetic stirrer, react at room temperature for 8 hours, wash with deionized water until the washing solution is neutral, and then vacuum dry at 100°C for 24 hours to obtain acid-oxidized carbon fibers;

Fix the acid-oxidized carbon fiber with glass fiber, then add the acid-oxidized carbon fiber fixed with glass fiber, 160ml of thionyl chloride and 20ml of dimethylformamide into the three-necked flask, and react the three-necked flask at 70°C in a water bath After 48 hours, wash with acetone until the washing solution is neutral, and dry in vacuum at 70°C for 24 hours to obtain carbonyl chloride fibers;

5. Graphene oxide treatment on carbon fiber surface:

Aminated graphene oxide is dissolved in dimethylformamide and then poured into a three-necked flask, and the carbonyl chloride fiber obtained in step 4 is added, wherein the molar ratio of the aminated graphene oxide to carbonyl chloride fiber is 1: 1. Heated in a constant temperature water bath at 70°C for 48 hours, washed with acetone until the filtrate was neutral, and grafted carbon fibers were obtained. The grafted carbon fibers were refluxed with 150ml of acetone for 24 hours, and then vacuum-dried at 60°C for 24 hours to obtain carbon fibers with graphene oxide grafted on the surface.

The invention overcomes the disadvantages of complex equipment and high cost in the prior art, and adopts a method of chemical grafting to realize uniform and firm coverage of graphene oxide on the surface of carbon fibers. This method is simple, easy, and cheap, and is suitable for mass production. Through the uniform coverage of graphene oxide on the surface of carbon fibers, the roughness of the surface of carbon fibers can be greatly improved, thereby improving the interfacial properties of carbon fiber reinforced composites through anchoring. The interfacial shear strength of carbon fiber/carbon composites prepared by grafting graphene oxide on the surface prepared by grafting graphene oxide can be increased by 25% compared with the untreated one.

Description of drawings

Fig. 1 is the SEM surface topography figure of the carbon fiber of the surface graft graphene oxide that experiment one prepares;

Fig. 2 is the SEM surface topography figure of the carbon fiber of the surface graft graphene oxide that experiment two prepares;

Fig. 3 is the SEM surface topography figure of the carbon fiber of the surface graft graphene oxide that experiment three prepares;

Fig. 4 is the SEM surface morphology enlargement figure of the carbon fiber of the surface graft graphene oxide that experiment three prepares;

Fig. 5 is the SEM surface topography diagram of the carbon fiber grafted on the surface of graphene oxide prepared in Experiment 4.

Detailed ways

The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

Specific embodiment one: the method for grafting surface modified carbon fiber of graphene oxide in this embodiment is carried out according to the following steps:

1. Graphite oxidation:

Add graphite into the mixture of strong oxidizing acid and nitrate, cool to -5°C~0°C, stir and add potassium-containing strong oxidant at a speed of 50rpm~200rpm, and continue stirring for 4h~12h to obtain a mixed solution. Pour the solution into a water bath at 10°C to 50°C, continue to react for 40min to 60min, then add hot water at 90°C to 100°C, make the system boil and keep it for 20min to 40min, then add hydrogen peroxide solution with a volume concentration of 40% to 60%. , stirred at a speed of 100rpm to 500rpm until completely dissolved, then washed with ultrapure water for 3 to 6 times, filtered until there was no SO ₄ ^2- in the filter cake, and then freeze-dried at -35°C to obtain graphite oxide;

Wherein the mass ratio of graphite and strong oxidizing acid is 1: (0.025～5); the mass ratio of graphite and nitrate is 1: (0.2～8); the mass ratio of graphite and potassium-containing strong oxidant is 1: (0.1～4 ); the mass ratio of graphite to hydrogen peroxide is 1: (0.125～4);

2. Stripping of graphite oxide mother liquor:

Dissolve graphite oxide in a solvent, and ultrasonically vibrate for 0.5h-12h under the condition of ultrasonic power of 100W-1000W, then centrifuge under the condition of centrifuge rotation speed of 3000rpm-10000rpm, and freeze-dry at -35°C to obtain Graphene oxide powder;

3. Graphene oxide functionalization: Add 200ml THF solution, 8gNaBH ₄ and 0.1g I ₂ into the flask, stir to dissolve, then add 0.5g graphene oxide powder to react for 2h, and freeze-dry for 24h to obtain carboxyl graphene oxide;

