Wear-resistant nanofiber-reinforced protective graphene fibers and their preparation methods and applications

Abstract

The present invention belongs to the technical field of functional composite fibers, and discloses a wear-resistant nanofiber-reinforced and protected graphene fiber, a preparation method thereof and an application. The wear-resistant nanofiber-reinforced and protected graphene fiber comprises a graphene fiber bundle and nanofibers. The nanofibers coat the graphene fiber bundle in the form of a three-dimensional porous network to form a stress buffer layer; wear-resistant particles are uniformly loaded inside the three-dimensional porous network. The preparation method is as follows: fixing the surface-pretreated graphene fiber on an electrospinning nanofiber yarn machine, forming a nanofiber membrane by electrospinning and uniformly wrapping it on the surface-pretreated graphene fiber, then winding it into a roll, and then performing a hot roll treatment on the wound fiber bundle to obtain the wear-resistant nanofiber-reinforced and protected graphene fiber. The application is: used for weaving to obtain a graphene fiber fabric. The fiber prepared by the present invention and the fabric woven therefrom have excellent mechanical properties, wear resistance, electrical conductivity and thermal conductivity at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional composite fibers, and relates to a wear-resistant nanofiber-reinforced protective graphene fiber, its preparation method and application. Background Art

[0002] In the field of preparing functional composite fiber materials, graphene fibers are gradually becoming the focus of research due to their unique electronic, thermal and mechanical properties. This two-dimensional structure material composed of single-layer carbon atoms has an extremely high specific surface area, excellent electrical and thermal conductivity, as well as high strength and high ductility. These properties endow graphene-based fibers with broad application potential in high-tech fields such as composite materials, sensors, flexible electronics, energy storage and conversion.

[0003] However, although graphene fibers have received extensive attention due to their excellent electrical conductivity and high specific strength, a series of challenges still exist in the process of converting them into practical engineering materials. First of all, although graphene fibers have high mechanical strength and good electrical conductivity, they are relatively brittle and are easily affected by friction or wear. Due to the rough surface and incomplete filling of pores of graphene fibers, this leads to insufficient wear resistance of the fibers, making it difficult for the fibers to be continuously woven into a shape.

[0004] The root cause of the above problems is that the graphene sheets are mainly bonded to each other through π-π stacking and van der Waals forces. This non-covalent interaction force is relatively weak and difficult to withstand large mechanical stresses. Therefore, under the action of tensile, bending or shear loads, the internal interlayer non-covalent bonds of graphene fibers are easily separated, increasing the risk of structural fracture. During the fiber-making and weaving processes, the sheets on the surface of the graphene fiber bundles are easily peeled off due to frictional or extrusion stresses, forming loose flying filaments or even breaking, seriously affecting the consistency and overall mechanical properties of the fiber bundles, and making it difficult for the fiber bundles to be woven into a shape.

[0005] In addition, there are large voids between the individual graphene fibers in the woven graphene fiber bundles. Even after twisting treatment, it is very difficult to completely remove these voids. These voids not only affect the transmission of electrons and phonons in the vertical direction, but also reduce the thermal conductivity and electrical conductivity of the material, thereby leading to a decrease in mechanical properties during application.

[0006] In order to improve this problem, although the existing sizing process can make the fiber bundles tightly bundled by coating, due to the rough surface of the individual graphene fibers, there are still voids between the single filaments after bundling. These voids still cannot be completely filled after sizing coating, resulting in the wear resistance of the fiber bundle surface being difficult to meet the weaving requirements. Therefore, it is necessary to explore other surface treatment technologies to enhance the wear resistance, mechanical properties (including strength, flexibility, modulus), electrical conductivity and thermal conductivity of the fiber bundles.

[0007] At present, although there are not many protective treatment technologies for graphene fibers, researchers are referring to the sizing technologies of fibers similar to graphene fibers (such as carbon fibers, basalt fibers, glass fibers, etc.) to explore methods to improve the surface characteristics of fiber tows. By introducing new treatment processes or reinforcing agents on the fiber surface, the processing performance of the fiber can be improved, and the interfacial bonding force between fiber tows can be increased, thereby enhancing the overall mechanical, electrical, and thermal conductivity properties of the fiber.

[0008] The patent with the authorization announcement number CN105254920B discloses a preparation method of a graphene paper prepreg. This method is to impregnate a graphene paper-like material in an epoxy resin solution to obtain a composite material. After the prepreg is cured, it retains the excellent electrical conductivity of graphene. However, the interfacial mismatch between graphene and epoxy resin will still cause interlayer separation of the composite material during high-stress deformation.

[0009] The patent application with the publication number CN118996562A discloses an anodic oxidation method for high-strength and medium-modulus polyacrylonitrile-based carbon fibers and carbon fibers. This method is to perform primary anodic oxidation treatment on the carbonized high-strength and medium-modulus polyacrylonitrile-based carbon fibers in an inorganic electrolyte, and then perform secondary anodic oxidation treatment in an organic electrolyte. In this way, on the basis of improving the interfacial properties of the high-strength and medium-modulus polyacrylonitrile-based carbon fibers, a significant reduction in the strength of the carbon fibers can be avoided. However, anodic oxidation mainly improves the interfacial properties and has limited contribution to surface wear resistance. The surface layer formed after oxidation is relatively fragile and is prone to wear or peeling under high-friction or impact conditions. Especially in secondary anodic oxidation (organic electrolyte environment), improper control may further damage the mechanical properties of the fiber.

[0010] In Reference 1 (Construction of cellulose nanofiber / carbon nanotube synergistic network on carbon fiber surface to enhance mechanical properties and thermal conductivity of composites[J].Composites Science and Technology, 2024, 3(22): 110454), a combination of polydopamine (PDA), cellulose nanofibers (CNF), polyvinyl alcohol (PVA), and amino-functionalized carbon nanotubes (CNT) was used to form a synergistic network on the surface of carbon fibers (CF) through hydrogen and covalent bonds. This strategy significantly enhanced the flexural strength, flexural modulus, interlaminar shear strength (ILSS), tensile strength, and interfacial shear strength (IFSS) of the resulting composites. However, the improvement in wear resistance of this structure is limited because the surface coating is soft, and the wear resistance of PVA and CNF is weak, making it difficult to effectively resist long-term friction and mechanical damage.

[0011] In Reference 2 (Growing Carbon Nanotubes In Situ Surrounding Carbon Fiber Surface via Chemical Vapor Deposition to Reinforce Flexural Strength of Carbon Fiber Composites[J].Polymers 2023, 15(10), 2309), vertically aligned carbon nanotubes (VACNT) were in-situ prepared on the surface of catalyst-treated CF via chemical vapor deposition (CVD) method, interwoven into a three-dimensional fiber network and completely surrounding the CF to form an integrated structure. It has great potential in manufacturing high-strength CFRP composites for aerospace applications. However, the main role of VACNT is to enhance the interfacial bonding performance and overall mechanical properties, while the carbon nanotubes themselves are relatively fragile and have weak wear resistance. They may easily fall off or be damaged, especially in a long-term high-friction environment; and the vertically aligned structure may lead to a decline in overall performance due to local fracture when worn.

[0012] Therefore, it is of great significance to study a wear-resistant nanofiber-reinforced protective graphene fiber and its preparation method and application to solve the above problems. Summary of the Invention

[0013] The object of the present invention is to solve the problems existing in the prior art and provide a wear-resistant nanofiber-reinforced protective graphene fiber, its preparation method and application.

[0014] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0015] A preparation method of a wear-resistant nanofiber-reinforced protective graphene fiber, fixing the surface-pretreated graphene fiber on an electrospinning nanofiber yarn machine (the electrospinning nanofiber yarn machine is prior art, and the specific fixing method of the surface-pretreated graphene fiber is: manually pulling out the end of the graphene fiber bundle on the spinning reel from the left conical wire guide, adjusting the tension of the pulled fiber bundle through a control device, and then leading the fiber bundle to the right guide hole and fixing it on the chuck of the wire collecting device, and controlling the winding speed of the fiber bundle by a motor drive system), forming a nanofiber membrane by electrospinning and uniformly wrapping it on the surface-pretreated graphene fiber, then winding it into a shaft, and then performing a hot pressing roller treatment on the wound fiber bundle to obtain the wear-resistant nanofiber-reinforced protective graphene fiber;

[0016] Performing a hot pressing roller treatment on the wound fiber bundle can remove the defects on the surface of the nanofiber membrane, cause the deformation and fusion of the surface nanofiber membrane, improve the surface smoothness, and reduce the surface non-uniformity; at the same time, it can reduce the voids between nanofibers, promote the diffusion and penetration of polymer chains on the graphene surface, make the combination of nanofibers and the graphene interface more stable, improve the density and strength of the fiber bundle, uniformly coat the fiber bundle, help improve the density and strength of the wear-resistant nanofiber-reinforced protective graphene fiber, and the heat can increase the fluidity of the polymer chain, making it better fill the microscopic uneven structure of graphene and increasing the actual contact area; at the same time, the heat treatment can relax the internal stress formed during the spinning process, reduce the probability of microcracks and interface peeling inside the material, and can also help remove the solvents that may not have been completely volatilized during the formation of the polymer nanofiber membrane, contributing to reducing the fragile interface caused by solvent residues between graphene and the nanofiber membrane;

[0017] The surface pretreatment adopts the method of plasma irradiation treatment. The active oxygen species (O + , O2 + , O3) in the plasma react with the carbon atoms on the graphene surface to generate oxygen-containing functional groups such as carboxyl (-COOH), hydroxyl (-OH), and epoxy group (C-O-C). The plasma irradiation treatment etches a small amount of active sites on the inert graphene fiber surface, making it easier to generate interface interactions with interface substances and anchor interface load materials;

[0018] The spinning solution used in electrospinning is obtained by adding wear-resistant particles to a polymer material solution; the wear-resistant particles are one or more of silicon dioxide (SiO2), aluminum oxide (Al2O3), zirconium oxide (ZrO), boron nitride nanotubes (BNNTs), graphene powder (GPs), and titanium carbide MXene (Ti2C3Tx), and the polymer material is polyurethane (PU), polyetherimide (PEI), poly(m-phenylene isophthalamide) (PMIA), poly(p-phenylene terephthalamide) (PPTA), polybenzimidazole (PBI), polyimide (PI), poly(p-phenylene benzobisoxazole) fiber (PBO), or poly(2,5-dihydroxy-1,4-phenylene pyridino bisimidazole) (PIPD).

