Preparation method of graphene dispersion liquid applied to fiber modification

Abstract

The invention discloses a preparation method of a graphene dispersion liquid applied to fiber modification, and belongs to the technical field of application of new graphene materials. In order to solve the problems that graphene is poor in dispersity and easy to agglomerate in the aramid mother liquor, the purpose of preparing the high-performance graphene reinforced aramid fiber composite material is achieved. The preparation method comprises the following steps: dispersing crystalline flake graphite into concentrated sulfuric acid, adding potassium perchlorate into a mixed solution, and reacting to obtain a mixed solution of potassium perchlorate / crystalline flake graphite / concentrated sulfuric acid; adding deionized water into the mixed solution obtained in the step 3 to obtain a mixed solution of deionized water, potassium perchlorate, crystalline flake graphite and concentrated sulfuric acid; a graphene oxide aqueous solution is obtained in a centrifugal cleaning mode and dispersed in N, N-dimethylacetamide, and graphene oxide dispersion liquid is obtained. And the stability of mechanical properties of the fibers can be ensured to be stable when the aramid fibers are produced on a large scale due to the uniformity of liquid dispersion stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of application of new graphene materials, and in particular relates to a method for preparing a graphene dispersion liquid used for fiber modification. Background Art

[0002] Organic high-performance fibers are a key development direction for the global fiber industry. While improving the mechanical properties of existing fibers, developing new fibers with integrated structural and functional properties is crucial for enhancing my country's international standing in aerospace and aviation. Carbon-based materials, such as graphene, possess excellent mechanical, electrical, and thermal properties and can be used to modify traditional organic high-performance fibers. By preparing carbon-based materials with varying physical and chemical properties and designing appropriate modification methods, the superior properties of these materials can be transferred to traditional fibers, resulting in carbon-based material-modified organic high-performance fibers with even higher mechanical, electrical, and thermal properties.

[0003] The commonly used method for preparing graphene-reinforced aramid fibers is to add a graphene dispersion to an aramid synthesis mother liquor, thereby introducing the graphene reinforcement during the subsequent aramid synthesis and spinning processes. However, due to its inherent van der Waals forces, graphene has difficulty dispersing uniformly in organic solvents, which in turn reduces its fiber reinforcement effect. To address the poor dispersion and easy agglomeration of graphene in aramid mother liquor, the goal is to produce high-performance graphene-reinforced aramid fiber composites. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of poor dispersion and easy agglomeration of graphene in aramid mother liquor and to achieve the goal of preparing high-performance graphene-reinforced aramid fiber composite materials.

[0005] The present invention provides a method for preparing a graphene dispersion for fiber modification. The method for obtaining the graphene oxide dispersion is as follows:

[0006] Step 1: Disperse flake graphite with a mesh size of 500-2000 mesh in concentrated sulfuric acid at a ratio of 10-100 mL / g of concentrated sulfuric acid to flake graphite; the temperature is 0-15° C., and the time is 10-30 min;

[0007] Step 2, adding potassium perchlorate to the mixed solution obtained in step 1 at a temperature range of 0°C to 5°C, and after complete addition, the ratio of oxidant to concentrated sulfuric acid is 20 to 200 mg / mL; the temperature is 4 to 15°C, and the time is 20 to 40 minutes. After the reaction is completed, a mixed solution of potassium perchlorate / flake graphite / concentrated sulfuric acid is obtained;

[0008] Step 3, reacting the mixed solution obtained in step 2 at a temperature of 30°C to 50°C for 60min to 180min;

[0009] Step 4, adding deionized water to the mixed solution obtained in step 3 at a temperature range of 0 to 5° C., wherein the ratio of deionized water to flake graphite is 20 mL / g to 100 mL / g, and then reacting at a temperature of 90° C. to 100° C. for 1 to 6 hours to obtain a mixed solution of deionized water, potassium perchlorate, flake graphite, and concentrated sulfuric acid;