Weigh 0.0025g of carboxyl graphene oxide and 15ml of distilled water into a beaker, then add 5ml of silane coupling agent KH-550, react in a constant temperature water bath at 75°C for 6h, then centrifuge at 12000 rpm for 10min, pour off the supernatant Then add tetrahydrofuran and centrifuge at a speed of 12000 rpm for 10 min, pour off the supernatant, collect the aminated graphene oxide viscous liquid and freeze-dry to obtain aminated graphene oxide;

4. Surface functionalization of carbon fiber:

Wind the carbon fiber on the square glass frame, then immerse the square glass frame into a beaker filled with mixed acid, the mixed acid is composed of concentrated nitric acid and concentrated sulfuric acid, wherein the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 3:1, and then the beaker Place on a magnetic stirrer, react at room temperature for 8 hours, wash with deionized water until the lotion is neutral, and then vacuum dry at 100°C for 24 hours to obtain acid-oxidized carbon fibers (this step is mainly to produce reactive carbon fibers on the surface of inert carbon fibers. active functional groups, mainly carboxyl and hydroxyl);

Fix the acid-oxidized carbon fiber with glass fiber filaments (the purpose is to prevent the carbon fibers from being intertwined and difficult to handle during the reaction), and then add the acid-oxidized carbon fiber fixed with glass fiber filaments, 160ml of thionyl chloride and 20ml of dimethylformamide into the three ports In the flask, the three-necked flask was reacted in a water bath at 70°C for 48 hours, washed with acetone until the washing liquid was neutral, and dried in vacuum at 70°C for 24 hours to obtain carbonyl chloride fibers;

5. Graphene oxide treatment on carbon fiber surface:

Aminated graphene oxide is dissolved in dimethylformamide and then poured into a three-necked flask, and the carbonyl chloride fiber obtained in step 4 is added, wherein the molar ratio of the aminated graphene oxide to carbonyl chloride fiber is 1: 1. Heated in a constant temperature water bath at 70°C for 48 hours, washed with acetone until the filtrate was neutral, and grafted carbon fibers were obtained. The grafted carbon fibers were refluxed with 150ml of acetone for 24 hours, and then vacuum-dried at 60°C for 24 hours to obtain carbon fibers with graphene oxide grafted on the surface.

Embodiment 2: This embodiment differs from Embodiment 1 in that the strong oxidizing acid described in step 1 is concentrated sulfuric acid or perchloric acid. Others are the same as in the first embodiment.

Specific embodiment three: the difference between this embodiment and specific embodiment one or two is that the potassium-containing strong oxidizing agent described in step one is potassium permanganate or potassium perchlorate. Others are the same as in the first or second embodiment.

Embodiment 4: The difference between this embodiment and one of Embodiments 1 to 3 is that the nitrate in step 1 is potassium nitrate, sodium nitrate, magnesium nitrate or calcium nitrate. Others are the same as those in the first to third specific embodiments.

Specific embodiment five: the difference between this embodiment and one of specific embodiments one to four is that the solvent described in step 2 is water, ethanol, acetone, ether, chloroform, benzene, toluene, ethylene glycol, tetrahydrofuran, N, N -Dimethylformamide, petroleum ether, methyl acetate, ethyl acetate, carbon tetrachloride, organic chlorides, pyridine, ethylenediamine or carbon disulfide. Others are the same as one of the specific embodiments 1 to 4.

Embodiment 6: This embodiment is different from one of Embodiments 1 to 5 in that it is cooled to -3°C in step 1. Others are the same as one of the specific embodiments 1 to 5.

Specific embodiment seven: the difference between this embodiment and one of specific embodiments one to six is that the mass ratio of graphite and strong oxidizing acid in step 1 is 1: 3; the mass ratio of graphite and nitrate is 1: 2; The mass ratio of potassium strong oxidant is 1:2; the mass ratio of graphite and hydrogen peroxide is 1:2. Others are the same as one of the specific embodiments 1 to 6.

Embodiment 8: The difference between this embodiment and one of Embodiments 1 to 7 is that a hydrogen peroxide solution with a volume concentration of 50% is added in step 1. Others are the same as one of the specific embodiments 1 to 7.

