A method for preparing high-strength pure graphene fibers by using a Tesla valve microchannel

Abstract

The application discloses a method for preparing high-strength pure graphene fibers by using Tesla valve microchannels, and the method comprises the following steps: preparing graphene oxide by an improved Hummers method, layering and centrifugal separating the graphene oxide by peeling, and concentrating to obtain a graphene oxide aqueous solution; adding a DMF solvent into the graphene oxide aqueous solution, stirring uniformly, and then centrifugal separating to obtain a DMF solution of the graphene oxide; performing microfluid wet spinning on the DMF solution of the graphene oxide by using a Tesla valve microchannel to obtain graphene oxide fibers; and performing a reduction reaction on the graphene oxide fibers, and the high-strength pure graphene fibers are obtained. The special structure of the Tesla valve microchannel is combined with the wet spinning technology, the preparation of the high-orientation high-strength pure graphene fibers is successfully realized, and the problem of low fiber orientation in the traditional fiber preparation method is effectively overcome by optimizing the microfluid wet spinning process and post-processing technology.

Description

Technical Field

[0001] This invention belongs to the fields of microfluidics technology and graphene fiber preparation technology, and specifically relates to a method for preparing high-strength pure graphene fibers using Tesla valve microchannels. Background Technology

[0002] With the development of science and technology and the progress of society, people's demand for new materials is increasing, especially lightweight high-strength materials, which have important application value in high-tech fields such as aerospace, national defense, and new energy. Lightweight high-strength materials can not only improve the performance and efficiency of equipment, but also reduce energy consumption and environmental pollution, contributing to the achievement of low-carbon economic development goals. Therefore, researching and developing lightweight high-strength materials with excellent mechanical properties is one of the important topics in materials science today.

[0003] Graphene sheets possess excellent mechanical, electrical, thermal, and optical properties, and their microscopic properties can be macroscopically realized through macroscopic assembly processes. Graphene-based fibers have seen significant development in recent years due to their unique structure and superior performance. Compared to graphene-based aerogels and membranes, graphene-based fibers exhibit significantly superior mechanical and electrical properties and can be bent, knotted, or woven into flexible electronic textiles. Based on the lyotropic liquid crystal phenomenon of graphene oxide, graphene fibers exhibit long-range ordered structural characteristics, along with larger crystalline regions and higher crystallinity, thus holding the promise of surpassing carbon fiber performance and becoming a structurally and functionally integrated fiber material. Wet spinning is currently the optimal method for preparing high-strength graphene fibers. However, there are certain problems in the current preparation of high-strength graphene fibers: the orientation degree of graphene sheets in graphene fibers is low, resulting in low mechanical strength of the fibers, which cannot meet the needs of practical applications; therefore, it is necessary to develop a method for preparing high-strength graphene fibers. This method can improve the alignment degree of graphene sheets, the orientation degree and mechanical properties of the fibers by designing microstructures for microfluidic wet spinning and stretching the fibers throughout the spinning process.

[0004] Microfluidics is a technology that processes tiny fluids using microchannels. Microfluidic wet spinning involves the flow of fluids within microchannels with different structures. In this process, by designing different channel shapes, the fluid composition and flow rate can be controlled, enabling the arrangement of two-dimensional material sheets and the rapid forming, orientation adjustment, and precise structural control of fibers. Summary of the Invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for preparing high-strength graphene fibers by wet spinning using a Tesla valve microchannel, which overcomes the problems of low fiber orientation and poor mechanical properties of graphene fibers in the prior art, and prepares pure graphene fibers with ordered orientation of microstructure and excellent mechanical properties.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing high-strength pure graphene fibers using Tesla valve microchannels includes the following steps:

[0008] (1) Graphene oxide was prepared by the modified Hummers method. 3g of flake graphite was placed in an Erlenmeyer flask, and 40mL of phosphoric acid and 360mL of concentrated sulfuric acid were added respectively. The mixture was stirred in an ice bath in a water bath for 30min, and 18g of potassium permanganate was slowly added to it for oxidation for 8 hours. After oxidation, the mixture was peeled to separate into layers, centrifuged, and concentrated to obtain an aqueous solution of graphene oxide.

