High-strength and conductive heterocyclic aramid composite fiber and preparation method thereof

Abstract

The application discloses a kind of high-strength and conductive heterocyclic aramid composite fiber and preparation method thereof.The application adds single-layer graphene oxide (GO) with size of 2-5um in heterocyclic aramid spinning solution, which accounts for 1-5% of the mass fraction of heterocyclic aramid, to prepare GO uniformly distributed heterocyclic aramid spinning solution by stirring.After degassing, wet spinning is carried out.The nitrogen atmosphere is used in the heat treatment process, and through heat treatment, the graphene oxide in the fiber is reduced to reduced graphene oxide, which gives aramid fiber conductivity.The graphene heterocyclic aramid composite fiber prepared by the method has a strength of 5.75GPa, an elongation at break of 3.68%, an electrical resistivity of 0.5Ω·m and an electrical conductivity of 2.0S / m.The graphene heterocyclic aramid composite fiber has good heat resistance.After being treated at 200℃ for 24 hours, the strength of the graphene heterocyclic aramid composite fiber decreases from 5.75GPa to 4.19GPa, only a decrease of 27%.

Description

Technical Field

[0001] This invention belongs to the field of high-performance fiber preparation technology, specifically relating to a high-strength and conductive heterocyclic aramid composite fiber and its preparation method. Background Technology

[0002] Aramid fibers are widely used in many high-tech fields such as aerospace, military, and protection due to their excellent properties such as high strength, heat resistance, and flame retardancy. However, due to their electrical insulation properties, they cannot be used in some fields that require conductivity, such as electromagnetic shielding. Electromagnetic shielding in extreme environments requires materials with high strength and high temperature resistance. Modifying aramid fibers to give them a certain degree of conductivity can meet the needs of these fields and expand the application range of aramid fibers. Currently, the main methods for modifying aramid fibers to prepare conductive aramid fibers include coating the fiber surface with conductive materials (CN 116815494 B), such as graphene, carbon nanotubes, and Mxene; or using coaxial spinning (CN 109811426 B), where the core material is a conductive material, such as graphene or carbon nanotubes, and the sheath is aramid, resulting in a core-sheath structure aramid composite fiber. After heat treatment, the core material becomes conductive.

[0003] However, conductive fibers made by coating have a conductive layer on the surface of the fiber. During use, the conductive layer is prone to peeling off and wear, and the conductive function is easily lost. In addition, the process is relatively complicated, requiring the finished fiber to be coated and heat-treated. Especially for filament bundles, it is difficult to achieve uniform coating inside and out.

[0004] The coaxial spinning method for preparing conductive fibers presents a challenge. During the spinning process, the different stretchability of the inner and outer layers leads to a significant problem. The outer aramid layer is easily stretched, while the inner conductive materials, such as graphene and carbon nanotubes, are difficult to stretch and will break upon stretching, terminating the conductive path. Therefore, to ensure conductivity, the spinning process cannot involve stretching, resulting in extremely low overall fiber strength. Para-aramid fibers produced by normal spinning processes have a strength of around 3 GPa, while the coaxial spinning process, due to the lack of stretching, yields a strength of only around 300 MPa. Summary of the Invention

[0005] To address the problems of uneven distribution of conductive materials and low fiber strength in conductive fibers prepared by existing technologies, this invention proposes a high-strength and conductive heterocyclic aramid composite fiber and its preparation method. This invention involves adding 1-5% by mass of monolayer graphene oxide (GO) with a size of 2-5 μm to a heterocyclic aramid spinning solution. A heterocyclic aramid spinning solution with uniformly distributed GO is obtained through simple stirring. After degassing, the spinning solution is wet-spun. A nitrogen atmosphere is used during heat treatment. Through heat treatment, the graphene oxide within the fiber is reduced to reduced graphene oxide (rGO). rGO has excellent conductivity and is uniformly distributed within the fiber, forming electronic pathways, thereby endowing the aramid fiber with conductivity.

[0006] One of the technical solutions of this invention is to provide a method for preparing a high-strength and conductive heterocyclic aramid composite fiber, comprising the following steps:

[0007] (1) Add monolayer graphene oxide, accounting for 1-5% of the mass fraction of heterocyclic aramid, to the heterocyclic aramid spinning solution and stir to obtain a heterocyclic aramid spinning solution with uniformly distributed graphene oxide. The solvent of the spinning solution is DMAC. The proportion of GO in the spinning solution is crucial. When the proportion of GO is low, electronic pathways cannot be formed and electrical conductivity is impossible. When the proportion of GO is high, the aggregation of GO will cause a serious decrease in fiber strength. The mass fraction of the heterocyclic aramid in the spinning solution is 2%-3%.