Embodiment 9: The difference between this embodiment and Embodiment 1 to Embodiment 8 is that in step 2, ultrasonic vibration is performed under the condition of ultrasonic power of 500W. Others are the same as one of the specific embodiments 1 to 8.

Embodiment 10: The difference between this embodiment and Embodiment 1 to Embodiment 9 is that in step 2, the centrifuge is centrifuged at a speed of 5000 rpm. Others are the same as one of the specific embodiments 1 to 9.

Adopt following experiment verification effect of the present invention:

experiment one:

The method of graphene oxide grafting surface modified carbon fiber is carried out as follows:

1. Graphite oxidation:

Add graphite to the mixture of perchloric acid and potassium nitrate, cool to -5°C, stir and add potassium perchlorate at a speed of 50rpm, and continue stirring for 4h to obtain a mixed solution, which is poured into a water bath at 10°C, Continue to react for 40 minutes, then add hot water at 95°C, boil the system and keep it for 30 minutes, then add hydrogen peroxide solution with a volume concentration of 50%, stir at a speed of 150 rpm until completely dissolved, then wash with ultrapure water for 5 times, and filter to There is no SO ₄ ^2- in the filter cake, and then freeze-dried at -35°C to obtain graphite oxide;

The mass ratio of graphite to strong oxidizing acid is 1:0.1; the mass ratio of graphite to nitrate is 1:0.2; the mass ratio of graphite to potassium-containing strong oxidant is 1:0.1; the mass ratio of graphite to hydrogen peroxide is 1:0.125 ;

2. Stripping of graphite oxide mother liquor:

Dissolve graphite oxide in a solvent, and ultrasonically vibrate for 3 hours under the condition of ultrasonic power of 200W, then centrifuge under the condition of centrifuge rotation speed of 5000rpm, and freeze-dry at -35°C to obtain graphene oxide powder;

3. Graphene oxide functionalization: Add 200ml THF solution, 8g NaBH ₄ and 0.1g I ₂ into the flask, stir to dissolve, then add 0.5g graphene oxide powder to react for 2 hours, and freeze-dry for 24 hours to obtain carboxyl graphene oxide;

Weigh 0.0025g of carboxyl graphene oxide and 15ml of distilled water into a beaker, then add 5ml of silane coupling agent KH-550, react in a constant temperature water bath at 75°C for 6h, then centrifuge at 12000 rpm for 10min, pour off the supernatant Then add tetrahydrofuran and centrifuge at a speed of 12000 rpm for 10 min, pour off the supernatant, collect the aminated graphene oxide viscous liquid and freeze-dry to obtain aminated graphene oxide;

4. Surface functionalization of carbon fiber:

Wind the carbon fiber on the square glass frame, then immerse the square glass frame into a beaker filled with mixed acid, the mixed acid is composed of concentrated nitric acid and concentrated sulfuric acid, wherein the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 3:1, and then the beaker Place on a magnetic stirrer, react at room temperature for 8 hours, wash with deionized water until the washing solution is neutral, and then vacuum dry at 100°C for 24 hours to obtain acid-oxidized carbon fibers;

Fix the acid-oxidized carbon fiber with glass fiber, then add the acid-oxidized carbon fiber fixed with glass fiber, 160ml of thionyl chloride and 20ml of dimethylformamide into the three-necked flask, and react the three-necked flask at 70°C in a water bath After 48 hours, wash with acetone until the washing solution is neutral, and dry in vacuum at 70°C for 24 hours to obtain carbonyl chloride fibers;

5. Graphene oxide treatment on carbon fiber surface:

Aminated graphene oxide is dissolved in dimethylformamide and then poured into a three-necked flask, and the carbonyl chloride fiber obtained in step 4 is added, wherein the molar ratio of the aminated graphene oxide to carbonyl chloride fiber is 1: 1. Heated in a constant temperature water bath at 70°C for 48 hours, washed with acetone until the filtrate was neutral, and grafted carbon fibers were obtained. The grafted carbon fibers were refluxed with 150ml of acetone for 24 hours, and then vacuum-dried at 60°C for 24 hours to obtain carbon fibers with graphene oxide grafted on the surface.

The interfacial shear strength of the carbon fiber/carbon composite material with surface grafted graphene oxide prepared after graphene oxide graft modification in this experiment was 23% higher than that without treatment.