[0019] As a preferred technical solution:

[0020] For the preparation method of the wear-resistant nanofiber-reinforced protective graphene fiber as described above, the plasma irradiation treatment uses an oxygen atmosphere, the pressure in the reaction chamber is 10 - 100 Pa, the oxygen flow rate is 20 - 100 sccm, the irradiation power is 50 - 200 W, and the treatment time is 30 - 300 s.

[0021] For the preparation method of the wear-resistant nanofiber-reinforced protective graphene fiber as described above, the mass ratio of the wear-resistant particles to the polymer material is 1:10 - 50, and the concentration of the polymer material solution is 1 - 20 wt%.

[0022] For the preparation method of the wear-resistant nanofiber-reinforced protective graphene fiber as described above, the electrospinning process parameters are: voltage 15 - 39 kV, the distance between the needle and the collector (i.e., the electrospinning nanofiber yarn machine) is 5 - 8 cm, the rate of the feeding pump is 0.5 - 2 mL / h, the winding rate of the fiber reel is 0.1 - 2 cm / min, the drying temperature is 50 - 80 °C, and the electrospinning time is 0.5 - 2 h.

[0023] For the preparation method of the wear-resistant nanofiber-reinforced protective graphene fiber as described above, the average diameter of the fibers in the nanofiber membrane is 50 - 1000 nm, and the thickness of the nanofiber membrane is 3 - 100 μm.

[0024] The preparation method of the wear-resistant nanofiber-reinforced protective graphene fiber as described above, the process parameters of the hot rolling treatment are: the roller temperature is 160 - 400 °C, and the roller temperature is set according to the characteristics of the material to be treated; the roller pressure is 5 - 20 MPa, and the roller pressure is set according to the type of fiber and the desired densification effect; the roller speed is 0.5 - 2 m / min; the roller gap is 80 - 200 μm. The roller gap refers to the minimum distance between two parallel hot rolling rollers (usually in micrometers μm) and can be adjusted according to the thickness of the composite fiber bundle. During the continuous treatment of the fiber, when the graphene fiber with a nanofiber coating passes through this gap, densification and interface strengthening are achieved under the action of hot rolling. After the hot rolling is completed, the roller temperature is gradually reduced and the pressure is appropriately reduced to avoid deformation or damage of the fiber bundle after hot rolling due to sudden temperature drop or excessive pressure.

[0025] The present invention also provides a wear-resistant nanofiber-reinforced protective graphene fiber prepared by the preparation method described in any one of the above. It includes a graphene fiber bundle and nanofibers. The nanofibers coat the graphene fiber bundle in the form of a three-dimensional porous network to form a stress buffer layer, which absorbs frictional energy through elastic deformation and reduces the specific wear rate of the surface. Wear-resistant particles are uniformly loaded inside the three-dimensional porous network to form a transfer film at the friction interface and dynamically reduce the friction coefficient. Through the multi-level structure design and interface optimization of the nanofiber reinforcement layer, a breakthrough improvement in the wear resistance of the graphene fiber bundle matrix is achieved, while retaining its intrinsic advantages of high conductivity and high strength.

[0026] As a preferred technical solution:

[0027] Compared with the graphene fiber without any treatment, for the wear-resistant nanofiber-reinforced protective graphene fiber as described above, the tensile strength is increased by 30 - 65%, the tensile elastic modulus is increased by 25 - 60%, the toughness is increased by 10 - 40%, the electrical conductivity is increased by 8 - 40%, the thermal conductivity is increased by 10 - 50%, the bending strength is increased by 35 - 65%, the bending modulus is increased by 40 - 75%, the bending curvature is increased by 10 - 25%, and the specific wear rate is reduced by 50 - 80%.

[0028] The present invention provides an application of the wear-resistant nanofiber-reinforced protective graphene fiber described in any one of the above, which is applied to the weaving to prepare a graphene fiber fabric.

[0029] As a preferred technical solution:

[0030] For the application of the wear-resistant nanofiber-reinforced protective graphene fiber as described above, the weaving methods are knitting, two-dimensional weaving, and three-dimensional weaving.

[0031] For the application of the wear-resistant nanofiber-reinforced protective graphene fiber as described above, compared with the control sample, the wear resistance life of the graphene fiber fabric is increased by 150 - 240%, the tensile strength is increased by 30 - 55%, the flexural fatigue life is increased by 80 - 180%, the electrical conductivity is increased by 5 - 20%, and the thermal conductivity is increased by 10 - 50%.

[0032] The preparation of the control sample is basically the same as that of the graphene fiber fabric described above, except that the fiber used for weaving is the graphene fiber after surface pretreatment, rather than the wear-resistant nanofiber-reinforced protective graphene fiber.

[0033] The graphene fiber tow after being coated with wear-resistant nanofibers has a relatively uniform surface structure and significantly improved wear resistance and mechanical properties. Therefore, it is suitable for the weaving process. The wear-resistant nanofiber-reinforced protective graphene fiber can provide excellent structural stability, enhanced mechanical strength and good flexibility during the weaving process, so as to meet complex weaving requirements, and can be woven into cloth by knitting, two-dimensional weaving or three-dimensional weaving techniques. The prepared graphene fiber fabric has excellent wear resistance and mechanical properties, and is suitable for military clothing, bulletproof armor and equipment for environments such as mechanical friction or chemical erosion.

[0034] The further application of such composite fibers can also be extended to the electronic and energy fields. In the electronics industry, based on the fabric of composite graphene fibers, due to its excellent electrical / thermal conductivity and wear resistance, it can be used as the core material of a new generation of flexible electronic devices, such as wearable electronics, flexible touch screens and smart textiles. In the energy field, these fabrics can be used as the electrodes of supercapacitors or the conductive backplanes of solar cells, and the high electrical conductivity and mechanical stability help to improve the performance of energy storage and conversion devices. In addition, the graphene fiber coated with a three-dimensional nanofiber structure has specific surface area and pore characteristics, and is expected to play an important role in catalysis, filtration and biomedical applications (such as artificial blood vessels and tissue engineering scaffolds). In the field of environmental science, the conductive composite fiber material will also play an application potential because it can be used for efficient filtration of particulate matter and harmful chemicals in the air.

[0035] Principle of the invention:

[0036] The structure of a silkworm cocoon is an optimized sample in nature. It is both strong and flexible, capable of effectively protecting the pupa, and the silk fibers on its outer layer also exhibit excellent mechanical properties in many applications. In this invention, we achieve the densification of nanofibers and the excellent mechanical, electrical, and thermal conductivity of fiber bundles by continuously coating fiber bundles with wear-resistant nanofibers and performing hot rolling. The fiber structure coated with nanofibers has a "strong outer layer - high-performance inner layer" structure similar to that of a silkworm cocoon. The nanofiber coating layer loaded with wear-resistant particles provides mechanical reinforcement and wear protection, while the core layer retains the high electrical and thermal conductivity characteristics of graphene fibers. Similar to the outer silk fiber structure of a silkworm cocoon, the nanofibers loaded with wear-resistant particles exhibit a high degree of uniformity and toughness, can resist external wear, provide enhanced protection performance for the fibers, make their surfaces more robust, and at the same time do not affect the performance of the internal fibers. The formed multi-level fiber structure can be applied to high-speed mechanical weaving. After being woven into cloth, it has excellent wear resistance, mechanical properties, and electrical and thermal conductivity, and is suitable for high-value-added fields such as military protection, aerospace, and intelligent textiles.

[0037] The principle of enhancing and protecting graphene fibers with a wear-resistant nanofiber layer and improving mechanical, electrical, thermal, and wear resistance properties in this invention is as follows:

[0038] (1)Mechanical property strengthening mechanism

[0039] There are a large number of rich wrinkles and grooves on the surface of single graphene fibers, which serve as mechanical anchoring points and can produce a "pinning effect" with the nanofiber coating layer. Moreover, after the graphene fibers are treated by plasma, oxygen-containing functional groups (-COOH, -OH) are generated on the surface, forming hydrogen bonds and covalent bonds with polar groups (such as amino groups, amide groups) of nanofibers such as polyimide (PI) and poly(p-phenyleneterephthalamide) (PPTA), resulting in a significant increase in tensile strength.

[0040] Based on the nanofiber bridging effect, nanofibers form a high-density interpenetrating network on the surface of graphene (network density > 10 9 / m², the network density refers to the interweaving density of fibers in the nanofiber network, that is, the number of fiber interweaving points per unit area. By obtaining a high-resolution image of the nanofiber membrane through a scanning electron microscope (SEM), processing the image with image analysis software, extracting the number of fiber interweaving points, and measuring its density, the network density can be obtained), and dispersing external loads through mechanical interlocking. For example, when the fiber is stretched, the nanofiber network bridges both sides of the crack, disperses the local stress to a larger range, inhibits the crack propagation on the graphene fiber, and greatly improves the tensile strength.

[0041] In addition, a flexible nanofiber membrane wraps around high-modulus graphene fibers to form a "rigid-flexible combination" structure with a modulus gradient. The flexible layer is used to absorb impact energy (such as crack propagation energy), while the rigid layer bears the main load. The soft and hard layers cooperate to enhance the toughness of the composite material (the toughness is increased by 2 to 3 times).

[0042] (2)Optimization mechanism of electrical / thermal conductivity

[0043] After the nanofiber membrane wraps around the graphene fibers, through the action of hot rolling, the graphene fibers are closely arranged, significantly increasing the contact area between the fibers (the contact point density is increased by 50 - 100%); at the same time, the close contact reduces the air gaps and interfacial defects between the graphene fibers, lowering the electron transition barrier between the fibers and forming a low-resistance conductive path. In addition, after densification, the van der Waals interaction between the graphene fibers is enhanced, forming a continuous conductive network throughout the composite material, and the electrical conductivity is increased by 10 - 40%.