[0008] Furthermore, the size of the monolayer graphene oxide is 2-5 μm.

[0009] (2) After the spinning solution is degassed, the spinneret is inserted into the coagulation bath for wet spinning. The coagulation bath is an aqueous solution of ethanol with a mass fraction of 30-50% at -25-0℃, and composite nascent fibers in a gel state are obtained. The temperature of the coagulation bath is controlled at a low temperature, especially below zero (-25-0℃), which can enhance the hydrogen bonding between aramid molecules and between aramid and GO molecules, thereby achieving a greater stretching ratio.

[0010] (3) The composite nascent fibers in the gel state are introduced into a stretching bath for stretching; the stretching bath is deionized water at 1-25℃;

[0011] Furthermore, the stretching ratio is 2.8-3.2 times.

[0012] (4) Take a hot bath at a temperature of 70-90℃;

[0013] (5) The tube furnace is used for two drying processes at temperatures of 80°C and 150°C respectively;

[0014] (6) Place it in a tube furnace and perform heat treatment under a nitrogen atmosphere by gradient heating method, with a maximum temperature of 400-500℃; the gradient heating method is to heat from 25℃ to the first temperature in 40 minutes, and hold at the first temperature for 60 minutes; heat from the first temperature to the second temperature in 40 minutes, and hold at the second temperature for 40 minutes; heat from the second temperature to the third temperature in 40 minutes, and hold at the third temperature for 30 minutes;

[0015] Furthermore, the first temperature is 150°C, the second temperature is 250°C, and the third temperature is 400°C.

[0016] Furthermore, the gradient heating method also includes heating from a third temperature to a fourth temperature for 30 minutes, and holding at the fourth temperature for 30 minutes; the fourth temperature is 500°C.

[0017] Through heat treatment, the graphene oxide inside the fiber is reduced to reduced graphene oxide (rGO). rGO has excellent electrical conductivity and is uniformly distributed inside the fiber to form an electronic pathway.

[0018] After the nascent fibers undergo coagulation bath, stretching bath, and hot water washing, they require two drying processes to thoroughly remove moisture and solvents before carbonization. Direct carbonization without drying will result in poor strength. Furthermore, if air-atmosphere heat treatment is performed before nitrogen-atmosphere carbonization, the fiber strength will also be poor. A gradient heating method is used during carbonization, with the maximum carbonization temperature controlled between 400-500℃. At lower temperatures, GO reduction is insufficient, resulting in no conductivity; at excessively high temperatures, the fibers are severely damaged, leading to low fiber strength.

[0019] In the gradient heating method, the temperature is slowly increased from room temperature to 150°C. Residual water molecules inside the fiber gradually migrate from the fiber core to the fiber surface and then escape. Maintaining a temperature of 150°C for a certain period ensures that most water molecules are removed. This removal of water molecules helps reduce the distance between fiber polymers, thus laying the foundation for further heating to improve crystallinity.

[0020] Further, the temperature is slowly increased from 150℃ to 250℃. The DMAC solvent molecules inside the fiber gradually migrate from the fiber core to the fiber surface and then escape. Holding at 250℃ for a certain period ensures that most DMAC molecules are removed. Because DMAC molecules form relatively strong hydrogen bonds with the aramid polymer, and because the size and molecular weight of DMCA molecules are much larger than water molecules, a higher temperature is required to remove DMAC molecules. The removal of DMAC molecules further reduces the distance between the aramid polymer molecules, enhancing the hydrogen bonds and other intermolecular forces between them, which is beneficial for increasing the crystallinity of the fiber during subsequent heating.

[0021] The temperature was further increased to 400°C and held for a certain period. At this temperature, the energy provided was sufficient for the oxygen-containing groups on the GO molecules to detach. Therefore, as the temperature increased, the oxygen-containing groups continuously detached from the GO molecules, migrated from the fiber interior to the surface, and then escaped. During this process, GO gradually transformed into rGO, and the formation of rGO endowed the aramid fiber with electrical conductivity. Simultaneously, because water and DMAC molecules had been completely removed at this stage, the aramid polymer was further compressed with increasing temperature, and the distance between molecules further decreased, resulting in a significant increase in the crystallinity within the fiber.