[0009] (2) Add DMF solvent to the graphene oxide aqueous solution in step (1), stir evenly and then centrifuge to obtain DMF solution of graphene oxide.

[0010] (3) Preparation of pure graphene oxide fibers: Graphene oxide DMF solution was spun by microfluidic spinning using a Tesla valve microchannel to obtain graphene oxide fibers.

[0011] (4) Preparation of pure graphene fiber: The graphene oxide fiber obtained in step (3) is subjected to a reduction reaction to obtain the pure graphene fiber.

[0012] Furthermore, in step (1), the concentration of the obtained graphene oxide aqueous solution is 10 mg / mL to 20 mg / mL, preferably 15 mg / mL.

[0013] Further, in step (2), the centrifuge speed is 8000-10000 rpm, the centrifugation time is 0.5-1 hour, the centrifugation is repeated 3-5 times, and the supernatant is discarded after each centrifugation; the concentration of the obtained graphene oxide DMF solution is 10mg / mL-20mg / mL, preferably 15mg / mL.

[0014] Further, in step (3), the Tesla valve microchannel comprises an inclined, continuously alternating, and obstructed curved conduit; the total length L of the Tesla valve microchannel is 8–23 mm, the inlet width is 1–2 mm, the outlet width is 0.5–1 mm, and the channel depth is 1–3 mm. Preferably, the total length L of the Tesla valve microchannel is 11 mm, the inlet width is 1 mm, the outlet width is 0.7 mm, and the channel depth is 1 mm.

[0015] Further, in step (3), the microfluidic wet spinning method is as follows: the DMF solution of the graphene oxide is injected into the coagulation bath solution through the Tesla valve microchannel spinning needle, and coagulated under the action of the coagulation bath to obtain the graphene oxide fiber.

[0016] Furthermore, in step (3), the injection pump is used to control the propulsion speed of the graphene oxide DMF solution in the Tesla valve microchannel to be 0.2 to 0.4 mL / min, with a preferred propulsion speed of 0.3 mL / min.

[0017] Further, in step (3), the coagulation bath solution is a mixed solution of acetone and ethyl acetate in a volume ratio of 1:3 to 4, preferably 1:3; the graphene oxide fiber is soaked in the coagulation bath solution for 20 to 30 minutes, and then taken out for stretching and drying.

[0018] Further, in step (4), the reducing agent used in the reduction reaction is any one of 40-60% hydroiodic acid aqueous solution, vitamin C aqueous solution or hydrazine hydrate aqueous solution, preferably 50% hydroiodic acid aqueous solution; the temperature of the reduction reaction is 50-60℃, preferably 60℃; the reaction time is 4-8 hours, preferably 4 hours.

[0019] Furthermore, the present invention also claims protection for the high-strength pure graphene fibers prepared by the above-described preparation method.

[0020] Furthermore, the two-dimensional sheets in the pure graphene fiber have a highly ordered oriented arrangement, which significantly improves the fiber's mechanical strength. The tensile strength of the pure graphene fiber is not less than 504 MPa, and the elongation at break is not less than 6.8%.

[0021] Beneficial effects:

[0022] (1) This invention improves the existing microfluidic chip structure by adopting the special structure of Tesla valve microchannel and combining it with wet spinning technology to successfully prepare high-orientation, high-strength pure graphene fibers. By optimizing the microfluidic wet spinning process and post-processing technology, the problem of low fiber orientation in traditional fiber preparation methods is effectively overcome, making graphene fibers more flexible in application and providing a new way for the development and application of graphene fibers.

[0023] (2) The pure graphene fiber prepared by this invention has high orientation, high mechanical strength and high toughness, and can be used as an ideal choice for lightweight and high-strength materials. The excellent tensile properties of the fiber enable it to withstand a certain weight. This behavior can even be bent, knotted or woven into various fabrics, and it has chemical stability, which provides a wider range of applications for high-performance materials such as flexible wearables and functional fabrics.

[0024] (3) This invention provides a method for assembling high-strength pure graphene fibers using Tesla valve microchannels. Compared with traditional ordinary spinning needles and unstructured flat microchannel wet spinning methods, when using this invention, the two-dimensional graphene oxide sheets are subjected to strong shearing action, the sheets are effectively stretched, the sheet orientation is improved, and the effect is significant. In addition, this method has the advantages of simple process, low cost, strong controllability, and large-scale production capability, which makes the preparation method of this invention more economical and scientific. Attached Figure Description

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0026] Figure 1 This is a cross-sectional structural diagram of the Tesla valve microchannel device of the present invention.