[0044] (3)Optimization mechanism of wear resistance

[0045] Firstly, there is the protective effect of the nanofiber membrane. A layer of wear-resistant nanofibers is coated on the surface of the graphene fibers, and the densification of the nanofibers is achieved through hot rolling technology. This layer of nanofiber coating has good hardness and anti-friction properties, effectively reducing the frictional contact between the fiber surface and external objects and improving the wear resistance of the fabric. The dense structure of the coating fills the gaps between the fibers, further enhancing the stability of the fiber bundle and reducing surface damage caused by friction; at the same time, the high-density intertwined nanofibers formed by electrospinning technology strengthen the mutual connection between the graphene fibers, making the surface of the fiber bundle more firm, reducing the friction between single fibers, and lowering the probability of breakage during the friction process; the wear-resistant particles distributed on the surface of the nanofibers have good anti-wear performance, which can further strengthen the fiber surface and significantly enhance its resistance to external wear forces.

[0046] Beneficial effects:

[0047] (1)In the present invention, the wear-resistant nanofibers continuously coat the fiber bundles and hot rolling is carried out to achieve the densification of the nanofibers as well as the excellent mechanical properties and electrical / thermal conductivity of the fiber bundles. At the same time, the fiber structure coated with nanofibers has a "strong outer layer - high-performance inner layer" structure similar to a silkworm cocoon. The nanofiber coating layer loaded with wear-resistant particles provides mechanical enhancement and wear protection, and the core layer retains the high electrical / thermal conductivity characteristics of the graphene fibers.

[0048] (2)In the present invention, the wrinkles and grooves on the surface of the single graphene fiber generate a "pinning effect" with the nanofiber coating layer, and then hydrogen bonds and covalent bonds are formed between the oxygen-containing functional groups generated on the surface of the graphene fiber and the polar groups of the nanofibers, resulting in a significant increase in the tensile strength.

[0049] (3) Through the action of hot roll pressing, the graphene fibers in the present invention are closely arranged, significantly increasing the contact area between the fibers, reducing the air gaps and interfacial defects between the graphene fibers, lowering the transition barrier of electrons between the fibers, forming a low-resistance conductive path, and thus improving the electrical conductivity.

[0050] (4) After coating a layer of wear-resistant nanofibers on the surface of the graphene fibers and through hot roll pressing treatment in the present invention, the nanofiber coating layer has good hardness and anti-friction performance, effectively reducing the frictional contact between the fiber surface and external objects, improving the wear resistance of the fabric, and the wear-resistant particles distributed on the surface of the nanofibers have good anti-wear performance, which can further strengthen the fiber surface and significantly enhance its resistance to external wear forces. Description of the Drawings

[0051] Figure 1 is a schematic diagram of the working process of the nanofiber spinning machine of the present invention;

[0052] Figure 2 is a SEM image of the nanofiber membrane of wear-resistant nanofiber-reinforced and protected graphene fibers prepared in Example 1 of the present invention;

[0053] Figure 3 is a schematic diagram of the wear-resistant nanofiber-reinforced and protected graphene fibers prepared in Example 1 of the present invention;

[0054] In the figure, 1 - wire outlet shaft, 2 - graphene fiber bundle after surface pretreatment, 3 - motor I, 4 - conical wire guide, 5 - spinneret, 6 - graphene fiber bundle wrapped with nanofiber membrane, 7 - guiding hole, 8 - wire take-up shaft, 9 - motor II. Detailed Embodiments

[0055] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0056] To ensure the full disclosure of the performance of the substances used in each embodiment and comparative example, the manufacturers and grades of the substances are specified. Products of other manufacturers and grades that meet the limitations of the present invention are also feasible.

[0057] The test methods for the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0058] Tensile strength, tensile elastic modulus, and toughness of the fiber: The wear-resistant nanofiber-reinforced and protected graphene fibers prepared in each example were used as samples, and then the tensile strength of the samples was tested with reference to the standard of GB / T 3362-2017 "Test Method for Tensile Properties of Carbon Fiber Multifilaments". , tensile elastic modulus E, and elongation at break (the adhesive used during the test was prepared according to A.3.3 in this standard). Then, based on the integral stress-strain curve (the area under the stress-strain curve) obtained during the test, the toughness was calculated through its calculation formula. The calculation formula for toughness is: U = , where is the strain, is the stress.

[0059] Electrical conductivity of the fiber: The wear-resistant nanofiber-reinforced and protected graphene fibers prepared in each example were used as samples. Then, the samples were laid flat on an insulating PET film and fixed at both ends with conductive double-sided tape to ensure that the contact section of the samples with the four probes was straight and without bending. In the fiber test mode of the four-probe conductivity tester, the probes were pressed down to the surface of the samples. After applying a current of 10 μA through the four-probe conductivity tester, the voltage value V was read. The resistance value R = V / I. Then, the conductivity of the samples was calculated based on the measured data. The calculation formula is: Conductivity = , where l is the probe spacing (1.59 mm) and d is the diameter of the sample.

[0060] Thermal conductivity of the fiber: The wear-resistant nanofiber-reinforced and protected graphene fibers prepared in each example were used as samples, and then the thermal conductivity of the samples was tested with reference to the standard of Q / 110000 BH 008-2018.

[0061] Specific wear rate of the fiber: The wear-resistant nanofiber-reinforced and protected graphene fibers prepared in each example were used as samples. Subsequently, the wear resistance of the samples was tested on a reciprocating wear testing machine. Then, the weight ΔW (in grams (g)) lost by the samples after the test was obtained by comparing the weights of the samples before and after the test. The specific wear rate (in mm 3 / (N·m)) to evaluate the wear resistance of the sample. The calculation formula for the specific wear rate is: specific wear rate = (ΔW × 1000) / (ρ × L × F). In the formula, L is the total sliding distance during the wear process (unit: meter (m)), F is the normal force applied to the sample (unit: Newton (N)), and ρ is the density of the sample. Among them, the conditions for testing wear resistance are: the friction pair is an Al2O3 ceramic disc (Ra = 0.8 μm, diameter = 30 mm), the reciprocating frequency is 5 Hz, the stroke is 10 mm, the test temperature is 23 °C, the humidity is 50%, the total sliding distance during the wear process is 500 m, and the normal force applied to the sample is 1.0 N. The density of the sample is measured by referring to Method C in the GB / T30019-2013 standard, and the unit is g / cm 3 .

[0062] Flexural strength, flexural modulus and flexural curvature of the fiber: Take the wear-resistant nanofiber-reinforced protective graphene fiber prepared in each example as the sample. Then, first wrap a 500-mm sample around a multifilament holder according to the GB / T 3362—2017 standard, and then immerse it in a resin sizing solution at 25 °C (prepared according to A.3.3 in the GB / T 3362—2017 standard) and let it stand for 5 min. Place it in a 120 °C electrothermal blast drying oven. After curing, obtain a carbon fiber composite sample bar. Then, refer to the GB / T 1449-2005 "Test Method for Flexural Properties of Fiber Reinforced Plastics" standard to test the flexural strength and flexural modulus of the carbon fiber composite sample bar. In the three-point bending test, through a laser displacement sensor (Keyence LK-G5000, accuracy ±0.5 μm), synchronously record the load-displacement curve to obtain the maximum displacement δ (unit: mm) at the peak point of the curve. Then, first derive the radius of curvature r through geometric relations ( , where is the span of the sample bar), and then obtain the flexural curvature according to the calculation formula . The calculation formula for its flexural curvature is: .

[0063] Tensile strength of the fabric: Take the graphene fiber fabric and the comparative sample prepared in each example as samples respectively. Then, refer to the ASTM D5035-11(2024) "Breaking Strength and Elongation of Textile Fabrics (Strip Method)" standard to test the samples to obtain the maximum breaking strength (N). Then, calculate the tensile strength (MPa) according to the obtained data. The calculation formula is: tensile strength = maximum breaking strength (N) / (effective width of the sample × fabric thickness). Among them, the effective width refers to the clamping width, and the unit of fabric thickness is mm 2 .

[0064] Electrical conductivity of the fabric: The graphene fiber fabrics prepared in each example and the comparative samples were respectively cut into pieces of 20 mm × 20 mm, and then the cut fabrics were used as samples for testing. The specific process was as follows: First, the sample was laid flat on the test bench and the edges were fixed with a transparent pressing plate (to prevent wrinkling). Then, in the fabric test mode of the four-probe electrical conductivity tester, the probes contacted the surface of the sample with a pressure of 50 mN, and after applying a current of 10 mA through the four-probe electrical conductivity tester, the surface resistance (unit: Ω / sq) was obtained. Then, the electrical conductivity of the sample (unit: S / m) was calculated according to the measured data. The calculation formula was: Electrical conductivity = , where t is the thickness of the sample.

[0065] Thermal conductivity of the fabric: The graphene fiber fabrics prepared in each example and the comparative samples were respectively used as samples, and then the samples were tested with reference to the standard of GB / T 8722-2019 "Determination method for thermal conductivity of carbon materials". Based on the flash method, the thermal diffusivity α (unit: m 2 / s) of the fabric was measured. Then, the specific heat capacity c p (unit: J / (kg·K)) of the sample was measured by DSC. The density of the sample was measured using GB / T 4668-1995 "Determination of the density of woven fabrics". Then, the thermal conductivity λ (unit: W / (m·K)) was obtained through the calculation formula according to the measured data. The calculation formula was: , where ρ is the density.

[0066] Abrasion resistance life: The graphene fiber fabrics prepared in each example and the comparative samples were respectively used as samples, and then the samples were tested with reference to the standard of ISO 12947-2:2016 "Textiles—Determination of the abrasion resistance of fabrics by the Martindale method". On the Martindale tester, alumina film (Ra ≤ 0.1 μm) abrasive was selected, and under the stress condition of 9 kPa, Lissajous trajectory friction was used to simulate multi-directional friction. The test was stopped when the single filament breakage ≥ 10% (statistically counted in 5 random microscopic areas). The abrasion resistance life was the number of friction cycles at the termination.

[0067] Flexural fatigue life: The graphene fiber fabrics prepared in each example and the comparative samples were respectively cut into standard sizes of 25 mm × 50 mm and used as samples for testing with a dynamic mechanical analyzer. The specific process was as follows: In the three-point bending mode, first, the sample was horizontally placed between two fixed support points (span L= 40 mm), and then the maximum allowable bending angle of the sample was determined through preliminary experiments. The cyclic bending angle was determined to be 10°, and then the three-point bending stress was calculated. Then, the displacement control mode was selected, and a vertical downward periodic load was applied through a movable loading head at the center of two fixed support points (i.e., the loading head moved up and down in the form of a sine wave with a frequency of 1 Hz). During the start of the test, the load-displacement curve was monitored in real time until the load dropped to the fracture of the sample, and at the same time, the number of cycles of the sample from the initial loading to complete fracture was recorded, which was the bending fatigue life. Among them, the determination of the maximum allowable bending angle was as follows: The sample was subjected to quasi-static bending until fracture to obtain δmax, and δcyclic = 0.5×δmax was set, which was converted to a bending angle θ = 10°. The calculation formula for the three-point bending stress was: Three-point bending stress = 3 FL / 2 bh 2 , where F is the loading load (N), which is given by the test software in real time, L is the span, b is the width of the sample (i.e., 25 mm), h is the thickness of the sample (in μm).