[0010] Step 5: The mixed solution obtained in step 4 is centrifuged at a speed of 1000 rpm to 10000 rpm for 5 to 30 minutes, the upper liquid is poured out, the precipitate in the centrifuge tube is taken out and dissolved in deionized water, stirred evenly, and then poured into the centrifuge tube and centrifuged at a speed of 1000 rpm to 10000 rpm for 10 to 60 minutes. Repeat the above centrifugal washing operation 2 to 3 times until the pH of the supernatant in the centrifuge tube is 3 to 4, stop washing, pour out the supernatant, and take out the graphene oxide precipitated at the bottom;

[0011] Step 6: drying the graphene oxide aqueous solution and grinding it to obtain graphene oxide powder;

[0012] Step 7: Disperse the graphene oxide powder and N,N-dimethylacetamide at a ratio of 1 to 5 g / L using a microfluidizer or ultrasonic equipment to obtain a graphene oxide dispersion.

[0013] It is further defined that the ratio of concentrated sulfuric acid to flake graphite in step 1 is 60 mL / g, the temperature is 5° C., and the time is 15 min.

[0014] It is further defined that the ratio of oxidant / concentrated sulfuric acid in step 2 is 150 mg / mL, the temperature is 10° C., and the time is 30 min; the oxidant is potassium ferrite, potassium perchlorate, or potassium permanganate.

[0015] It is further defined that step 3 is carried out at 30°C to 50°C for 120 minutes.

[0016] It is further defined that the ratio of deionized water to flake graphite in step 4 is 50 mL / g, and then the reaction is carried out at a temperature of 95° C. and a time of 4 h.

[0017] It is further defined that the mixing equipment in step 7 adopts a microfluidizer with a pressure of 1000-3000 bar, or a sand mill with a speed of 1000-5000 rpm, or an ultrasonic power of 100-3000 W, an ultrasonic temperature of 10-40° C., and a time of 0.5 h to 20 h.

[0018] It is further defined that in step 5, pre-dispersion is performed by ultrasound.

[0019] It is further defined that the power of the ultrasound is 100-3000W and the time is 2 hours.

[0020] The present invention provides an application of the above method in modifying fibers.

[0021] Beneficial effects: The stability of the graphene oxide dispersion used for aramid III reinforcement is mainly related to the particle size of the graphene oxide. If the graphite oxide particle size is too large, burrs may appear on the fiber surface and the toughness may be attenuated during the spinning process, thereby affecting the apparent morphology and mechanical properties of the aramid fiber. The present invention adopts a chemical synthesis method to achieve the preparation of high-performance submicron graphene oxide dispersion by regulating the particle size of the graphite raw material, the oxidation process parameters and the dispersion treatment conditions. The preparation of high-performance graphene reinforced aramid fiber composites is achieved. The prepared graphene has good dispersibility, does not agglomerate inside the solution, and can maintain a stable fraction for a long time. Secondly, the uniformity of the dispersion stability can ensure the stability of the mechanical properties of the fiber during large-scale production of aramid. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Atomic force microscope photograph of graphene oxide according to Example 1 of the present invention;

[0023] Figure 2 A photograph of the sedimentation of the graphene oxide dispersion according to Example 1 of the present invention;

[0024] Figure 3 The kinetic instability curve (TSI) of the graphene oxide dispersion of Example 1 of the present invention;

[0025] Figure 4 This is the result of graphene oxide modified aramid III fiber.

[0026] Figure 5 Atomic force microscope photograph of graphene oxide according to Example 2 of the present invention;

[0027] Figure 6 A photograph of the sedimentation of the graphene oxide dispersion of Example 2 of the present invention;

[0028] Figure 7 The kinetic instability curve (TSI) of the graphene oxide dispersion of Example 2 of the present invention;

[0029] Figure 8 This is the result diagram of graphene oxide modified aramid III fiber;

[0030] Figure 9 Particle size distribution diagram of submicron graphene oxide according to Examples 3 and 4 of the present invention;

[0031] Figure 10 Actual photographs of the sedimentation of the submicron graphene oxide dispersions of Examples 3 and 4 of the present invention;

[0032] Figure 11 Dynamic instability curves (TSI) of the submicron graphene oxide dispersions of Examples 3 and 4 of the present invention. DETAILED DESCRIPTION