Experiment 2:

The method of graphene oxide grafting surface modified carbon fiber is carried out as follows:

1. Graphite oxidation:

Add graphite to the mixture of perchloric acid and potassium nitrate, cool to -5°C, stir and add potassium perchlorate at a speed of 50rpm, and continue stirring for 4h to obtain a mixed solution, which is poured into a water bath at 10°C, Continue to react for 40 minutes, then add hot water at 95°C, boil the system and keep it for 30 minutes, then add hydrogen peroxide solution with a volume concentration of 50%, stir at a speed of 150 rpm until completely dissolved, then wash with ultrapure water for 5 times, and filter to There is no SO ₄ ^2- in the filter cake, and then freeze-dried at -35°C to obtain graphite oxide;

The mass ratio of graphite to strong oxidizing acid is 1:0.048; the mass ratio of graphite to nitrate is 1:0.2; the mass ratio of graphite to potassium-containing strong oxidant is 1:0.1; the mass ratio of graphite to hydrogen peroxide is 1:0.125 ;

2. Stripping of graphite oxide mother liquor:

Dissolve graphite oxide in a solvent, and ultrasonically vibrate for 3 hours under the condition of ultrasonic power of 200W, then centrifuge under the condition of centrifuge rotation speed of 5000rpm, and freeze-dry at -35°C to obtain graphene oxide powder;

3. Graphene oxide functionalization: Add 200ml THF solution, 8g NaBH ₄ and 0.1g I ₂ into the flask, stir to dissolve, then add 0.5g graphene oxide powder to react for 2 hours, and freeze-dry for 24 hours to obtain carboxyl graphene oxide;

Weigh 0.0025g of carboxyl graphene oxide and 15ml of distilled water into a beaker, then add 5ml of silane coupling agent KH-550, react in a constant temperature water bath at 75°C for 6h, then centrifuge at 12000 rpm for 10min, pour off the supernatant Then add tetrahydrofuran and centrifuge at a speed of 12000 rpm for 10 min, pour off the supernatant, collect the aminated graphene oxide viscous liquid and freeze-dry to obtain aminated graphene oxide;

4. Surface functionalization of carbon fiber:

Wind the carbon fiber on the square glass frame, then immerse the square glass frame into a beaker filled with mixed acid, the mixed acid is composed of concentrated nitric acid and concentrated sulfuric acid, wherein the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 3:1, and then the beaker Place on a magnetic stirrer, react at room temperature for 8 hours, wash with deionized water until the washing solution is neutral, and then vacuum dry at 100°C for 24 hours to obtain acid-oxidized carbon fibers;

Fix the acid-oxidized carbon fiber with glass fiber, then add the acid-oxidized carbon fiber fixed with glass fiber, 160ml of thionyl chloride and 20ml of dimethylformamide into the three-necked flask, and react the three-necked flask at 70°C in a water bath After 48 hours, wash with acetone until the washing solution is neutral, and dry in vacuum at 70°C for 24 hours to obtain carbonyl chloride fibers;

5. Graphene oxide treatment on carbon fiber surface:

Aminated graphene oxide is dissolved in dimethylformamide and then poured into a three-necked flask, and the carbonyl chloride fiber obtained in step 4 is added, wherein the molar ratio of the aminated graphene oxide to carbonyl chloride fiber is 1: 1. Heated in a constant temperature water bath at 70°C for 48 hours, washed with acetone until the filtrate was neutral, and grafted carbon fibers were obtained. The grafted carbon fibers were refluxed with 150ml of acetone for 24 hours, and then vacuum-dried at 60°C for 24 hours to obtain carbon fibers with graphene oxide grafted on the surface.

The interfacial shear strength of the carbon fiber/carbon composite material with surface grafted graphene oxide prepared after graphene oxide graft modification in this experiment can be increased by 24% compared with that without treatment.