[0068] Example 1

[0069] A preparation method of wear-resistant nanofiber-reinforced protective graphene fibers, the steps are as follows:

[0070] (1) Preparation of raw materials;

[0071] Wear-resistant particles: silica, with a particle size of 50 - 80 nm;

[0072] Polymer material: polyurethane, manufactured by Covestro Polymer (China) Co., Ltd., with the brand name Desmocomp® 385 S;

[0073] Graphene fiber tow: First, a GO (graphene oxide, with a lateral size of 10 - 50 μm and a thickness of 1 - 5 nm) / DMF (N,N-dimethylformamide) solution with a concentration of 10 mg / g was wet-spun (the coagulation bath was ethyl acetate) to obtain a graphene oxide fiber tow, and then it was soaked in a hydroiodic acid / ethanol solution (the volume ratio of hydroiodic acid to ethanol was 1:3) and chemically reduced at 60 °C to obtain a chemically reduced graphene fiber tow, and then it was thermally drawn at 1200 °C to obtain a graphene fiber tow;

[0074] The number of single graphene fibers in the obtained graphene fiber tow was 20, the diameter of the graphene fiber tow was 0.12 mm, the tensile strength was 950 MPa, the tensile elastic modulus was 100 GPa, and the toughness was 30 MJ / m 3, with a conductivity of 1500 S / cm, a thermal conductivity of 300 W / m·K, a flexural strength of 800 MPa, a flexural modulus of 800 MPa, a flexural curvature of 2%, and a specific wear rate of 0.08 mm 3 / (N·m);

[0075] Ethanol: with a purity of 99%;

[0076] The solvent in the polymer material solution: N,N-dimethylformamide and tetrahydrofuran with a volume ratio of 3:1;

[0077] (2) Prepare the spinning solution;

[0078] First, add the polymer material to the solvent and completely dissolve the polymer material, then use a magnetic stirrer to stir at 60 °C for 6 hours until the solution is completely homogeneous to obtain a polymer material solution with a concentration of 1 wt%. Then, add the wear-resistant particles to the polymer material solution and sonicate at a power of 200 W for 1 h, and then continue to stir until the wear-resistant particles are uniformly dispersed in the polymer material solution. Finally, filter the polymer material solution through a filter membrane with a pore size of 0.45 μm to obtain the spinning solution; among them, the mass ratio of the wear-resistant particles to the polymer material is 1:10;

[0079] (3) First, soak and clean the graphene fiber bundle in ethanol for 10 min, then take it out and dry it at 40 °C for 6 h, and then perform plasma irradiation treatment on the dried graphene fiber bundle in an oxygen atmosphere; among them, the pressure in the reaction chamber is 10 Pa, the oxygen flow rate is 20 sccm, the irradiation power is 50 W, and the treatment time is 30 s;

[0080] (4) As Figure 1 shown, place the surface-pretreated graphene fiber bundle 2 on the wire outlet shaft 1. After starting the conical wire guide 4 and the take-up shaft 8 through the motor I 3 and the motor II 9, the surface-pretreated graphene fiber bundle 2 will pass through the conical wire guide 4, and then use electrospinning to spray the spinning solution prepared in step (2) through the spinneret 5 to form a nanofiber membrane and uniformly wrap it on the surface-pretreated graphene fiber bundle 2 to obtain a graphene fiber bundle 6 wrapped with a nanofiber membrane. After passing through the guide hole 7, it is wound into a shaft by the take-up shaft 8; among them, the average diameter of the fibers in the nanofiber membrane is 50 nm, and the thickness of the nanofiber membrane is 10 μm;

[0081] The spinning process parameters are: voltage 15 kV, distance between the needle and the collector 5 cm, propelling pump rate 0.5 mL / h, fiber reel take-up rate 0.1 cm / min, drying temperature 50 °C, and spinning time 0.5 h;

[0082] (5) Perform hot-roll treatment on the fiber bundle after winding in step (4) to obtain wear-resistant nanofiber-reinforced protective graphene fibers;

[0083] The process parameters of the hot-roll treatment are as follows: roller temperature 160 °C, roller pressure 5 MPa, roller speed 0.5 m / min, and roller gap 80 μm.

[0084] The finally obtained wear-resistant nanofiber-reinforced protective graphene fibers (the electron microscope image of its nanofiber membrane is as shown in Figure 2 shown) are composed of graphene fiber bundles and nanofibers. As shown in Figure 3 shown, the nanofibers coat the graphene fiber bundles in the form of a three-dimensional porous network, forming a stress buffer layer with a thickness of 3 μm; wear-resistant particles are uniformly loaded inside the three-dimensional porous network;

[0085] Compared with the untreated graphene fiber bundles, the tensile strength of the wear-resistant nanofiber-reinforced protective graphene fibers is increased by 40%, the tensile elastic modulus is increased by 40%, the toughness is increased by 35%, the electrical conductivity is increased by 8%, the thermal conductivity is increased by 10%, the bending strength is increased by 40%, the bending modulus is increased by 45%, the bending curvature is increased by 12%, and the specific wear rate is reduced by 60%.

[0086] The application of the wear-resistant nanofiber-reinforced protective graphene fibers is as follows: The above-prepared wear-resistant nanofiber-reinforced protective graphene fibers are knitted to obtain a graphene fiber fabric; among them, the number of needles (i.e., the needle density) during the knitting process is 8 needles per inch;

[0087] The thickness of the obtained graphene fiber fabric is 0.29 mm, the wear-resistant life is 8×10 3 times, the tensile strength is 360 MPa, the bending fatigue life is 3×10 3 times, the electrical conductivity is 250 S / cm, and the thermal conductivity is 90 W / (m·K);

[0088] Replace the wear-resistant nanofiber-reinforced protective graphene fibers with the graphene fiber bundles in step (1) above, and prepare a comparison sample according to the same process as the graphene fiber fabric. Compared with the comparison sample, the wear-resistant life of the graphene fiber fabric is increased by 150%, the tensile strength is increased by 30%, the bending fatigue life is increased by 80%, the electrical conductivity is increased by 8%, and the thermal conductivity is increased by 10%.

[0089] Example 2

[0090] The preparation method of the wear-resistant nanofiber-reinforced protective graphene fibers is as follows:

[0091] (1) Preparation of raw materials;

[0092] Wear-resistant particles: alumina, with a particle size of 150 - 200 nm;

[0093] Polymer material: polyetherimide, manufactured by Suzhou Jutai New Materials Co., Ltd., grade JTYPEI ® NA;

[0094] Graphene fiber bundle: First, a GO (graphene oxide, with a lateral size of 10 - 50 μm and a thickness of 1 - 5 nm) / DMF solution with a concentration of 10 mg / g is wet-spun (the coagulation bath is ethyl acetate) to obtain a graphene oxide fiber bundle. Then, it is soaked in a hydroiodic acid / ethanol solution (the volume ratio of hydroiodic acid to ethanol is 1:3) and chemically reduced at 60 °C to obtain a chemically reduced graphene fiber bundle. Finally, it is thermally stretched at 1200 °C to obtain a graphene fiber bundle;

[0095] The number of single graphene fibers in the prepared graphene fiber bundle is 50. The diameter of the graphene fiber bundle is 0.38 mm, the tensile strength is 850 MPa, the tensile elastic modulus is 90 GPa, and the toughness is 25 MJ / m 3 , the electrical conductivity is 1200 S / cm, the thermal conductivity is 250 W / m·K, the flexural strength is 700 MPa, the flexural modulus is 70 GPa, the flexural curvature is 1.80%, and the specific wear rate is 0.1 mm 3 / (N·m);

[0096] Ethanol: purity 99%;

[0097] Solvent in the polymer material solution: N-methylpyrrolidone and dimethylsulfinamide with a volume ratio of 1:1;

[0098] (2) Prepare the spinning solution;

[0099] First, add the polymer material to the solvent and completely dissolve the polymer material. Then, use a magnetic stirrer to stir at 90 °C for 4 hours until the solution is completely homogeneous to obtain a polymer material solution with a concentration of 3 wt%. Then, add wear-resistant particles to the polymer material solution and sonicate at a power of 300 W for 1 h, and then continue to stir until the wear-resistant particles are evenly dispersed in the polymer material solution. Finally, filter the polymer material solution through a filter membrane with a pore size of 0.22 μm to obtain the spinning solution; among them, the mass ratio of the wear-resistant particles to the polymer material is 1:15;

[0100] (3) First, soak the graphene fiber bundle in ethanol for 20 min, then take it out and dry it at 45 °C for 8 h. Then, perform plasma irradiation treatment on the dried graphene fiber bundle in an oxygen atmosphere; among them, the pressure in the reaction chamber is 60 Pa, the oxygen flow rate is 40 sccm, the irradiation power is 120 W, and the treatment time is 190 s;

[0101] (4) Fix the surface-pretreated graphene fiber bundle on an electrospinning nanofiber yarn machine, and then use the spinning solution prepared in step (2) to form a nanofiber membrane by electrospinning and uniformly wrap it on the surface-pretreated graphene fiber bundle, and then wind it into a roll; wherein, the average diameter of the fibers in the nanofiber membrane is 150 nm, and the thickness of the nanofiber membrane is 15 μm;

[0102] The spinning process parameters are: voltage 25 kV, distance between the needle and the collector 7 cm, propelling pump rate 1.5 mL / h, fiber reel winding rate 1 cm / min, drying temperature 55 °C, spinning time 1 h;

[0103] (5) Perform hot roll treatment on the fiber bundle wound in step (4) to obtain wear-resistant nanofiber-reinforced protective graphene fibers;

[0104] The process parameters of the hot roll treatment are: roll temperature 230 °C, roll pressure 13 MPa, roll speed 1.2 m / min, roll gap 105 μm.