[0033] Example 1: Preparation method of submicron-sized graphene oxide dispersion in aramid system

[0034] Step 1: Evenly disperse 3 g of 2000-mesh flake graphite in 180 mL of concentrated sulfuric acid at a temperature of 5°C and stir evenly for 15 minutes to obtain a mixed solution of flake graphite / concentrated sulfuric acid;

[0035] Step 2: Add 15 g of potassium perchlorate in batches to the mixed solution obtained in step 1 at a temperature range of 0 to 5 ° C. After complete addition, react at 10 ° C. for 30 minutes to obtain a mixed solution of potassium perchlorate / flake graphite / concentrated sulfuric acid;

[0036] Step 3: The mixed solution obtained in step 2 is subjected to a medium-temperature reaction at a temperature of 35-40° C. for 120 min.

[0037] Step 4: Add 150 mL of deionized water to the mixed solution obtained in step 3 at a temperature of 0 to 5° C., and then perform a high-temperature reaction at 95° C. for 1 hour to generate graphene oxide.

[0038] Obtaining a mixed solution of deionized water / potassium perchlorate / flake graphite / concentrated sulfuric acid;

[0039] Step 5: Centrifuge the mixed solution obtained in step 4 at 10,000 rpm for 10 minutes. Pour off the supernatant, remove the precipitate (i.e., the generated graphene oxide) from the centrifuge tube, dissolve it in deionized water, stir it evenly, and then pour it back into the centrifuge tube and centrifuge for 20 minutes at 10,000 rpm. Repeat the centrifugation 2-3 times until the pH of the supernatant in the centrifuge tube reaches 3-4, then stop cleaning, pour off the supernatant, and remove the graphene oxide precipitated at the bottom.

[0040] Step 6: drying the graphene oxide at 60° C. and grinding the graphene oxide to obtain graphene oxide powder;

[0041] Step 7: 1 g of graphene oxide powder was added to 1 L of N,N-dimethylacetamide (DMAC) and ultrasonically dispersed at a temperature of 20° C., a power of 400 W, and a time of 2 h. After the ultrasonication, a DMAC dispersion of small-sized graphene oxide was obtained.

[0042] The atomic force microscope photograph of the submicron-sized graphene oxide dispersion suitable for aramid III system in Example 1 of the present invention is as follows: Figure 1 As shown, Figure 1 -a is an atomic force microscopy image of the dispersion of GO-DMAC system under 400W ultrasound and 20℃ ultrasound temperature. Figure 1 -b is an atomic force microscopy image of the dispersion of the GO-DMAC system under 400W ultrasound and 60°C ultrasound temperature.

[0043] Depend on Figure 1 As far as we know, graphene oxide exists in the form of flakes, and no agglomeration is observed. The particle size is 200-500nm, reaching the submicron level, and the flake thickness is 2nm-4nm, reaching the thickness of graphene, which shows that the effect of preparing graphene oxide by chemical reaction is good. Figure 1 As far as we know, there are a lot of agglomerations in the dispersion. This is because the ultrasonic temperature affects the surface tension of DMAC. When the ultrasonic temperature reaches 60 °C, the surface tension decreases, which reduces the cavitation effect of the ultrasound, resulting in a large amount of GO not being completely dispersed into the dispersion, and thus a large amount of agglomerations occur.

[0044] The actual photograph of the sedimentation of the submicron-sized graphene oxide dispersion suitable for the aramid III system in Example 1 of the present invention is as follows: Figure 2 As shown, Figure 2 -a is a photograph of the sedimentation of the dispersion of the GO-DMAC system under 400W ultrasound and 20°C ultrasound temperature. Figure 2 -b is a photograph of the sedimentation of the dispersion of the GO-DMAC system under 400W ultrasound and 60°C ultrasound temperature.

[0045] Depend on Figure 2 -a, the samples all have uniform color after 30 days, which shows that the graphene oxide dispersion has good stability. Figure 2 -b sample showed obvious sedimentation phenomenon, which was due to the presence of a large number of agglomerates in the dispersion, which enlarged the GO sheets, reduced the dispersibility of GO in DMAC, and caused precipitation.