[0027] Figure 2 This is a tensile stress-strain diagram of the pure graphene fiber prepared in Example 1 of the present invention.

[0028] Figure 3 This is a scanning electron microscope image of the morphology of the pure graphene fibers prepared in Example 2 of the present invention.

[0029] Figure 4 This is a tensile stress-strain diagram of the pure graphene fiber prepared in Example 2 of the present invention.

[0030] Figure 5 This is a tensile stress-strain diagram of the pure graphene fiber prepared in Example 3 of the present invention.

[0031] Figure 6This is a tensile stress-strain diagram of the pure graphene fiber prepared in Example 4 of the present invention.

[0032] Figure 7 This is a tensile stress-strain diagram of the pure graphene fiber prepared in Example 5 of the present invention.

[0033] Figure 8 This is a tensile stress-strain diagram of the pure graphene fiber prepared in Example 6 of the present invention.

[0034] Figure 9 This is a scanning electron microscope image of the morphology of the pure graphene fibers prepared in Comparative Example 1 of this invention.

[0035] Figure 10 This is a tensile stress-strain diagram of the pure graphene fiber prepared in Comparative Example 1 of this invention. Detailed Implementation

[0036] The present invention can be better understood from the following embodiments.

[0037] In the following embodiments, the fiber mechanical property testing method is as follows: The fiber mechanical property test is performed on a universal tensile testing machine. First, the fiber is cut to a certain length, the monofilament is fixed between the clamps, and the sample is straightened. Second, the test parameters are set. For ribbon fibers, the cross-sectional length and width need to be recorded (the cross-sectional morphology of different fiber sections is photographed by scanning electron microscopy, and then the data are statistically averaged). The tensile rate is set to 1 mm / min. Finally, the testing machine is started and loaded until the monofilament fails. The load-elongation curve is recorded. If the monofilament fails in the clamp, the data is considered invalid and should be discarded. The sample is resampled and tested. The fiber sample is considered valid only if it breaks in the middle after being subjected to force. At least ten valid data points are obtained for each group of samples, and then the average value is taken.

[0038] The Tesla valve microchannel structure used in the following embodiments is as follows: Figure 1 As shown, the circuit includes inclined, continuously alternating, and obstructed curved conduits. The preferred total length L of the Tesla valve microchannel is 11 mm, the inlet width is 1 mm, the outlet width is 0.7 mm, and the channel depth is 1 mm.

[0039] Example 1

[0040] A method for preparing high-strength pure graphene fibers using Tesla valve microchannel assembly, the specific preparation method including the following steps:

[0041] (1) Take 3g of 200-mesh graphite powder to prepare graphite oxide by the modified Hummers method, then mechanically shear and peel it to make it into layers, centrifuge to separate it into graphene oxide slurry, and finally concentrate it to obtain an aqueous solution of graphene oxide with a concentration of 15mg / mL.

[0042] (2) Add 20 mL of DMF solvent to 5 mL of graphene oxide aqueous solution, stir evenly, centrifuge at 10000 rpm for 30 min, discard the supernatant, repeat the above steps 3 to 5 times, take out the lower layer solution and stir evenly to obtain a DFM solution of graphene oxide with a concentration of 15 mg / mL.

[0043] (3) The graphene oxide DMF spinning solution was injected into a coagulation bath solution of acetone and ethyl acetate through a Tesla valve microchannel with a valve channel to carry out microfluidic wet spinning at an injection speed of 0.3 mL / min to obtain graphene oxide fibers.

[0044] (4) Finally, the graphene oxide fibers obtained in step (3) are chemically reduced under the action of hydroiodic acid reducing agent. The reduction temperature is 60℃ and the reduction time is 4h to obtain graphene fibers. After mechanical property testing, such as... Figure 2 As shown, the graphene fiber prepared in this embodiment has a tensile strength of up to 549 MPa and an elongation at break of 6.8%.