[0022] The temperature is further increased to 500℃ to further remove oxygen-containing groups from the GO molecules and improve fiber crystallinity, as well as to repair some defects within the rGO molecules, thereby improving conductivity and strength. If the temperature is increased further, exceeding 500℃, the decomposition temperature of aramid molecules is surpassed, and some aramid polymers begin to decompose, which will lead to a sharp decrease in fiber strength.

[0023] The second technical solution of this invention provides a high-strength and conductive heterocyclic aramid composite fiber prepared by the above-mentioned method. The graphene heterocyclic aramid composite fiber prepared by this method has a strength of up to 5.75 GPa, an elongation at break of 3.68%, a resistivity of 0.5 Ω•m, and an electrical conductivity of 2.0 S / m. Furthermore, the graphene heterocyclic aramid composite fiber exhibits better heat resistance than pure heterocyclic aramid composite fiber. After treatment at 200℃ for 24 hours, the strength of pure heterocyclic aramid fiber decreased from 5.31 GPa to 3.02 GPa, a decrease of 43%; the strength of the graphene heterocyclic aramid composite fiber decreased from 5.75 GPa to 4.19 GPa, a decrease of 27%.

[0024] The beneficial effects of this invention are:

[0025] 1) By combining small-sized monolayer graphene oxide of DMAC phase with heterocyclic aramid of DMAC phase, a spinning solution with uniform GO distribution can be prepared by simple stirring.

[0026] 2) High-strength conductive aramid fibers can be produced through ordinary wet spinning processes, which is easy to industrialize.

[0027] 3) After proper drying and gradient heating, the addition of GO improves the fiber strength to a certain extent while imparting electrical conductivity to the fiber. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the process of the present invention.

[0029] Figure 2 These are scanning electron microscope images of Example 1 and Comparative Example 1. Detailed Implementation

[0030] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0031] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0032] The embodiments of the present invention will be further described below with reference to several examples.

[0033] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0034] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0035] Example 1

[0036] A 2µm monolayer graphene oxide (GO) was added to a DMAC heterocyclic aramid spinning solution as solvent. The resulting spinning solution, containing 2% heterocyclic aramid with uniformly distributed GO, was prepared by stirring. The nascent fibers were then placed in a coagulation bath at -25°C, consisting of a 30% ethanol-water solution. The gel-state fibers were then placed in a 1°C water stretching bath with a stretch ratio of 3.2 times, followed by a hot water wash at 90°C. After washing, the fibers underwent two continuous drying processes in a tube furnace at temperatures of 80°C and 150°C, respectively. The fibers were then placed in a tube furnace for carbonization under a nitrogen atmosphere. A gradient heating method was used: heating from 25°C to 150°C for 40 minutes, followed by a hold at 150°C for 60 minutes; heating from 150°C to 250°C for 40 minutes, followed by a hold at 250°C for 40 minutes; heating from 250°C to 400°C for 40 minutes, followed by a hold at 400°C for 30 minutes; heating from 400°C to 500°C for 30 minutes, followed by a hold at 500°C for 30 minutes, and then allowing natural cooling to 25°C. The resulting graphene heterocyclic aramid composite fiber had a strength of 5.75 GPa, an elongation at break of 3.68%, a resistivity of 0.5 Ω•m, and an electrical conductivity of 2.0 S / m. Furthermore, the graphene heterocyclic aramid composite fiber exhibited better heat resistance compared to pure heterocyclic aramid composite fibers. After being treated at 200℃ for 24 hours, the strength of pure heterocyclic aramid fiber decreased from 5.3 GPa to 3.02 GPa, a decrease of 43%; the strength of graphene heterocyclic aramid composite fiber decreased from 5.75 GPa to 4.19 GPa, a decrease of 27%.

[0037] Example 2

[0038] A 5µm monolayer graphene oxide (GO) with a size of 5% was added to a DMAC heterocyclic aramid spinning solution. The solution was stirred to obtain a spinning solution with a uniformly distributed GO and a heterocyclic aramid mass fraction of 3%. After degassing, the spinning solution was wet-spun. The spinning process involved introducing the nascent fibers into a coagulation bath at -25°C, consisting of a 30% ethanol-water solution. The fibers in a gel state were then introduced into a water stretching bath at 1°C with a stretch ratio of 2.8 times, followed by a hot water wash at 90°C. After washing, the fibers underwent two continuous drying processes in a tube furnace at temperatures of 80°C and 150°C, respectively. The fibers were then placed in a tube furnace for carbonization under a nitrogen atmosphere. A gradient heating method was used: heating from 25°C to 150°C for 40 minutes, followed by a hold at 150°C for 60 minutes; heating from 150°C to 250°C for 40 minutes, followed by a hold at 250°C for 40 minutes; heating from 250°C to 400°C for 40 minutes, followed by a hold at 400°C for 30 minutes; heating from 400°C to 500°C for 30 minutes, followed by a hold at 500°C for 30 minutes, and then allowing natural cooling to 25°C. The resulting graphene heterocyclic aramid composite fiber had a strength of 3.1 GPa, an elongation at break of 2.68%, a resistivity of 0.1 Ω•m, and an electrical conductivity of 14.4 S / m.