[0046] The kinetic instability curve (TSI) of the submicron-sized graphene oxide dispersion used in the aramid III system in Example 1 of the present invention is as follows: Figure 3 Sample A refers to the dispersion of the GO-DMAC system at 400W ultrasonication and 20°C ultrasonic temperature, and sample B refers to the dispersion of the GO-DMAC system at 400W ultrasonication and 60°C ultrasonic temperature.

[0047] A lower TSI value indicates greater dispersion stability. Sample A shows a lower TSI value, indicating greater dispersion stability. Furthermore, the slope of the TSI curve represents the aggregation of the dispersion during quiescence; a higher slope indicates greater GO aggregation within the dispersion. Sample A shows a lower slope, indicating that this type of graphene oxide dispersion is stable for extended storage and exhibits excellent dispersibility.

[0048] Aramid III fiber was added to the dispersion of graphene oxide in an organic system at a concentration of 1 g / L, an ultrasonic temperature of 20°C, and an ultrasonic time of 2 h.

[0049] The mechanical properties of the aramid fiber of the submicron-sized graphene oxide dispersion used in the aramid III system in Example 1 of the present invention are as follows: Figure 4 shown. Figure 2 -a is the breaking strength test of the dispersion of GO-DMAC system combined with aramid III system under 400W ultrasound and ultrasound temperature of 20℃. Figure 2 -a is the breaking strength test of the GO-DMAC system combined with the aramid III system under 400W ultrasound and 60℃ ultrasound temperature.

[0050] By comparison, it was found that the submicron-sized graphene dispersion at a strong ultrasonic temperature of 20°C had a greater average breaking strength of 37.84 cN / dtex, which shows that the submicron-sized graphene oxide modified aramid III fiber has high strength and high toughness, indicating that the submicron-sized graphene oxide is suitable for the aramid III system.

[0051] Example 2: Preparation method of submicron-sized graphene oxide dispersion in aramid system

[0052] Step 1: At a temperature of 5°C, 5 g of 500-mesh flake graphite was evenly dispersed in 300 mL of concentrated sulfuric acid and stirred for 15 minutes to obtain a mixed solution of flake graphite / concentrated sulfuric acid;

[0053] Step 2: Add 25 g of potassium perchlorate to the mixed solution obtained in step 1 in batches at a temperature range of 0 to 5 ° C. After complete addition, react at 10 ° C. for 30 minutes to obtain a mixed solution of potassium perchlorate / flake graphite / concentrated sulfuric acid;

[0054] Step 3: The mixed solution obtained in step 2 is subjected to a medium-temperature reaction at a temperature of 35-40° C. for 120 min.

[0055] Step 4: Add 250 mL of deionized water to the mixed solution obtained in step 3 at a temperature of 0 to 5° C., and then perform a high-temperature reaction at 95° C. for 1 h to generate graphene oxide.

[0056] Step 5: Centrifuge the mixed solution obtained in step 4 at 10,000 rpm for 10 minutes. Pour off the supernatant, remove the precipitate (i.e., the generated graphene oxide) from the centrifuge tube, dissolve it in deionized water, stir it evenly, and then pour it back into the centrifuge tube and centrifuge for 20 minutes at 10,000 rpm. Repeat the centrifugation 2-3 times until the pH of the supernatant in the centrifuge tube reaches 3-4, then stop cleaning, pour off the supernatant, and remove the graphene oxide precipitated at the bottom.

[0057] Step 6: drying the graphene oxide at 60° C. and grinding the graphene oxide to obtain graphene oxide powder;

[0058] Step 7: 3 g of graphene oxide powder was added to 1 L of N,N-dimethylacetamide (DMAC) and ultrasonically dispersed at a temperature of 40° C., an ultrasonic power of 800 W, and a ultrasonic time of 2 h. After the ultrasonication, a DMAC dispersion of small-sized graphene oxide was obtained.