[0105] The finally obtained wear-resistant nanofiber-reinforced protective graphene fibers are composed of graphene fiber bundles and nanofibers. The nanofibers coat the graphene fiber bundles in the form of a three-dimensional porous network, forming a stress buffer layer with a thickness of 7 μm; wear-resistant particles are uniformly loaded inside the three-dimensional porous network;

[0106] Compared with the untreated graphene fiber bundles, the tensile strength of the wear-resistant nanofiber-reinforced protective graphene fibers is increased by 50%, the tensile elastic modulus is increased by 45%, the toughness is increased by 25%, the electrical conductivity is increased by 15%, the thermal conductivity is increased by 15%, the bending strength is increased by 45%, the bending modulus is increased by 50%, the bending curvature is increased by 15%, and the specific wear rate is reduced by 65%.

[0107] The application of the wear-resistant nanofiber-reinforced protective graphene fibers is as follows. Specifically, the above-prepared wear-resistant nanofiber-reinforced protective graphene fibers are knitted to obtain a graphene fiber fabric; wherein, the number of needles during the knitting process is 15 needles per inch;

[0108] The thickness of the obtained graphene fiber fabric is 0.91 mm, the wear-resistant life is 2×10^4 times, the tensile strength is 580 MPa, the bending fatigue life is 8×10 3 times, the electrical conductivity is 350 S / cm, and the thermal conductivity is 130 W / (m·K);

[0109] Replace the wear-resistant nanofiber-reinforced protective graphene fiber with the graphene fiber tow in the above step (1), and prepare a comparative sample according to the same process as the graphene fiber fabric. Compared with the comparative sample, the wear resistance life of the graphene fiber fabric is increased by 180%, the tensile strength is increased by 45%, the flexural fatigue life is increased by 140%, the electrical conductivity is increased by 15%, and the thermal conductivity is increased by 12%.

[0110] Example 3

[0111] The preparation method of the wear-resistant nanofiber-reinforced protective graphene fiber is as follows:

[0112] (1)Preparation of raw materials;

[0113] Wear-resistant particles: zirconia, with a particle size of 80 - 100 nm;

[0114] Polymer material: poly(m-phenylene isophthalamide), manufactured by Chaomeisi New Materials Co., Ltd., with the brand name X-FIPER Chaomeisi aramid fiber;

[0115] Graphene fiber tow: First, a GO (graphene oxide, with a lateral size of 10 - 50 μm and a thickness of 1 - 5 nm) / DMF solution with a concentration of 10 mg / g is wet-spun (the coagulation bath is ethyl acetate) to obtain a graphene oxide fiber tow, then it is soaked in a hydroiodic acid / ethanol solution (the volume ratio of hydroiodic acid to ethanol is 1:3) and chemically reduced at 60 °C to obtain a chemically reduced graphene fiber tow, and then thermally stretched at 1200 °C to obtain a graphene fiber tow;

[0116] The number of single filaments of graphene fiber in the obtained graphene fiber tow is 100, the diameter of the graphene fiber tow is 0.45 mm, the tensile strength is 800 MPa, the tensile elastic modulus is 80 GPa, and the toughness is 20 MJ / m 3 , the electrical conductivity is 1000 S / cm, the thermal conductivity is 200 W / m·K, the flexural strength is 600 MPa, the flexural modulus is 60 GPa, the flexural curvature is 1.50%, and the specific wear rate is 0.12 mm 3 / (N·m);

[0117] Ethanol: with a purity of 99%;

[0118] Solvent in the polymer material solution: N-methylpyrrolidone and dimethyl sulfoxide with a volume ratio of 1:1;

[0119] (2)Prepare the spinning solution;

[0120] First, add the polymer material to the solvent and completely dissolve the polymer material. Then, use a magnetic stirrer to stir at 105 °C for 5 hours until the solution is completely homogeneous to obtain a polymer material solution with a concentration of 5 wt%. Next, add the wear-resistant particles to the polymer material solution and ultrasonicate at a power of 350 W for 0.5 h, and then continue stirring until the wear-resistant particles are uniformly dispersed in the polymer material solution. Finally, filter the polymer material solution with a PTFE filter membrane with a pore size of 0.45 μm to obtain a spinning solution; wherein, the mass ratio of the wear-resistant particles to the polymer material is 1:20;

[0121] (3)First, soak and clean the graphene fiber bundle in ethanol for 30 min, then take it out and dry it at 50 °C for 10 h, and then perform plasma irradiation treatment on the dried graphene fiber bundle in an oxygen atmosphere; wherein, the pressure in the reaction chamber is 100 Pa, the oxygen flow rate is 100 sccm, the irradiation power is 200 W, and the treatment time is 300 s;

[0122] (4)Fix the surface-pretreated graphene fiber bundle on an electrospinning nanofiber yarn machine, and then use the spinning solution prepared in step (2) to form a nanofiber membrane by electrospinning and uniformly wrap it on the surface-pretreated graphene fiber bundle, and then wind it into a roll; wherein, the average diameter of the fibers in the nanofiber membrane is 250 nm, and the thickness of the nanofiber membrane is 40 μm;

[0123] The spinning process parameters are: voltage 39 kV, distance between the needle and the collector 8 cm, propelling pump rate 2 mL / h, fiber reel winding rate 2 cm / min, drying temperature 60 °C, spinning time 2 h;

[0124] (5)Perform hot roll treatment on the fiber bundle wound in step (4) to obtain wear-resistant nanofiber-reinforced protective graphene fibers;

[0125] The process parameters of the hot roll treatment are: roll temperature 400 °C, roll pressure 20 MPa, roll speed 2 m / min, roll gap 200 μm.

[0126] The finally obtained wear-resistant nanofiber-reinforced protective graphene fibers are composed of graphene fiber bundles and nanofibers. The nanofibers coat the graphene fiber bundles in the form of a three-dimensional porous network to form a stress buffer layer with a thickness of 20 μm; wear-resistant particles are uniformly loaded inside the three-dimensional porous network;

[0127] Compared with the untreated graphene fiber bundle, the tensile strength of the wear-resistant nanofiber-reinforced protective graphene fibers is increased by 50%, the tensile elastic modulus is increased by 50%, the toughness is increased by 25%, the electrical conductivity is increased by 20%, the thermal conductivity is increased by 20%, the bending strength is increased by 55%, the bending modulus is increased by 60%, the bending curvature is increased by 20%, and the specific wear rate is reduced by 70%.

[0128] Application of wear-resistant nanofiber-reinforced protective graphene fibers. The specific process is as follows: The prepared wear-resistant nanofiber-reinforced protective graphene fibers are woven by a two-dimensional weaving method to obtain a graphene fiber fabric. Among them, during the weaving process, the warp density is 20 threads / cm and the weft density is 35 threads / cm.

[0129] The thickness of the obtained graphene fiber fabric is 1.08 mm, the wear-resistant life is 4×10⁴ times, the tensile strength is 700 MPa, the flexural fatigue life is 2×10 4 times, the electrical conductivity is 1000 S / cm, and the thermal conductivity is 200 W / (m·K).

[0130] Replace the wear-resistant nanofiber-reinforced protective graphene fibers with the graphene fiber tow in step (1) above, and prepare a comparative sample according to the same process as the graphene fiber fabric. Compared with the comparative sample, the wear-resistant life of the graphene fiber fabric is increased by 200%, the tensile strength is increased by 45%, the flexural fatigue life is increased by 160%, the electrical conductivity is increased by 15%, and the thermal conductivity is increased by 20%.

[0131] Example 4

[0132] Preparation method of wear-resistant nanofiber-reinforced protective graphene fibers. The steps are as follows:

[0133] (1) Preparation of raw materials;

[0134] Wear-resistant particles: Boron nitride nanotubes, with an average diameter of 20 nm and an average length of 1 μm;

[0135] Polymer material: Poly(p-phenylene terephthalamide), manufactured by Taher New Material Group Co., Ltd., with the brand name Taipulong® pulp;

[0136] Graphene fiber tow: First, a GO (graphene oxide, with a lateral size of 10 - 50 μm and a thickness of 1 - 5 nm) / DMF solution with a concentration of 10 mg / g is wet-spun (the coagulation bath is ethyl acetate) to obtain a graphene oxide fiber tow, and then it is soaked in a hydroiodic acid / ethanol solution (the volume ratio of hydroiodic acid to ethanol is 1:3) at 60 °C for chemical reduction to obtain a chemically reduced graphene fiber tow, and then it is thermally drawn at 1200 °C to obtain a graphene fiber tow;

[0137] The number of single graphene fibers in the obtained graphene fiber tow is 500, the diameter of the graphene fiber tow is 0.85 mm, the tensile strength is 700 MPa, the tensile elastic modulus is 70 GPa, and the toughness is 18 MJ / m 3, with a conductivity of 800 S / cm, a thermal conductivity of 180 W / m·K, a flexural strength of 500 MPa, a flexural modulus of 50 GPa, a flexural curvature of 1.20%, and a specific wear rate of 0.15 mm 3 / (N·m);

[0138] Ethanol: with a purity of 99%;

[0139] Solvent in the polymer material solution: N-methylpyrrolidone and dimethylsulfinamide with a volume ratio of 1:1;

[0140] (2) Prepare the spinning solution;

[0141] First, add the polymer material to the solvent and completely dissolve the polymer material, then use a magnetic stirrer to stir at 120 °C for 6 hours until the solution is completely uniform to obtain a polymer material solution with a concentration of 8 wt%. Then, add the wear-resistant particles to the polymer material solution and ultrasonicate at a power of 450 W for 1 h, and then continue to stir until the wear-resistant particles are uniformly dispersed in the polymer material solution. Finally, filter the polymer material solution through a PTFE filter membrane with a pore size of 1.0 μm to obtain the spinning solution; among them, the mass ratio of the wear-resistant particles to the polymer material is 1:25;

[0142] (3) First, soak and clean the graphene fiber bundle in ethanol for 10 min, then take it out and dry it at 55 °C for 12 h, and then perform plasma irradiation treatment on the dried graphene fiber bundle in an oxygen atmosphere; among them, the pressure in the reaction chamber is 10 Pa, the oxygen flow rate is 20 sccm, the irradiation power is 50 W, and the treatment time is 50 s;

[0143] (4) Fix the surface-pretreated graphene fiber bundle on an electrospinning nanofiber yarn machine, and then use the spinning solution prepared in step (2) to form a nanofiber membrane by electrospinning and uniformly wrap it on the surface-pretreated graphene fiber bundle, and then wind it into a roll; among them, the average diameter of the fibers in the nanofiber membrane is 225 nm, and the thickness of the nanofiber membrane is 30 μm;

[0144] The spinning process parameters are: voltage 15 kV, distance between the needle and the collector 5 cm, propelling pump rate 0.5 mL / h, fiber reel winding rate 0.5 cm / min, drying temperature 65 °C, spinning time 0.5 h;

[0145] (5) Perform hot roll treatment on the fiber bundle wound in step (4) to obtain wear-resistant nanofiber-reinforced protective graphene fiber;

[0146] The process parameters of the hot roll treatment are: roll temperature 200 °C, roll pressure 8 MPa, roll speed 0.8 m / min, roll gap 100 μm.