[0039] Example 3

[0040] A 2µm monolayer graphene oxide (GO) with a mass fraction of 1% (by mass) of heterocyclic aramid was added to a DMAC heterocyclic aramid spinning solution to prepare a spinning solution with a uniformly distributed GO and a heterocyclic aramid mass fraction of 2%. After degassing, the spinning solution was subjected to wet spinning. The spinning process involved introducing the nascent fibers into a coagulation bath at 0°C, consisting of a 30% ethanol aqueous solution. The fibers in a gel state were then introduced into a water stretching bath at 1°C with a stretch ratio of 2.8 times, followed by a hot water wash at 70°C. After washing, the fibers underwent two continuous drying processes in a tube furnace at temperatures of 80°C and 150°C, respectively. The fibers were then placed in a tube furnace for carbonization under a nitrogen atmosphere. A gradient heating method was used: the temperature was increased from 25°C to 150°C over 40 minutes, then held at 150°C for 60 minutes; the temperature was increased from 150°C to 250°C over 40 minutes, then held at 250°C for 40 minutes; and the temperature was increased from 250°C to 400°C over 40 minutes, then held at 400°C for 30 minutes, before naturally cooling to 25°C. The resulting graphene heterocyclic aramid composite fiber had a strength of 4.5 GPa, an elongation at break of 3.21%, a resistivity of 15 Ω•m, and an electrical conductivity of 0.2 S / m.

[0041] Example 4

[0042] A 2µm monolayer graphene oxide (GO) with a mass fraction of 1% (by mass) of heterocyclic aramid was added to a DMAC heterocyclic aramid spinning solution. The solution was stirred to obtain a spinning solution with a uniformly distributed GO and a heterocyclic aramid mass fraction of 2%. After degassing, the spinning solution was subjected to wet spinning. The spinning process involved introducing the nascent fibers into a coagulation bath at -25°C, consisting of a 50% ethanol aqueous solution. The fibers in a gel state were then introduced into a water stretching bath at 25°C with a stretch ratio of 3.0 times, followed by a hot water wash at 90°C. After washing, the fibers underwent two continuous drying processes in a tube furnace at temperatures of 80°C and 150°C, respectively. The fibers were then placed in a tube furnace for carbonization under a nitrogen atmosphere. A gradient heating method was used: heating from 25°C to 150°C for 40 minutes, followed by a hold at 150°C for 60 minutes; heating from 150°C to 250°C for 40 minutes, followed by a hold at 250°C for 40 minutes; heating from 250°C to 400°C for 40 minutes, followed by a hold at 400°C for 30 minutes; heating from 400°C to 500°C for 30 minutes, followed by a hold at 500°C for 20 minutes, and then allowing natural cooling to 25°C. The resulting graphene heterocyclic aramid composite fiber had a strength of 4.9 GPa, an elongation at break of 3.99%, a resistivity of 0.8 Ω•m, and an electrical conductivity of 1.5 S / m.

[0043] Comparative Example 1

[0044] DMAC was added to a heterocyclic aramid spinning solution using DMAC as the solvent, and the solution was stirred to obtain a spinning solution with a heterocyclic aramid mass fraction of 2%. After degassing, the spinning solution was subjected to wet spinning. The spinning process involved introducing the nascent fibers into a coagulation bath at -25°C, the coagulation bath consisting of a 30% ethanol aqueous solution. The fibers in the gel state were then introduced into a water stretching bath at 1°C with a stretch ratio of 3.0 times, followed by a hot water wash at 90°C. After washing, the fibers were subjected to two continuous drying stages in a tube furnace at temperatures of 80°C and 150°C, respectively. The fibers were then placed in a tube furnace for carbonization under a nitrogen atmosphere using a gradient heating method: from 25°C to 150°C for 40 minutes, then held at 150°C for 60 minutes; from 150°C to 250°C for 40 minutes, then held at 250°C for 40 minutes; from 250°C to 400°C for 40 minutes, then held at 400°C for 30 minutes; from 400°C to 500°C for 30 minutes, then held at 500°C for 30 minutes, and finally cooled naturally to 25°C. The heterocyclic aramid fibers obtained using this method had a strength of 2.74 GPa and an elongation at break of 2.62%, but the electrical conductivity could not be measured.