Experiment three:

The method of graphene oxide grafting surface modified carbon fiber is carried out as follows:

1. Graphite oxidation:

Add graphite to the mixture of perchloric acid and potassium nitrate, cool to -5°C, stir and add potassium perchlorate at a speed of 50rpm, and continue stirring for 4h to obtain a mixed solution, which is poured into a water bath at 10°C, Continue to react for 40 minutes, then add hot water at 95°C, boil the system and keep it for 30 minutes, then add hydrogen peroxide solution with a volume concentration of 50%, stir at a speed of 150 rpm until completely dissolved, then wash with ultrapure water for 5 times, and filter to There is no SO ₄ ^2- in the filter cake, and then freeze-dried at -35°C to obtain graphite oxide;

The mass ratio of graphite to strong oxidizing acid is 1:0.025; the mass ratio of graphite to nitrate is 1:0.2; the mass ratio of graphite to potassium-containing strong oxidant is 1:0.1; the mass ratio of graphite to hydrogen peroxide is 1:0.125 ;

2. Stripping of graphite oxide mother liquor:

Dissolve graphite oxide in a solvent, and ultrasonically vibrate for 3 hours under the condition of ultrasonic power of 200W, then centrifuge under the condition of centrifuge rotation speed of 5000rpm, and freeze-dry at -35°C to obtain graphene oxide powder;

3. Graphene oxide functionalization: Add 200ml THF solution, 8g NaBH ₄ and 0.1g I ₂ into the flask, stir to dissolve, then add 0.5g graphene oxide powder to react for 2 hours, and freeze-dry for 24 hours to obtain carboxyl graphene oxide;

Weigh 0.0025g of carboxyl graphene oxide and 15ml of distilled water into a beaker, then add 5ml of silane coupling agent KH-550, react in a constant temperature water bath at 75°C for 6h, then centrifuge at 12000 rpm for 10min, pour off the supernatant Then add tetrahydrofuran and centrifuge at a speed of 12000 rpm for 10 min, pour off the supernatant, collect the aminated graphene oxide viscous liquid and freeze-dry to obtain aminated graphene oxide;

4. Surface functionalization of carbon fiber:

Wind the carbon fiber on the square glass frame, then immerse the square glass frame into a beaker filled with mixed acid, the mixed acid is composed of concentrated nitric acid and concentrated sulfuric acid, wherein the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 3:1, and then the beaker Place on a magnetic stirrer, react at room temperature for 8 hours, wash with deionized water until the washing solution is neutral, and then vacuum dry at 100°C for 24 hours to obtain acid-oxidized carbon fibers;

Fix the acid-oxidized carbon fiber with glass fiber, then add the acid-oxidized carbon fiber fixed with glass fiber, 160ml of thionyl chloride and 20ml of dimethylformamide into the three-necked flask, and react the three-necked flask at 70°C in a water bath After 48 hours, wash with acetone until the washing solution is neutral, and dry in vacuum at 70°C for 24 hours to obtain carbonyl chloride fibers;

5. Graphene oxide treatment on carbon fiber surface:

Aminated graphene oxide is dissolved in dimethylformamide and then poured into a three-necked flask, and the carbonyl chloride fiber obtained in step 4 is added, wherein the molar ratio of the aminated graphene oxide to carbonyl chloride fiber is 1: 1. Heated in a constant temperature water bath at 70°C for 48 hours, washed with acetone until the filtrate was neutral, and grafted carbon fibers were obtained. The grafted carbon fibers were refluxed with 150ml of acetone for 24 hours, and then vacuum-dried at 60°C for 24 hours to obtain carbon fibers with graphene oxide grafted on the surface.

The interfacial shear strength of the carbon fiber/carbon composite material with surface grafted graphene oxide prepared after graphene oxide graft modification in this experiment was 25% higher than that of the untreated one.

Experiment 4:

The method of graphene oxide grafting surface modified carbon fiber is carried out as follows:

1. Graphite oxidation:

Add graphite to the mixture of perchloric acid and potassium nitrate, cool to -5°C, stir and add potassium perchlorate at a speed of 50rpm, and continue stirring for 4h to obtain a mixed solution, which is poured into a water bath at 10°C, Continue to react for 40 minutes, then add hot water at 95°C, boil the system and keep it for 30 minutes, then add hydrogen peroxide solution with a volume concentration of 50%, stir at a speed of 150 rpm until completely dissolved, then wash with ultrapure water for 5 times, and filter to There is no SO ₄ ^2- in the filter cake, and then freeze-dried at -35°C to obtain graphite oxide;

The mass ratio of graphite to strong oxidizing acid is 1:0.0125; the mass ratio of graphite to nitrate is 1:0.2; the mass ratio of graphite to potassium-containing strong oxidant is 1:0.1; the mass ratio of graphite to hydrogen peroxide is 1:0.125 ;