[0147] The finally obtained wear-resistant nanofiber-reinforced and protected graphene fiber is composed of a graphene fiber bundle and nanofibers. The nanofibers coat the graphene fiber bundle in the form of a three-dimensional porous network to form a stress buffer layer with a thickness of 15 μm; wear-resistant particles are uniformly loaded inside the three-dimensional porous network;

[0148] Compared with the untreated graphene fiber bundle, the tensile strength of the wear-resistant nanofiber-reinforced and protected graphene fiber is increased by 65%, the tensile elastic modulus is increased by 60%, the toughness is increased by 40%, the electrical conductivity is increased by 18%, the thermal conductivity is increased by 18%, the flexural strength is increased by 65%, the flexural modulus is increased by 75%, the flexural curvature is increased by 25%, and the specific wear rate is reduced by 80%.

[0149] The application of the wear-resistant nanofiber-reinforced and protected graphene fiber has the following specific process: the above-prepared wear-resistant nanofiber-reinforced and protected graphene fiber is woven by a two-dimensional weaving method to obtain a graphene fiber fabric; wherein, the warp density during the weaving process is 40 threads / cm, and the weft density is 15 threads / cm;

[0150] The thickness of the obtained graphene fiber fabric is 2.04 mm, the wear-resistant life is 3×10 4 times, the tensile strength is 650 MPa, the flexural fatigue life is 1.5×10 4 times, the electrical conductivity is 800 S / cm, and the thermal conductivity is 180 W / (m·K);

[0151] Replace the wear-resistant nanofiber-reinforced and protected graphene fiber with the graphene fiber bundle in the above step (1), and prepare a comparison sample according to the same process as the graphene fiber fabric. Compared with the comparison sample, the wear-resistant life of the graphene fiber fabric is increased by 220%, the tensile strength is increased by 50%, the flexural fatigue life is increased by 180%, the electrical conductivity is increased by 12%, and the thermal conductivity is increased by 50%.

[0152] Example 5

[0153] The preparation method of the wear-resistant nanofiber-reinforced and protected graphene fiber is as follows:

[0154] (1) Preparation of raw materials;

[0155] Wear-resistant particles: graphene powder, with an average lateral size of 5 μm and an average thickness of 2 nm;

[0156] Polymer material: polybenzimidazole, manufactured by Dongguan Fulin Plastic Raw Materials Co., Ltd., with the brand name CelazolePBI U60;

[0157] Graphene fiber bundle: First, a GO (graphene oxide, with a lateral size of 10 - 50 μm and a thickness of 1 - 5 nm) / DMF solution with a concentration of 10 mg / g is subjected to wet spinning (the coagulation bath is ethyl acetate) to obtain a graphene oxide fiber bundle. Then, it is soaked in a hydroiodic acid / ethanol solution (the volume ratio of hydroiodic acid to ethanol is 1:3) and chemically reduced at 60 °C to obtain a chemically reduced graphene fiber bundle. After that, it is thermally stretched at 1200 °C to obtain a graphene fiber bundle;

[0158] The number of single graphene fibers in the prepared graphene fiber bundle is 1000. The diameter of the graphene fiber bundle is 1.52 mm, the tensile strength is 600 MPa, the tensile elastic modulus is 60 GPa, and the toughness is 15 MJ / m 3 , the conductivity is 600 S / cm, the thermal conductivity is 150 W / m·K, the flexural strength is 400 MPa, the flexural modulus is 40 GPa, the flexural curvature is 1%, and the specific wear rate is 0.18 mm 3 / (N·m);

[0159] Ethanol: The purity is 99%;

[0160] The solvent in the polymer material solution: N-methylpyrrolidone;

[0161] (2) Prepare the spinning solution;

[0162] First, add the polymer material to the solvent and completely dissolve the polymer material. Then, use a magnetic stirrer to stir at 160 °C for 2 hours until the solution is completely homogeneous to obtain a polymer material solution with a concentration of 10 wt%. Then, add the wear-resistant particles to the polymer material solution and ultrasonicate at a power of 550 W for 45 min, and then continue to stir until the wear-resistant particles are uniformly dispersed in the polymer material solution. Finally, filter the polymer material solution through a filter membrane with a pore size of 0.45 μm to obtain the spinning solution; among them, the mass ratio of the wear-resistant particles to the polymer material is 1:30;

[0163] (3) First, soak and clean the graphene fiber bundle in ethanol for 20 min, then take it out and dry it at 60 °C for 6 h. Then, perform plasma irradiation treatment on the dried graphene fiber bundle in an oxygen atmosphere; among them, the pressure in the reaction chamber is 50 Pa, the oxygen flow rate is 40 sccm, the irradiation power is 80 W, and the treatment time is 100 s;

[0164] (4) Fix the surface-pretreated graphene fiber bundle on an electrospinning nanofiber yarn machine, and then use the spinning solution prepared in step (2) to form a nanofiber membrane by electrospinning and uniformly wrap it on the surface-pretreated graphene fiber bundle, and then wind it into a roll; among them, the average diameter of the fibers in the nanofiber membrane is 400 nm, and the thickness of the nanofiber membrane is 45 μm;

[0165] The spinning process parameters are as follows: voltage 20 kV, distance between the needle and the collector 6 cm, advancing pump rate 1 mL / h, fiber reel wire collection rate 1.5 cm / min, drying temperature 70 °C, spinning time 1 h;

[0166] (5) Perform hot roll treatment on the fiber bundle after winding in step (4) to obtain wear-resistant nanofiber-reinforced protective graphene fibers;

[0167] The process parameters of the hot roll treatment are: roll temperature 230 °C, roll pressure 10 MPa, roll speed 1 m / min, roll gap 110 μm.

[0168] The finally obtained wear-resistant nanofiber-reinforced protective graphene fibers are composed of graphene fiber bundles and nanofibers. The nanofibers coat the graphene fiber bundles in the form of a three-dimensional porous network to form a stress buffer layer with a thickness of 25 μm; wear-resistant particles are uniformly loaded inside the three-dimensional porous network;

[0169] Compared with the untreated graphene fiber bundles, the tensile strength of the wear-resistant nanofiber-reinforced protective graphene fibers is increased by 35%, the tensile elastic modulus is increased by 30%, the toughness is increased by 15%, the electrical conductivity is increased by 25%, the thermal conductivity is increased by 25%, the bending strength is increased by 35%, the bending modulus is increased by 40%, the bending curvature is increased by 10%, and the specific wear rate is reduced by 50%.

[0170] The application of the wear-resistant nanofiber-reinforced protective graphene fibers is as follows: The above-prepared wear-resistant nanofiber-reinforced protective graphene fibers are woven by a two-dimensional weaving method to obtain a graphene fiber fabric; among them, the warp density during the weaving process is 30 roots / cm, and the weft density is 25 roots / cm;

[0171] The thickness of the obtained graphene fiber fabric is 3.65 mm, the wear-resistant life is 5×10^4 times, the tensile strength is 750 MPa, the bending fatigue life is 3×10 4 times, the electrical conductivity is 900 S / cm, and the thermal conductivity is 190 W / (m·K);

[0172] Replace the wear-resistant nanofiber-reinforced protective graphene fibers with the graphene fiber bundles in the above step (1), and prepare a comparison sample according to the same process as the graphene fiber fabric. Compared with the comparison sample, the wear-resistant life of the graphene fiber fabric is increased by 180%, the tensile strength is increased by 30%, the bending fatigue life is increased by 120%, the electrical conductivity is increased by 20%, and the thermal conductivity is increased by 30%.

[0173] Example 6

[0174] The preparation method of the wear-resistant nanofiber-reinforced protective graphene fibers is as follows:

[0175] (1)Preparation of raw materials;

[0176] Wear-resistant particles: Titanium carbide MXene, with an average lateral size of 2 μm and an average thickness of 2 nm;

[0177] Polymer material: Polyimide, manufactured by Jiangsu Aoshen New Materials Co., Ltd., with the brand name of Jialun Fitlon®;

[0178] Graphene fiber tow: First, a GO (graphene oxide, with a lateral size of 10 - 50 μm and a thickness of 1 - 5 nm) / DMF solution with a concentration of 10 mg / g is wet-spun (the coagulation bath is ethyl acetate) to obtain a graphene oxide fiber tow, then it is soaked in a hydroiodic acid / ethanol solution (the volume ratio of hydroiodic acid to ethanol is 1:3) and chemically reduced at 60 °C to obtain a chemically reduced graphene fiber tow, and then thermally drawn at 1200 °C to obtain a graphene fiber tow;

[0179] The number of single graphene fibers in the obtained graphene fiber tow is 2000, the diameter of the graphene fiber tow is 2.10 mm, the tensile strength is 500 MPa, the tensile elastic modulus is 50 GPa, the toughness is 12 MJ / m 3 , the electrical conductivity is 400 S / cm, the thermal conductivity is 120 W / m·K, the flexural strength is 300 MPa, the flexural modulus is 35 GPa, the flexural curvature is 0.80%, and the specific wear rate is 0.2 mm 3 / (N·m);

[0180] Ethanol: The purity is 99%;

[0181] Solvent in the polymer material solution: Dimethylacetamide and N-methylpyrrolidone with a volume ratio of 1:1;

[0182] (2)Preparation of spinning solution;