[0045] Comparative Example 2

[0046] Monolayer graphene oxide (2-5 μm in size), comprising 1% of the heterocyclic aramid fiber mass, was added to a DMAC heterocyclic aramid spinning solution to obtain a spinning solution with a uniform GO distribution and a heterocyclic aramid fiber mass of 2%. After degassing, the spinning solution was subjected to wet spinning. The spinning process involved introducing the nascent fibers into a coagulation bath at 25°C, consisting of a 30% ethanol-water solution. The fibers in a gel state were then introduced into a water stretching bath at 25°C with a stretch ratio of 2.6 times, followed by a hot water wash at 90°C. After washing, the fibers underwent two continuous drying processes in a tube furnace at temperatures of 80°C and 150°C, respectively. The fibers were then placed in a tube furnace for carbonization under a nitrogen atmosphere using a gradient heating method: from 25°C to 150°C in 40 minutes, followed by a hold at 150°C for 60 minutes; from 150°C to 250°C in 40 minutes, followed by a hold at 250°C for 40 minutes; from 250°C to 400°C in 40 minutes, followed by a hold at 400°C for 30 minutes; and from 400°C to 500°C in 30 minutes, followed by a hold at 500°C for 30 minutes, after which the temperature was allowed to drop naturally to 25°C. The graphene heterocyclic aramid composite fiber prepared using this method had a strength of 2.1 GPa and an elongation at break of 2.31%, but its electrical conductivity could not be measured.

[0047] Comparative Example 3

[0048] A spinning solution containing 2-5 μm monolayer graphene oxide (GO) at a mass fraction of 1% of heterocyclic aramid fibers was prepared by adding GO monolayers to a DMAC heterocyclic aramid spinning solution. The GO was uniformly distributed, resulting in a spinning solution with a 2% mass fraction of heterocyclic aramid fibers. After degassing, the spinning solution was wet-spun. The spinning process involved introducing the nascent fibers into a coagulation bath at -25°C, consisting of a 30% ethanol-water solution. The fibers in a gel state were then introduced into a water stretching bath at 1°C with a stretch ratio of 3.2 times, followed by a hot water wash at 90°C. The fibers were then placed in a tube furnace for carbonization under a nitrogen atmosphere using a gradient heating method: from 25°C to 150°C in 40 minutes, followed by a hold at 150°C for 60 minutes; from 150°C to 250°C in 40 minutes, followed by a hold at 250°C for 40 minutes; from 250°C to 400°C in 40 minutes, followed by a hold at 400°C for 30 minutes; and from 400°C to 500°C in 30 minutes, followed by a hold at 500°C for 30 minutes, after which the temperature was allowed to drop naturally to 25°C. The graphene heterocyclic aramid composite fiber prepared using this method had a strength of 0.92 GPa, an elongation at break of 1.91%, and its electrical conductivity could not be measured.

[0049] Comparative Example 4

[0050] Monolayer graphene oxide (GO) with a size of 2-5 μm, comprising 1% of the heterocyclic aramid by mass, was added to a DMAC heterocyclic aramid spinning solution. The solution was stirred to obtain a spinning solution with a uniformly distributed GO and a heterocyclic aramid mass of 2%. After degassing, the spinning solution was subjected to wet spinning. The spinning process involved introducing the nascent fibers into a coagulation bath at -25°C, consisting of a 30% ethanol-water solution. The fibers in a gel state were then introduced into a water stretching bath at 1°C with a stretch ratio of 3.2 times, followed by a hot water wash at 90°C. After washing, the fibers underwent two continuous drying processes in a tube furnace at 80°C and 150°C, respectively, followed by continuous heat treatment in an air atmosphere at 350°C. The fibers were then placed in a tube furnace for carbonization under a nitrogen atmosphere using a gradient heating method: from 25°C to 150°C in 40 minutes, followed by a hold at 150°C for 60 minutes; from 150°C to 250°C in 40 minutes, followed by a hold at 250°C for 40 minutes; from 250°C to 400°C in 40 minutes, followed by a hold at 400°C for 30 minutes; and from 400°C to 500°C in 30 minutes, followed by a hold at 500°C for 30 minutes, after which the temperature was allowed to drop naturally to 25°C. The graphene heterocyclic aramid composite fiber prepared using this method had a strength of 1.86 GPa and an elongation at break of 2.45%, but its electrical conductivity could not be measured.