2. Stripping of graphite oxide mother liquor:

Dissolve graphite oxide in a solvent, and ultrasonically vibrate for 3 hours under the condition of ultrasonic power of 200W, then centrifuge under the condition of centrifuge rotation speed of 5000rpm, and freeze-dry at -35°C to obtain graphene oxide powder;

3. Graphene oxide functionalization: Add 200ml THF solution, 8g NaBH ₄ and 0.1g I ₂ into the flask, stir to dissolve, then add 0.5g graphene oxide powder to react for 2 hours, and freeze-dry for 24 hours to obtain carboxyl graphene oxide;

Weigh 0.0025g of carboxyl graphene oxide and 15ml of distilled water into a beaker, then add 5ml of silane coupling agent KH-550, react in a constant temperature water bath at 75°C for 6h, then centrifuge at 12000 rpm for 10min, pour off the supernatant Then add tetrahydrofuran and centrifuge at a speed of 12000 rpm for 10 min, pour off the supernatant, collect the aminated graphene oxide viscous liquid and freeze-dry to obtain aminated graphene oxide;

4. Surface functionalization of carbon fiber:

Wind the carbon fiber on the square glass frame, then immerse the square glass frame into a beaker filled with mixed acid, the mixed acid is composed of concentrated nitric acid and concentrated sulfuric acid, wherein the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 3:1, and then the beaker Place on a magnetic stirrer, react at room temperature for 8 hours, wash with deionized water until the washing solution is neutral, and then vacuum dry at 100°C for 24 hours to obtain acid-oxidized carbon fibers;

Fix the acid-oxidized carbon fiber with glass fiber, then add the acid-oxidized carbon fiber fixed with glass fiber, 160ml of thionyl chloride and 20ml of dimethylformamide into the three-necked flask, and react the three-necked flask at 70°C in a water bath After 48 hours, wash with acetone until the washing solution is neutral, and dry in vacuum at 70°C for 24 hours to obtain carbonyl chloride fibers;

5. Graphene oxide treatment on carbon fiber surface:

Aminated graphene oxide is dissolved in dimethylformamide and then poured into a three-necked flask, and the carbonyl chloride fiber obtained in step 4 is added, wherein the molar ratio of the aminated graphene oxide to carbonyl chloride fiber is 1: 1. Heated in a constant temperature water bath at 70°C for 48 hours, washed with acetone until the filtrate was neutral, and grafted carbon fibers were obtained. The grafted carbon fibers were refluxed with 150ml of acetone for 24 hours, and then vacuum-dried at 60°C for 24 hours to obtain carbon fibers with graphene oxide grafted on the surface.

Claims (10)