[0045] Example 2

[0046] A method for preparing high-strength pure graphene fibers using Tesla valve microchannel assembly, the specific preparation method including the following steps:

[0047] (1) Take 3g of 200-mesh graphite powder to prepare graphite oxide by the modified Hummers method, then mechanically shear and peel it to make it into layers, centrifuge to separate it into graphene oxide slurry, and finally concentrate it to obtain an aqueous solution of graphene oxide with a concentration of 15mg / mL.

[0048] (2) Add 20 mL of DMF solvent to 5 mL of graphene oxide aqueous solution, stir evenly, centrifuge at 10000 rpm for 30 min, discard the supernatant, repeat the above steps 3 to 5 times, take out the lower layer solution and stir evenly to obtain a DFM solution of graphene oxide with a concentration of 15 mg / mL.

[0049] (3) The graphene oxide DMF spinning solution was injected into a coagulation bath solution of acetone and ethyl acetate through a Tesla valve microchannel with two valve channels to carry out microfluidic wet spinning at an injection speed of 0.3 mL / min to obtain graphene oxide fibers.

[0050] (4) Finally, the graphene oxide fibers obtained in step (3) are chemically reduced under the action of hydroiodic acid reducing agent. The reduction temperature is 60℃ and the reduction time is 4h to obtain graphene fibers. Figure 3 As shown, from Figure 3As can be seen, the fibers prepared in this embodiment have good continuity, fewer surface wrinkles, and the graphene sheets are arranged in a regular and orderly manner with high orientation. Mechanical property tests show that... Figure 4 As shown, the graphene fiber prepared in this embodiment has a tensile strength of up to 1084 MPa and an elongation at break of 11.5%.

[0051] Example 3

[0052] A method for preparing high-strength pure graphene fibers using Tesla valve microchannel assembly, the specific preparation method including the following steps:

[0053] (1) Take 3g of 200-mesh graphite powder to prepare graphite oxide by the modified Hummers method, then mechanically shear and peel it to make it into layers, centrifuge to separate it into graphene oxide slurry, and finally concentrate it to obtain an aqueous solution of graphene oxide with a concentration of 15mg / mL.

[0054] (2) Add 20 mL of DMF solvent to 5 mL of graphene oxide aqueous solution, stir evenly, centrifuge at 10000 rpm for 30 min, discard the supernatant, repeat the above steps 3 to 5 times, take out the lower layer solution and stir evenly to obtain a DFM solution of graphene oxide with a concentration of 15 mg / mL.

[0055] (3) The graphene oxide DMF spinning solution was injected into a coagulation bath solution of acetone and ethyl acetate through a Tesla valve microchannel with three valve channels to carry out microfluidic wet spinning at an injection speed of 0.3 mL / min to obtain graphene oxide fibers.

[0056] (4) Finally, the graphene oxide fibers obtained in step (3) are chemically reduced under the action of hydroiodic acid reducing agent. The reduction temperature is 60℃ and the reduction time is 4h to obtain graphene fibers. After mechanical property testing, such as... Figure 5 As shown, the graphene fiber prepared in this embodiment has a tensile strength of up to 679 MPa and an elongation at break of 8.6%.

[0057] Example 4

[0058] A method for preparing high-strength pure graphene fibers using Tesla valve microchannel assembly, the specific preparation method including the following steps:

[0059] (1) Take 3g of 200-mesh graphite powder to prepare graphite oxide by the modified Hummers method, then mechanically shear and peel it to make it into layers, centrifuge to separate it into graphene oxide slurry, and finally concentrate it to obtain an aqueous solution of graphene oxide with a concentration of 15mg / mL.

[0060] (2) Add 20 mL of DMF solvent to 5 mL of graphene oxide aqueous solution, stir evenly, centrifuge at 10000 rpm for 30 min, discard the supernatant, repeat the above steps 3 to 5 times, take out the lower layer solution and stir evenly to obtain a DFM solution of graphene oxide with a concentration of 15 mg / mL.

[0061] (3) The graphene oxide DMF spinning solution was injected into a coagulation bath solution of acetone and ethyl acetate through a Tesla valve microchannel with four valve channels to carry out microfluidic wet spinning at an injection speed of 0.3 mL / min to obtain graphene oxide fibers.