[0183] First, the polymer material is added to the solvent and completely dissolved, then a magnetic stirrer is used to stir at 85 °C for 4 hours until the solution is completely homogeneous to obtain a polymer material solution with a concentration of 15 wt%, then the wear-resistant particles are added to the polymer material solution and ultrasonicated at a power of 600 W for 1 h and then continue to stir until the wear-resistant particles are uniformly dispersed in the polymer material solution, and finally the polymer material solution is filtered through a filter membrane with a pore size of 0.45 μm to obtain a spinning solution; among them, the mass ratio of the wear-resistant particles to the polymer material is 1:35;

[0184] (3) First, soak the graphene fiber bundle in ethanol for 30 min, then take it out and dry it at 40 °C for 8 h. Then, perform plasma irradiation treatment on the dried graphene fiber bundle in an oxygen atmosphere. Among them, the pressure in the reaction chamber is 60 Pa, the oxygen flow rate is 100 sccm, the irradiation power is 100 W, and the treatment time is 150 s;

[0185] (4) Fix the surface-pretreated graphene fiber bundle on an electrospinning nanofiber yarn machine, and then use the spinning solution prepared in step (2) to form a nanofiber membrane by electrospinning and uniformly wrap it on the surface-pretreated graphene fiber bundle, and then wind it into a roll. Among them, the average diameter of the fibers in the nanofiber membrane is 500 nm, and the thickness of the nanofiber membrane is 65 μm;

[0186] The electrospinning process parameters are: voltage 25 kV, distance between the needle and the collector 7 cm, propelling pump rate 1.5 mL / h, fiber reel winding rate 1.8 cm / min, drying temperature 75 °C, and electrospinning time 1.5 h;

[0187] (5) Perform hot roll treatment on the fiber bundle wound in step (4) to obtain wear-resistant nanofiber-reinforced protective graphene fiber;

[0188] The process parameters of the hot roll treatment are: roller temperature 250 °C, roller pressure 12 MPa, roller speed 1.2 m / min, and roller gap 130 μm.

[0189] The finally obtained wear-resistant nanofiber-reinforced protective graphene fiber is composed of a graphene fiber bundle and nanofibers. The nanofibers coat the graphene fiber bundle in the form of a three-dimensional porous network, forming a stress buffer layer with a thickness of 35 μm; wear-resistant particles are uniformly loaded inside the three-dimensional porous network;

[0190] Compared with the untreated graphene fiber bundle, the tensile strength of the wear-resistant nanofiber-reinforced protective graphene fiber is increased by 40%, the tensile elastic modulus is increased by 50%, the toughness is increased by 30%, the electrical conductivity is increased by 30%, the thermal conductivity is increased by 30%, the bending strength is increased by 45%, the bending modulus is increased by 50%, the bending curvature is increased by 10%, and the specific wear rate is reduced by 60%.

[0191] The application of the wear-resistant nanofiber-reinforced protective graphene fiber is as follows. Specifically, the above-prepared wear-resistant nanofiber-reinforced protective graphene fiber is woven by a three-dimensional weaving method to obtain a graphene fiber fabric. Among them, the proportions of the wear-resistant nanofiber-reinforced protective graphene fiber in the graphene fiber fabric in the 0°, +45°, -45°, and 90° directions are 50%, 12.5%, 12.5%, and 25% in turn;

[0192] The thickness of the prepared graphene fiber fabric is 5.04 mm, the wear resistance life is 2×10^5 times, the tensile strength is 820 MPa, the flexural fatigue life is 8×10 4 times, the electrical conductivity is 1400 S / cm, and the thermal conductivity is 280 W / (m·K);

[0193] Replace the wear-resistant nanofiber-reinforced protective graphene fiber with the graphene fiber tow in the above step (1), and prepare a comparative sample according to the same process as the graphene fiber fabric. Compared with the comparative sample, the wear resistance life of the graphene fiber fabric is increased by 220%, the tensile strength is increased by 50%, the flexural fatigue life is increased by 180%, the electrical conductivity is increased by 18%, and the thermal conductivity is increased by 35%.

[0194] Example 7

[0195] Preparation method of wear-resistant nanofiber-reinforced protective graphene fiber, the steps are as follows:

[0196] (1) Preparation of raw materials;

[0197] Wear-resistant particles: composed of silicon dioxide and alumina with a mass ratio of 1:1, the particle size of silicon dioxide is 50 - 80 nm, and the particle size of alumina is 150 - 200 nm;

[0198] Polymer material: poly(p-phenylene benzobisoxazole), the manufacturer is Chengdu Xinchen New Material Technology Co., Ltd., and the grade is Hou Delun ® PBO pulp;

[0199] Graphene fiber tow: First, a GO (graphene oxide, with a lateral size of 10 - 50 μm and a thickness of 1 - 5 nm) / DMF solution with a concentration of 10 mg / g is wet-spun (the coagulation bath is ethyl acetate) to obtain a graphene oxide fiber tow, and then it is soaked in a hydroiodic acid / ethanol solution (the volume ratio of hydroiodic acid to ethanol is 1:3) and chemically reduced at 60°C to obtain a chemically reduced graphene fiber tow, and then thermally drawn at 1200°C to obtain a graphene fiber tow;

[0200] The number of single graphene fibers in the prepared graphene fiber tow is 3000, the diameter of the graphene fiber tow is 2.54 mm, the tensile strength is 400 MPa, the tensile elastic modulus is 40 GPa, and the toughness is 10 MJ / m 3 , the electrical conductivity is 300 S / cm, the thermal conductivity is 100 W / m·K, the flexural strength is 250 MPa, the flexural modulus is 30 GPa, the flexural curvature is 0.70%, and the specific wear rate is 0.25 mm 3 / (N·m);

[0201] Ethanol: The purity is 99%;

[0202] Solvents in the polymer material solution: N-methylpyrrolidone and dimethyl sulfoximide with a volume ratio of 1:2;

[0203] (2) Prepare the spinning solution;

[0204] First, add the polymer material to the solvent and completely dissolve the polymer material. Then, use a magnetic stirrer to stir at 75 °C for 6 hours until the solution is completely homogeneous to obtain a polymer material solution with a concentration of 18 wt%. Next, add the wear-resistant particles to the polymer material solution and ultrasonicate at a power of 450 W for 1 h, and then continue to stir until the wear-resistant particles are evenly dispersed in the polymer material solution. Finally, filter the polymer material solution through a filter membrane with a pore size of 0.45 μm to obtain the spinning solution; wherein, the mass ratio of the wear-resistant particles to the polymer material is 1:40;

[0205] (3) First, soak and clean the graphene fiber bundle in ethanol for 20 min, then take it out and dry it at 50 °C for 10 h, and then perform plasma irradiation treatment on the dried graphene fiber bundle in an oxygen atmosphere; wherein, the pressure in the reaction chamber is 80 Pa, the oxygen flow rate is 60 sccm, the irradiation power is 150 W, and the treatment time is 200 s;

[0206] (4) Fix the surface-pretreated graphene fiber bundle on an electrospinning nanofiber yarn machine, and then use the spinning solution prepared in step (2) to form a nanofiber membrane by electrospinning and uniformly wrap it on the surface-pretreated graphene fiber bundle, and then wind it into a roll; wherein, the average diameter of the fibers in the nanofiber membrane is 450 nm, and the thickness of the nanofiber membrane is 100 μm;

[0207] The spinning process parameters are: voltage 30 kV, distance between the needle and the collector 8 cm, propelling pump rate 2 mL / h, fiber reel winding rate 0.8 cm / min, drying temperature 80 °C, spinning time 2 h;

[0208] (5) Perform hot roll pressing treatment on the fiber bundle wound in step (4) to obtain wear-resistant nanofiber-reinforced protective graphene fibers;

[0209] The process parameters of the hot roll pressing treatment are: roll temperature 300 °C, roll pressure 15 MPa, roll speed 1.4 m / min, roll gap 150 μm.

[0210] The finally obtained wear-resistant nanofiber-reinforced protective graphene fibers are composed of graphene fiber bundles and nanofibers. The nanofibers coat the graphene fiber bundles in the form of a three-dimensional porous network to form a stress buffer layer with a thickness of 60 μm; wear-resistant particles are evenly loaded inside the three-dimensional porous network;

[0211] Compared with the untreated graphene fiber tow, the tensile strength of the wear-resistant nanofiber-reinforced and protected graphene fiber is increased by 45%, the tensile elastic modulus is increased by 40%, the toughness is increased by 15%, the electrical conductivity is increased by 35%, the thermal conductivity is increased by 35%, the flexural strength is increased by 50%, the flexural modulus is increased by 55%, the flexural curvature is increased by 10%, and the specific wear rate is reduced by 70%.

[0212] The application of the wear-resistant nanofiber-reinforced and protected graphene fiber is as follows: The prepared wear-resistant nanofiber-reinforced and protected graphene fiber is woven by a three-dimensional weaving method to obtain a graphene fiber fabric; among them, the proportions of the wear-resistant nanofiber-reinforced and protected graphene fiber in the graphene fiber fabric in the 0°, +45°, -45°, and 90° directions are 60%, 10%, 10%, and 20% in sequence;

[0213] The prepared graphene fiber fabric has a thickness of 6.10 mm, a wear-resistant life of 1.5×105 times, a tensile strength of 750 MPa, a flexural fatigue life of 6×10 4 times, an electrical conductivity of 1300 S / cm, and a thermal conductivity of 260 W / (m·K);

[0214] Replace the wear-resistant nanofiber-reinforced and protected graphene fiber with the graphene fiber tow in the above step (1), prepare a comparative sample according to the same process as the graphene fiber fabric, and compared with the comparative sample, the wear-resistant life of the graphene fiber fabric is increased by 240%, the tensile strength is increased by 55%, the flexural fatigue life is increased by 160%, the electrical conductivity is increased by 10%, and the thermal conductivity is increased by 30%.