[0059] The atomic force microscope photograph of the submicron-sized graphene oxide dispersion suitable for aramid III system in Example 2 of the present invention is as follows: Figure 5 As shown, Figure 5 -a is an atomic force microscopy image of the dispersion of GO-DMAC system under 800W ultrasound and 40℃ ultrasound temperature. Figure 5 -b is an atomic force microscopy image of the dispersion of the GO-DMAC system under 800W ultrasound and 70°C ultrasound temperature.

[0060] Depend on Figure 5 As far as we know, graphene oxide exists in the form of flakes, and no agglomeration is observed. The particle size is 200-800nm, reaching the submicron level, and the flake thickness is 2nm-4nm, reaching the thickness of graphene, which shows that the effect of preparing graphene oxide by chemical reaction is good. Figure 5 As far as we know, there are a lot of agglomerates in the dispersion. This is because the ultrasonic temperature affects the surface tension of DMAC. When the ultrasonic temperature reaches 70 °C, the surface tension decreases, which reduces the cavitation effect generated by ultrasound, resulting in a large amount of GO not being completely dispersed into the dispersion, resulting in a large amount of agglomerates.

[0061] The actual photograph of the sedimentation of the submicron-sized graphene oxide dispersion suitable for the aramid III system in Example 2 of the present invention is as follows: Figure 6 As shown, Figure 6 -a is a photograph of the sedimentation of the dispersion of the GO-DMAC system under 800W ultrasound and 40°C ultrasound temperature. Figure 6-b is a photograph of the sedimentation of the dispersion of the GO-DMAC system under 800W ultrasound and 70°C ultrasound temperature.

[0062] Depend on Figure 6 -a, the samples all have uniform color after 30 days, which shows that the graphene oxide dispersion has good stability. Figure 6 -b sample showed obvious sedimentation phenomenon, which was due to the presence of a large number of agglomerates in the dispersion, which reduced the dispersibility of GO in DMAC and caused precipitation.

[0063] The dynamic instability curve (TSI) of the submicron-sized graphene oxide dispersion used in the aramid III system in Example 2 of the present invention is as follows: Figure 7 Sample A refers to the dispersion of the GO-DMAC system at 800W ultrasonication and 40°C ultrasonic temperature, and sample B refers to the dispersion of the GO-DMAC system at 800W ultrasonication and 70°C ultrasonic temperature.

[0064] A lower TSI value indicates greater dispersion stability. Sample A shows a lower TSI value, indicating greater dispersion stability. Furthermore, the slope of the TSI curve represents the amount of GO aggregation during the static phase of the dispersion. A higher slope indicates greater GO aggregation within the dispersion. Sample A shows a lower slope, indicating that this type of graphene oxide dispersion can be stored stably for extended periods and exhibits excellent stability.

[0065] Aramid III fiber was added to the dispersion of graphene oxide in an organic system at a concentration of 3 g / L, an ultrasonic temperature of 40°C, and an ultrasonic time of 2 h.

[0066] The mechanical properties of the aramid fiber of the submicron-sized graphene oxide dispersion used in the aramid III system in Example 1 of the present invention are as follows: Figure 4 shown. Figure 2 -a is the breaking strength test of the dispersion of GO-DMAC system combined with aramid III system under 800W ultrasound and ultrasound temperature of 40℃. Figure 2 -a is the breaking strength test of the GO-DMAC system combined with the aramid III system under 800W ultrasound and 70℃ ultrasound temperature.

[0067] By comparison, it was found that the submicron-sized graphene dispersion at a strong ultrasonic temperature of 40°C had a greater average breaking strength of 34.75 cN / dtex, which shows that the submicron-sized graphene oxide modified aramid III fiber has high strength and high toughness, indicating that the submicron-sized graphene oxide is suitable for the aramid III system.

[0068] Example 3: The preparation method of the submicron-sized graphene oxide dispersion suitable for the aramid fiber synthesis system in this example is achieved by the following steps:

[0069] Step 1: Take 200g of 2000-mesh flake graphite and evenly disperse it in 4L concentrated sulfuric acid. Stir evenly for 10 minutes to obtain a mixed solution of flake graphite / concentrated sulfuric acid. The temperature is 10°C and the time is 10 minutes.