[0062] (4) Finally, the graphene oxide fibers obtained in step (3) are chemically reduced under the action of hydroiodic acid reducing agent. The reduction temperature is 60℃ and the reduction time is 4h to obtain graphene fibers. After mechanical property testing, such as... Figure 6 As shown, the graphene fiber prepared in this embodiment has a tensile strength of up to 957 MPa and an elongation at break of 13.5%.

[0063] Example 5

[0064] A method for preparing high-strength pure graphene fibers using Tesla valve microchannel assembly, the specific preparation method including the following steps:

[0065] (1) Take 3g of 200-mesh graphite powder to prepare graphite oxide by the modified Hummers method, then mechanically shear and peel it to make it into layers, centrifuge to separate it into graphene oxide slurry, and finally concentrate it to obtain an aqueous solution of graphene oxide with a concentration of 15mg / mL.

[0066] (2) Add 20 mL of DMF solvent to 5 mL of graphene oxide aqueous solution, stir evenly, centrifuge at 10000 rpm for 30 min, discard the supernatant, repeat the above steps 3 to 5 times, take out the lower layer solution and stir evenly to obtain a DFM solution of graphene oxide with a concentration of 15 mg / mL.

[0067] (3) The graphene oxide DMF spinning solution was injected into a coagulation bath solution of acetone and ethyl acetate through a Tesla valve microchannel with five valve channels to carry out microfluidic wet spinning at an injection speed of 0.3 mL / min to obtain graphene oxide fibers.

[0068] (4) Finally, the graphene oxide fibers obtained in step (3) are chemically reduced under the action of hydroiodic acid reducing agent. The reduction temperature is 60℃ and the reduction time is 4h to obtain graphene fibers. After mechanical property testing, such as... Figure 7 As shown, the graphene fiber prepared in this embodiment has a tensile strength of up to 504 MPa and an elongation at break of 9.1%.

[0069] Example 6

[0070] A method for preparing high-strength pure graphene fibers using Tesla valve microchannel assembly, the specific preparation method including the following steps:

[0071] (1) Take 3g of 200-mesh graphite powder to prepare graphite oxide by the modified Hummers method, then mechanically shear and peel it to make it into layers, centrifuge to separate it into graphene oxide slurry, and finally concentrate it to obtain an aqueous solution of graphene oxide with a concentration of 15mg / mL.

[0072] (2) Add 20 mL of DMF solvent to 5 mL of graphene oxide aqueous solution, stir evenly, centrifuge at 10000 rpm for 30 min, discard the supernatant, repeat the above steps 3 to 5 times, take out the lower layer solution and stir evenly to obtain a DFM solution of graphene oxide with a concentration of 15 mg / mL.

[0073] (3) The graphene oxide DMF spinning solution was injected into a coagulation bath solution of acetone and ethyl acetate through a Tesla valve microchannel with six valve channels to carry out microfluidic wet spinning at an injection speed of 0.3 mL / min to obtain graphene oxide fibers.

[0074] (4) Finally, the graphene oxide fibers obtained in step (3) are chemically reduced under the action of hydroiodic acid reducing agent. The reduction temperature is 60℃ and the reduction time is 4h to obtain graphene fibers. After mechanical property testing, such as... Figure 8 As shown, the graphene fiber prepared in this embodiment has a tensile strength of up to 1077 MPa and an elongation at break of 7.2%.

[0075] Comparative Example 1

[0076] (1) Take 3g of 200-mesh graphite powder to prepare graphite oxide by the modified Hummers method, then mechanically shear and peel it to make it into layers, centrifuge to separate it into graphene oxide slurry, and finally concentrate it to obtain an aqueous solution of graphene oxide with a concentration of 15mg / mL.

[0077] (2) Add 20 mL of DMF solvent to 5 mL of graphene oxide aqueous solution, stir evenly, centrifuge at 10000 rpm for 30 min, discard the supernatant, repeat the above steps 3 to 5 times, take out the lower layer solution and stir evenly to obtain a DFM solution of graphene oxide with a concentration of 15 mg / mL.

[0078] (3) The graphene oxide DMF spinning solution was injected into a coagulation bath of acetone and ethyl acetate mixture through a regular 23G (340μm inner diameter) circular spinning needle to carry out wet spinning at an injection speed of 0.3mL / min to obtain graphene oxide fibers.