1. the method for graphene oxide graft surface modified carbon fiber is characterized in that the method for graphene oxide graft surface modified carbon fiber is carried out as follows: 1. Graphite oxidation: Add graphite into the mixture of strong oxidizing acid and nitrate, cool to -5°C~0°C, stir and add potassium-containing strong oxidant at a speed of 50rpm~200rpm, and continue stirring for 4h~12h to obtain a mixed solution. Pour the solution into a water bath at 10°C to 50°C, continue to react for 40min to 60min, then add hot water at 90°C to 100°C, make the system boil and keep it for 20min to 40min, then add hydrogen peroxide solution with a volume concentration of 40% to 60%. , stirred at a speed of 100rpm to 500rpm until completely dissolved, then washed with ultrapure water for 3 to 6 times, filtered until there was no SO ₄ ^2- in the filter cake, and then freeze-dried at -35°C to obtain graphite oxide; Wherein the mass ratio of graphite and strong oxidizing acid is 1: (0.025～5); the mass ratio of graphite and nitrate is 1: (0.2～8); the mass ratio of graphite and potassium-containing strong oxidant is 1: (0.1～4 ); the mass ratio of graphite to hydrogen peroxide is 1: (0.125～4); 2. Stripping of graphite oxide mother liquor: Dissolve graphite oxide in a solvent, and ultrasonically vibrate for 0.5h-12h under the condition of ultrasonic power of 100W-1000W, then centrifuge under the condition of centrifuge rotation speed of 3000rpm-10000rpm, and freeze-dry at -35°C to obtain Graphene oxide powder; 3. Graphene oxide functionalization: Add 200ml THF solution, 8g NaBH ₄ and 0.1g I ₂ into the flask, stir to dissolve, then add 0.5g graphene oxide powder to react for 2 hours, and freeze-dry for 24 hours to obtain carboxyl graphene oxide; Weigh 0.0025g of carboxyl graphene oxide and 15ml of distilled water into a beaker, then add 5ml of silane coupling agent KH-550, react in a constant temperature water bath at 75°C for 6h, then centrifuge at 12000 rpm for 10min, pour off the supernatant Then add tetrahydrofuran and centrifuge at a speed of 12000 rpm for 10 min, pour off the supernatant, collect the aminated graphene oxide viscous liquid and freeze-dry to obtain aminated graphene oxide; 4. Surface functionalization of carbon fiber: Wind the carbon fiber on the square glass frame, then immerse the square glass frame into a beaker filled with mixed acid, the mixed acid is composed of concentrated nitric acid and concentrated sulfuric acid, wherein the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 3:1, and then the beaker Place on a magnetic stirrer, react at room temperature for 8 hours, wash with deionized water until the washing solution is neutral, and then vacuum dry at 100°C for 24 hours to obtain acid-oxidized carbon fibers; Fix the acid-oxidized carbon fiber with glass fiber, then add the acid-oxidized carbon fiber fixed with glass fiber, 160ml of thionyl chloride and 20ml of dimethylformamide into the three-necked flask, and react the three-necked flask at 70°C in a water bath After 48 hours, wash with acetone until the washing solution is neutral, and dry in vacuum at 70°C for 24 hours to obtain carbonyl chloride fibers; 5. Graphene oxide treatment on carbon fiber surface: Aminated graphene oxide is dissolved in dimethylformamide and then poured into a three-necked flask, and the carbonyl chloride fiber obtained in step 4 is added, wherein the molar ratio of the aminated graphene oxide to carbonyl chloride fiber is 1: 1. Heated in a constant temperature water bath at 70°C for 48 hours, washed with acetone until the filtrate was neutral, and grafted carbon fibers were obtained. The grafted carbon fibers were refluxed with 150ml of acetone for 24 hours, and then vacuum-dried at 60°C for 24 hours to obtain carbon fibers with graphene oxide grafted on the surface. 2. The method for grafting surface-modified carbon fibers of graphene oxide according to claim 1, wherein the strong oxidizing acid described in step 1 is concentrated sulfuric acid or perchloric acid. 3. according to the method for the described graphene oxide graft surface modification carbon fiber of claim 1, it is characterized in that the potassium-containing strong oxidizing agent described in step 1 is potassium permanganate or potassium perchlorate. 4. according to the method for the described graphene oxide graft surface modification carbon fiber of claim 1, it is characterized in that the nitrate described in step 1 is potassium nitrate, sodium nitrate, magnesium nitrate or calcium nitrate. 5. according to the method for the described graphene oxide grafting surface modification carbon fiber of claim 1, it is characterized in that the solvent described in step 2 is water, ethanol, acetone, ether, chloroform, benzene, toluene, ethylene glycol, tetrahydrofuran , N,N-dimethylformamide, petroleum ether, methyl acetate, ethyl acetate, carbon tetrachloride, organic chlorides, pyridine, ethylenediamine or carbon disulfide. 6. The method for grafting surface-modified carbon fibers with graphene oxide according to claim 1, 2, 3, 4 or 5, characterized in that the step 1 is cooled to -3°C. 7. according to the method for the described graphene oxide grafting surface modification carbon fiber of claim 1,2,3,4 or 5, it is characterized in that the mass ratio of graphite and strong oxidizing acid in step 1 is 1: 3; Graphite and nitric acid The mass ratio of salt is 1:2; the mass ratio of graphite and potassium-containing strong oxidant is 1:2; the mass ratio of graphite and hydrogen peroxide is 1:2. 8. The method for grafting graphene oxide surface-modified carbon fibers according to claim 1, 2, 3, 4 or 5, characterized in that adding a hydrogen peroxide solution with a volume concentration of 50% in step one. 9. The method of graphene oxide grafting surface modified carbon fiber according to claim 1, 2, 3, 4 or 5, characterized in that in step 2, ultrasonic vibration is performed under the condition that the ultrasonic power is 500W. 10. according to the method for the described graphene oxide graft surface modification carbon fiber of claim 1,2,3,4 or 5, it is characterized in that in step 2, centrifuge under the condition that centrifuge revolution is 5000rpm.

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