[0070] Step 2: Add 10 g of potassium perchlorate in batches to the mixed solution obtained in step 1 at a temperature of -5°C. After complete addition, carry out a low-temperature reaction at a temperature of -5°C for 1 hour. After the reaction is completed, a mixed solution of potassium perchlorate / flake graphite / concentrated sulfuric acid is obtained;

[0071] Step 3: subject the mixed solution obtained in step 2 to a medium-temperature chemical reaction at 35° C. for 2 h.

[0072] Step 4: Add 5 L of deionized water to the mixed solution obtained in step 3 at a temperature of 35° C., and then perform a high-temperature chemical reaction at a temperature of 90° C. for 2 h to obtain a mixed solution of deionized water / potassium perchlorate / flake graphite / concentrated sulfuric acid;

[0073] Step 5: The mixed solution obtained in step 4 is cleaned using a filter press cleaning device to obtain a mixed solution with an acidity of 2%, and the mixed solution is pre-dispersed by ultrasonic treatment for 2 h (ultrasonic power of 100-3000 W) to obtain a graphene aqueous solution;

[0074] Step 6: drying the graphene oxide aqueous solution and grinding it to obtain graphene oxide powder.

[0075] Step 7: The graphene oxide powder and N,N-dimethylacetamide composite fiber system (DMAC) are prepared into a graphene oxide dispersion at a concentration of 1 g / L, and dispersed using a microfluidizer at a pressure of 2000 bar for 2 hours to obtain a submicron graphene dispersion.

[0076] Example 4: The preparation method of the submicron-sized graphene oxide dispersion suitable for the aramid fiber synthesis system in this example is achieved by the following steps:

[0077] Step 1: Take 200g of 2000-mesh flake graphite and evenly disperse it in 10L of concentrated sulfuric acid. Stir evenly for 15 minutes to obtain a mixed solution of flake graphite / concentrated sulfuric acid. The temperature is 15°C and the time is 15 minutes.

[0078] Step 2: Add 10 g of potassium perchlorate in batches to the mixed solution obtained in step 1 at a temperature of 5° C. After complete addition, perform a low-temperature reaction at a temperature of 0° C. for 1 h. After the reaction is completed, a mixed solution of potassium perchlorate / flake graphite / concentrated sulfuric acid is obtained;

[0079] Step 3: subject the mixed solution obtained in step 2 to a medium-temperature chemical reaction at 50° C. for 3 h.

[0080] Step 4: Add 5 L of deionized water to the mixed solution obtained in step 3 at a temperature of 20° C., and then perform a high-temperature chemical reaction at a temperature of 95° C. for 2 hours to obtain a mixed solution of deionized water / potassium perchlorate / flake graphite / concentrated sulfuric acid;

[0081] Step 5: The mixed solution obtained in step 4 is cleaned using a filter press cleaning device to obtain a mixed solution with an acidity of 3%, and the mixed solution is pre-dispersed by ultrasonication for 2 h (ultrasonic power of 100-3000 W) to obtain a graphene aqueous solution;

[0082] Step 6: drying the graphene oxide aqueous solution and grinding it to obtain graphene oxide powder.

[0083] Step 7: The graphene oxide powder and N,N-dimethylacetamide composite fiber system (DMAC) are configured into a graphene oxide dispersion at a concentration of 1 g / L, and a sand mill is used for dispersion treatment at a speed of 1500 rpm for 5 hours to obtain a submicron graphene dispersion.

[0084] The particle size distribution diagram of the submicron-sized graphene oxide dispersion suitable for aramid fiber synthesis system in Example 3 and Example 4 of the present invention is as follows: Figure 9 As shown. Figure 9 As we know, the particle size of graphene oxide ranges from 30 to 800 nm, reaching the submicron level.

[0085] The actual photos of the sedimentation of submicron-sized graphene oxide dispersions suitable for aramid fiber synthesis systems in Examples 3 and 4 of the present invention are as follows: Figure 10 As shown by Figure 10 As we know, the color of the sample is uniform after 30 days, which shows that the graphene oxide dispersion has good stability.