[0079] (4) Finally, the graphene oxide fibers obtained in step (3) are chemically reduced under the action of hydroiodic acid reducing agent. The reduction temperature is 60℃ and the reduction time is 4h to obtain ordinary graphene fibers. Figure 9 As shown, from Figure 9 As can be seen, although the fibers prepared in this embodiment have good continuity, the fiber surface has abundant wrinkles, and the graphene sheets are relatively disordered. Mechanical property tests show that... Figure 10 As shown, the tensile strength of ordinary graphene fibers is only 264 MPa at most, and the elongation at break is 2.6%.

[0080] This invention provides a method for preparing high-strength pure graphene fibers using Tesla valve microchannels. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing high-strength pure graphene fibers using a Tesla valve microchannel, characterized in that, Includes the following steps: (1) Graphene oxide was prepared by the improved Hummers method, and after peeling, it was separated by centrifugation and concentrated to obtain an aqueous solution of graphene oxide; (2) Add DMF solvent to the graphene oxide aqueous solution in step (1), stir evenly and centrifuge to obtain DMF solution of graphene oxide; (3) Preparation of pure graphene oxide fibers: graphene oxide DMF solution was spun by microfluidic spinning using a Tesla valve microchannel to obtain graphene oxide fibers; (4) Preparation of pure graphene fiber: The graphene oxide fiber obtained in step (3) is subjected to a reduction reaction to obtain the pure graphene fiber. In step (3), the Tesla valve microchannel includes an inclined, continuously alternating, and obstructed curved pipeline; the total length L of the Tesla valve microchannel is 8~23 mm, the inlet width is 1~2 mm, the outlet width is 0.5~1 mm, and the channel depth is 1~3 mm.

2. The method for preparing high-strength pure graphene fibers using Tesla valve microchannels according to claim 1, characterized in that, In step (1), the concentration of the obtained graphene oxide aqueous solution is 10 mg / mL to 20 mg / mL.

3. The method for preparing high-strength pure graphene fibers using Tesla valve microchannels according to claim 1, characterized in that, In step (2), the centrifuge speed is 8000~10000 rpm, the centrifugation time is 0.5~1 hour, the centrifugation is repeated 3~5 times, and the supernatant is discarded after each centrifugation; the concentration of the obtained graphene oxide DMF solution is 10 mg / mL~20 mg / mL.

4. The method for preparing high-strength pure graphene fibers using Tesla valve microchannels according to claim 1, characterized in that, In step (3), the microfluidic wet spinning method is as follows: the DMF solution of the graphene oxide is injected into the coagulation bath solution through the Tesla valve microchannel spinning needle, and coagulated under the action of the coagulation bath to obtain the graphene oxide fiber.

5. The method for preparing high-strength pure graphene fibers using Tesla valve microchannels according to claim 4, characterized in that, In step (3), the injection pump is used to control the propulsion speed of the graphene oxide DMF solution in the Tesla valve microchannel to be 0.2~0.4 mL / min.

6. The method for preparing high-strength pure graphene fibers using Tesla valve microchannels according to claim 4, characterized in that, In step (3), the coagulation bath solution is a mixture of acetone and ethyl acetate in a volume ratio of 1:3~4. The graphene oxide fiber is soaked in the coagulation bath solution for 20~30 min and then taken out for stretching and drying.

7. The method for preparing high-strength pure graphene fibers using a Tesla valve microchannel according to claim 4, characterized in that, In step (4), the reducing agent used in the reduction reaction is any one of 40-60% hydroiodic acid aqueous solution, vitamin C aqueous solution or hydrazine hydrate aqueous solution, the temperature of the reduction reaction is 50-60 ℃, and the time is 4-8 hours.

8. High-strength pure graphene fibers prepared by the preparation method according to any one of claims 1 to 7.

9. The high-strength pure graphene fiber according to claim 8, characterized in that, The pure graphene fiber has a diameter of 30~80µm, the two-dimensional graphene sheets inside the fiber have a highly ordered orientation and regular arrangement structure, and the tensile strength of the pure graphene fiber is not less than 504 MPa and the elongation at break is not less than 6.8%.

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