[0051] Comparative Example 5

[0052] Monolayer graphene oxide (GO) with a size of 2-5 μm, comprising 1% of the heterocyclic aramid by mass, was added to a DMAC heterocyclic aramid spinning solution. The solution was stirred to obtain a spinning solution with a uniformly distributed GO and a heterocyclic aramid mass of 2%. After degassing, the spinning solution was subjected to wet spinning. The spinning process involved introducing the nascent fibers into a coagulation bath at -25°C, consisting of a 30% ethanol-water solution. The fibers in a gel state were then introduced into a water stretching bath at 1°C with a stretch ratio of 3.2 times, followed by a hot water wash at 90°C. After washing, the fibers underwent two continuous drying processes in a tube furnace at temperatures of 80°C and 150°C, respectively. The fibers were then placed in a tube furnace for carbonization under a nitrogen atmosphere using a gradient heating method: from 25°C to 150°C for 40 minutes, then held at 150°C for 60 minutes; from 150°C to 250°C for 40 minutes, then held at 250°C for 40 minutes; from 250°C to 400°C for 40 minutes, then held at 400°C for 30 minutes; from 400°C to 600°C for 30 minutes, then held at 600°C for 30 minutes, and finally cooled naturally to 25°C. The graphene heterocyclic aramid composite fiber prepared using this method has a strength of 1.35 GPa, an elongation at break of 2.15%, a resistivity of 0.02 Ω•m, and an electrical conductivity of 156.8 S / m.

[0053] Comparative Example 6

[0054] Similar to Example 1, the only difference is that the gradient heating method is not used in the tube furnace; instead, the temperature is directly raised to 500 degrees Celsius at a heating rate of 10°C / min and held for 30 minutes. The graphene heterocyclic aramid composite fiber prepared by this method has a strength of 1.7 GPa, an elongation at break of 1.9%, a resistivity of 5 Ω•m, and an electrical conductivity of 0.2 S / m.

[0055] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

Claims

1. A method for producing a high-strength and conductive heterocyclic aramid composite fiber, characterized by, The preparation method comprises the following steps: (1) adding single-layer graphene oxide with a mass fraction of 1-5% of the heterocyclic aramid in a heterocyclic aramid spinning solution, and stirring to obtain a heterocyclic aramid spinning solution with uniformly distributed graphene oxide, wherein the solvent of the spinning solution is DMAC; (2) after degassing the spinning solution, the spinning nozzle is inserted into a coagulation bath to perform wet spinning, the coagulation bath is an ethanol aqueous solution with a mass fraction of 30-50% and a temperature of-25-0℃, and a composite nascent fiber in a gel state is obtained; (3) the composite nascent fiber in the gel state is stretched in a stretching bath, the stretching bath is deionized water with a temperature of 1-25℃, and the stretching ratio is 2.8-3.2 times; (4) the fiber is washed in a hot water washing bath with a temperature of 70-90℃; (5) the fiber is dried in a tubular furnace in two stages, and the temperatures are 80℃ and 150℃, respectively; (6) the fiber is placed in a tubular furnace to perform heat treatment in a nitrogen atmosphere by a gradient heating method, wherein the gradient heating method comprises the following steps: heating from 25℃ to a first temperature, the first temperature is 150℃, the heating time is 40 minutes, and the fiber is kept at the first temperature for 60 minutes; heating from the first temperature to a second temperature, the second temperature is 250℃, the heating time is 40 minutes, and the fiber is kept at the second temperature for 40 minutes; heating from the second temperature to a third temperature, the third temperature is 400℃, the heating time is 40 minutes, and the fiber is kept at the third temperature for 30 minutes; heating from the third temperature to a fourth temperature, the heating time is 30 minutes, and the fiber is kept at the fourth temperature for 20-30 minutes; and the fourth temperature is 500℃. In step (1), the mass fraction of the heterocyclic aramid in the spinning solution is 2%-3%.

2. The production method according to claim 1, characterized by, In step (1), the size of the single-layer graphene oxide is 2-5μm.

3. The preparation method according to claim 1, characterized in that, 4. A high-strength and conductive heterocyclic aramid composite fiber prepared by the preparation method of claim 1. ​

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