[0086] The dynamic instability curve (TSI) of the submicron-sized graphene oxide dispersion used in the aramid fiber synthesis system in Examples 3 and 4 of the present invention is as follows: Figure 11 As shown. Figure 11As we know, a TSI value less than 0.2 indicates good dispersion stability. The submicron graphene oxide dispersion has the lowest TSI value, indicating good stability. This indicates that the submicron graphene oxide dispersion prepared by this method is effective and suitable for batch production.

Claims

1. A method for preparing a graphene dispersion for fiber modification, characterized in that: The method for obtaining graphene oxide dispersion is as follows: Step 1: Disperse flake graphite with a mesh size of 500-2000 mesh in concentrated sulfuric acid at a ratio of 10-100 mL / g of concentrated sulfuric acid to flake graphite; the temperature is 0-15° C., and the time is 10-30 min; Step 2, adding potassium perchlorate to the mixed solution obtained in step 1 at a temperature range of 0°C to 5°C, and after complete addition, the ratio of oxidant to graphite is 1g / g to 5g / g; the temperature is 4-15°C, and the time is 20-40 minutes. After the reaction is completed, a mixed solution of potassium perchlorate / flake graphite / concentrated sulfuric acid is obtained; Step 3, reacting the mixed solution obtained in step 2 at a temperature of 30°C to 50°C for 60min to 180min; Step 4: adding deionized water to the mixed solution obtained in step 3 at a temperature range of 0 to 5° C., wherein the ratio of deionized water to flake graphite is 20 mL / g to 100 mL / g, and then reacting at a temperature of 90 to 100° C. for 30 min to 3 h to generate graphene oxide; Step 5: The mixed solution obtained in step 4 is centrifuged at a speed of 1000 rpm to 10000 rpm for 5 to 30 minutes, the upper liquid is poured out, the precipitate in the centrifuge tube is taken out and dissolved in deionized water, stirred evenly, and then poured into the centrifuge tube and centrifuged at a speed of 1000 rpm to 10000 rpm for 10 to 60 minutes. Repeat the above centrifugal washing operation 2 to 3 times until the pH of the supernatant in the centrifuge tube is 3 to 4, stop washing, pour out the supernatant, and take out the graphene oxide precipitated at the bottom; Step 6: drying the graphene oxide obtained in step 5 and grinding it to obtain graphene oxide powder; Step 7: Disperse the graphene oxide powder and N,N-dimethylacetamide at a ratio of 1 to 5 g / L using a microfluidizer or ultrasonic equipment to obtain a graphene oxide dispersion.

2. The method according to claim 1, characterized in that Step 1: The ratio of concentrated sulfuric acid to flake graphite is 60 mL / g, the temperature is 5° C., and the time is 15 min.

3. The method according to claim 1, characterized in that In step 2, the ratio of oxidant to graphite is 5 g / g, the temperature is 10° C., and the time is 30 min; the oxidant is potassium ferrite, potassium perchlorate, and potassium permanganate.

4. The method according to claim 1, wherein In step 3, the temperature is 30° C. to 50° C. for 120 min.

5. The method according to claim 1, characterized in that In step 4, the ratio of deionized water to flake graphite is 50 mL / g, and then the reaction is carried out at a temperature of 95° C. for 1 h.

6. The method according to claim 1, characterized in that In step 7, graphene oxide powder and N,N-dimethylacetamide are prepared in a ratio of 1 to 5 g / L, the microfluidizer pressure is 1000 to 3000 bar, or the ultrasonic power is 100-3000 W, the time is 0.5 h to 3 h, and the ultrasonic temperature is 10 to 40 ° C.

7. The method according to claim 1, characterized in that In step 5, pre-dispersion is performed by ultrasound.

8. The method according to claim 7, characterized in that The power of the ultrasound is 100-3000W, and the time is 2 hours.

9. Use of the method according to any one of claims 1 to 8 in modifying fibers.

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