[0215] Example 8

[0216] The preparation method of the wear-resistant nanofiber-reinforced and protected graphene fiber is as follows:

[0217] (1) Preparation of raw materials;

[0218] Wear-resistant particles: alumina, with a particle size of 250 - 300 nm;

[0219] Polymer material: 2,3,5,6-Tetraaminopyridine hydrochloride and 2,5-dihydroxyterephthalic acid are added to polyphosphoric acid (manufacturer: Shanghai Aladdin Biochemical Technology Co., Ltd., product number: P102919) in a molar ratio of 1:1.02 to obtain a mixed solution with a solid content of 15 wt%. Then the system is purged with nitrogen, heated to 60 °C, and evacuated to -0.095 MPa to remove HCl in 2,3,5,6-tetraaminopyridine hydrochloride (tested with pH paper until no HCl gas is evolved), and then heated to 80 °C at a heating rate of 1 °C / min and continued to be heated to 95 °C at 0.5 °C / min and held for 24 h to complete the polycondensation reaction to obtain PIPD polymer;

[0220] Afterwards, the obtained PIPD polymer solution is spun by the dry-jet wet spinning method. Then, the spun fibers are immersed in distilled water until the pH of the system reaches 7 to remove polyphosphoric acid. Finally, they are placed in a blast drying oven at 60 °C to remove the residual water in the fibers, obtaining poly(2,5-dihydroxy-1,4-phenylene pyridinediimidazole) fibers. Among them, the pore diameter of the spinneret is 25 μm, and the coagulation bath is distilled water at 30 °C.

[0221] The average diameter of the obtained poly(2,5-dihydroxy-1,4-phenylene pyridinediimidazole) fibers is 50 μm, the thermal decomposition temperature is 530 °C, and the tensile strength of the as-spun fibers is 1.2 GPa.

[0222] Graphene fiber bundles: First, a GO (graphene oxide, with a lateral size of 10 - 50 μm and a thickness of 1 - 5 nm) / DMF solution with a concentration of 10 mg / g is wet-spun (the coagulation bath is ethyl acetate) to obtain graphene oxide fiber bundles. Then, they are soaked in a hydroiodic acid / ethanol solution (the volume ratio of hydroiodic acid to ethanol is 1:3) and chemically reduced at 60 °C to obtain chemically reduced graphene fiber bundles. Then, they are thermally drawn at 1200 °C to obtain graphene fiber bundles.

[0223] The number of single graphene fibers in the obtained graphene fiber bundles is 3000, the diameter of the graphene fiber bundles is 2.94 mm, the tensile strength is 350 MPa, the tensile elastic modulus is 35 GPa, and the toughness is 8 MJ / m 3 , the electrical conductivity is 200 S / cm, the thermal conductivity is 80 W / m·K, the flexural strength is 200 MPa, the flexural modulus is 25 GPa, the flexural curvature is 0.60%, and the specific wear rate is 0.3 mm 3 / (N·m);

[0224] Ethanol: The purity is 99%;

[0225] The solvent in the polymer material solution: methanesulfonic acid;

[0226] (2) Prepare the spinning solution;

[0227] First, the polymer material is added to the solvent and completely dissolved. Then, it is stirred with a magnetic stirrer at 50 °C for 6 hours until the solution is completely homogeneous, obtaining a polymer material solution with a concentration of 20 wt%. Then, the wear-resistant particles are added to the polymer material solution and sonicated at a power of 300 W for 1 h, and then stirred until the wear-resistant particles are uniformly dispersed in the polymer material solution. Finally, the polymer material solution is filtered through a filter membrane with a pore diameter of 0.22 μm to obtain the spinning solution. Among them, the mass ratio of the wear-resistant particles to the polymer material is 1:50.

[0228] (3) First, soak the graphene fiber bundle in ethanol for 30 min for cleaning, then take it out and dry it at 60 °C for 12 h. After that, perform plasma irradiation treatment on the dried graphene fiber bundle under an oxygen atmosphere. Among them, the pressure in the reaction chamber is 100 Pa, the oxygen flow rate is 100 sccm, the irradiation power is 200 W, and the treatment time is 250 s.

[0229] (4) Fix the surface-pretreated graphene fiber bundle on an electrospinning nanofiber yarn machine, and then use the spinning solution prepared in step (2) to form a nanofiber membrane by electrospinning and uniformly wrap it on the surface-pretreated graphene fiber bundle, and then wind it into a roll. Among them, the average diameter of the fibers in the nanofiber membrane is 800 nm, and the thickness of the nanofiber membrane is 100 μm.

[0230] The electrospinning process parameters are as follows: voltage 35 kV, distance between the needle and the collector 5 cm, propelling pump rate 0.5 mL / h, fiber reel wire winding rate 0.2 cm / min, drying temperature 65 °C, electrospinning time 0.5 h.

[0231] (5) Perform hot roll treatment on the fiber bundle wound in step (4) to obtain wear-resistant nanofiber-reinforced protective graphene fibers.

[0232] The process parameters of the hot roll treatment are as follows: roller temperature 400 °C, roller pressure 18 MPa, roller speed 1.8 m / min, roller gap 180 μm.

[0233] The finally obtained wear-resistant nanofiber-reinforced protective graphene fibers are composed of graphene fiber bundles and nanofibers. The nanofibers coat the graphene fiber bundles in the form of a three-dimensional porous network, forming a stress buffer layer with a thickness of 70 μm. Wear-resistant particles are uniformly loaded inside the three-dimensional porous network.

[0234] Compared with the untreated graphene fiber bundle, the tensile strength of the wear-resistant nanofiber-reinforced protective graphene fibers is increased by 30%, the tensile elastic modulus is increased by 25%, the toughness is increased by 10%, the electrical conductivity is increased by 40%, the thermal conductivity is increased by 50%, the bending strength is increased by 35%, the bending modulus is increased by 40%, the bending curvature is increased by 10%, and the specific wear rate is reduced by 60%.

[0235] The application of the wear-resistant nanofiber-reinforced protective graphene fibers is as follows. Specifically, the obtained wear-resistant nanofiber-reinforced protective graphene fibers are woven by a three-dimensional weaving method to obtain a graphene fiber fabric. Among them, the proportions of the wear-resistant nanofiber-reinforced protective graphene fibers in the graphene fiber fabric in the 0°, +45°, -45°, and 90° directions are 55%, 12.5%, 12.5%, and 20% in turn.

[0236] The thickness of the prepared graphene fiber fabric is 7.06 mm, the wear resistance life is 2.5×104 times, the tensile strength is 880 MPa, the flexural fatigue life is 1×10 5 times, the electrical conductivity is 1500 S / cm, and the thermal conductivity is 300 W / (m·K);

[0237] Replace the wear-resistant nanofiber-reinforced protective graphene fiber with the graphene fiber tow in the above step (1), and prepare a comparative sample according to the same process as the graphene fiber fabric. Compared with the comparative sample, the wear resistance life of the graphene fiber fabric is increased by 180%, the tensile strength is increased by 35%, the flexural fatigue life is increased by 120%, the electrical conductivity is increased by 5%, and the thermal conductivity is increased by 20%.

Claims

1. Preparation method of wear-resistant nanofiber-reinforced protective graphene fiber, characterized in that: Fix the graphene fiber after surface pretreatment on an electrospinning nanofiber yarn machine. Use electrospinning to form a nanofiber membrane and uniformly wrap it around the graphene fiber after surface pretreatment, then wind it into a roll. After that, perform hot roll pressing on the wound fiber bundle to obtain a wear-resistant nanofiber-reinforced protective graphene fiber. The surface pretreatment adopts the method of plasma irradiation treatment; the plasma irradiation treatment uses an oxygen atmosphere. The spinning solution used for electrospinning is obtained by adding wear-resistant particles to a polymer material solution; the wear-resistant particles are one or more of silicon dioxide, alumina, zirconia, boron nitride nanotubes, graphene powder, and titanium carbide MXene, and the polymer material is polyurethane, polyetherimide, poly(m-phenylene isophthalamide), poly(p-phenylene terephthalamide), polybenzimidazole, polyimide, poly(p-phenylene benzobisoxazole) fiber, or poly(2,5-dihydroxy-1,4-phenylene pyridino bisimidazole). The average diameter of the fibers in the nanofiber membrane is 50 - 1000 nm. The process parameters of the hot roll pressing treatment are: roller temperature 160 - 400 °C, roller pressure 5 - 20 MPa, roller speed 0.5 - 2 m / min, and roller gap 80 - 200 μm. Compared with the untreated graphene fiber, the tensile strength of the wear-resistant nanofiber-reinforced protective graphene fiber is increased by 30 - 65%, the tensile elastic modulus is increased by 25 - 60%, the toughness is increased by 10 - 40%, the electrical conductivity is increased by 8 - 40%, the thermal conductivity is increased by 10 - 50%, the bending strength is increased by 35 - 65%, the bending modulus is increased by 40 - 75%, the bending curvature is increased by 10 - 25%, and the specific wear rate is reduced by 50 - 80%.

2. The preparation method of the wear-resistant nanofiber-reinforced protective graphene fiber according to claim 1, wherein, During the plasma irradiation treatment, the pressure in the reaction chamber is 10 - 100 Pa, the oxygen flow rate is 20 - 100 sccm, the irradiation power is 50 - 200 W, and the treatment time is 30 - 300 s.

3. The preparation method of the wear-resistant nanofiber-reinforced protective graphene fiber according to claim 1, characterized in that, The mass ratio of the wear-resistant particles to the polymer material is 1:10 - 50, and the concentration of the polymer material solution is 1 - 20 wt%.

4. The preparation method of the wear-resistant nanofiber-reinforced protective graphene fiber according to claim 1, characterized in that, The spinning process parameters are: voltage 15 - 39 kV, distance between the needle and the collector 5 - 8 cm, propelling pump rate 0.5 - 2 mL / h, fiber reel wire winding rate 0.1 - 2 cm / min, drying temperature 50 - 80 °C, and spinning time 0.5 - 2 h.

5. The preparation method of the wear-resistant nanofiber-reinforced protective graphene fiber according to claim 4, characterized in that, The thickness of the nanofiber membrane is 3 - 100 μm.

6. The wear-resistant nanofiber-reinforced protective graphene fiber prepared by the preparation method according to any one of claims 1 to 5, characterized in that: It includes a graphene fiber bundle and nanofibers. The nanofibers coat the graphene fiber bundle in the form of a three-dimensional porous network to form a stress buffer layer; wear-resistant particles are uniformly loaded inside the three-dimensional porous network.

7. The application of the wear-resistant nanofiber-reinforced protective graphene fiber according to claim 6, characterized in that: It is applied to the weaving preparation of graphene fiber fabrics.

8. The application of the wear-resistant nanofiber-reinforced protective graphene fiber according to claim 7, characterized in that, The weaving method is knitting, two-dimensional weaving, or three-dimensional weaving.

Images