Acyl chloride nitrogen-doped graphene modified aramid III fiber and its preparation method

Abstract

This invention discloses a nitrogen-doped acyl chloride graphene-modified aramid III fiber and its preparation method. The nitrogen-doped acyl chloride graphene is covalently bonded to the aramid III polymer. This invention achieves uniform dispersion of graphene in N,N-dimethylacetamide, an organic solvent required for the preparation of aramid III, through nitrogen doping and Friedel-Crafts acylation treatment. This allows for in-situ polymerization of the graphene and aramid III, enabling their composite formation. The prepared nitrogen-doped acyl chloride graphene forms covalent bonds with aramid III during polymerization, increasing the bonding tightness between graphene and fiber, thereby improving the fiber's mechanical properties. The preparation process is simple, yields high mechanical strength, and is easily industrialized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of modification of heterocyclic aramid, more particularly to acyl chloride doped nitrogen graphene modified aramid III fiber and a preparation method thereof. BACKGROUND

[0002] The macromolecular chain of aramid fiber is directly connected with two benzene rings at least 85% of amide chain (-CONH-), and the full name is "aromatic polyamide fiber". The varieties of aramid fiber mainly include aramid 1313 (meta-aramid), aramid 1414 (para-aramid, also known as aramid II), and aramid III (para-heterocyclic aramid). Heterocyclic aramid has excellent properties such as high strength, high modulus, high temperature resistance, acid resistance, and alkali resistance. Compared with carbon fiber, it has high elongation, plastic damage characteristics, strong dynamic load capacity, and strong local impact resistance, and has incomparable advantages in the fields of aerospace, military, and machinery.

[0003] Carbon material refers to a nanometer carbon material composed of sp 2 Carbon, mainly including graphene, carbon nanotube, and fullerene, has high specific surface area, high electrical conductivity, and high thermal conductivity, and can be used in fibers to improve the wear resistance, strength of the fibers, and increase the electrical conductivity and thermal conductivity of the fibers. There are some patents reported on the use of graphene in aramid fibers, mainly using graphene to cover aramid fibers to better protect aramid fibers from damage by ultraviolet radiation. The existing graphene doping method cannot effectively improve the bonding force between graphene and aramid, and the mechanical properties of the composite fiber are not significantly improved. At the same time, the coating method uses a large amount of graphene raw material, and the post-processing process is complex, and the economic and environmental problems cannot be ignored. SUMMARY

[0004] To solve the above problems, the present application provides an acyl chloride doped nitrogen graphene modified aramid fiber and a preparation method thereof.

[0005] In one aspect, the present application provides an acyl chloride doped nitrogen graphene modified aramid III fiber, wherein the acyl chloride doped nitrogen graphene is connected to the aramid III polymer by a covalent bond.

[0006] According to an embodiment of the present application, the acyl chloride doped nitrogen graphene accounts for 0.01-1 wt% of the aramid III polymer.

[0007] According to another embodiment of the present application, the acyl chloride doped nitrogen graphene has 1-10 layers, a sheet diameter of 0.5-5 μm, and a nitrogen doping amount of 0.1-10%.

[0008] According to another embodiment of the present application, the average particle size D50 of the acyl chloride doped nitrogen graphene particles can be 0.01 μm≤D50≤1 μm.

[0009] According to another embodiment of the present application, the graphene modified aramid III fiber has a breaking strength of 29-35 cN / dtex, an elastic modulus of 800-1200 cN / dtex, and an elongation at break of 3.3-5.7%.

[0010] Another aspect of the present application provides a preparation method of the above-mentioned acyl chloride doped nitrogen-containing graphene modified heterocyclic aramid fiber, comprising: adding the acyl chloride graphene into a polymerization reaction system for forming the aramid III before polymerization of the aramid III polymer, and participating in the polymerization process of the aramid III to form a composite spinning solution.

[0011] According to an embodiment of the present application, the preparation method comprises: S1, configuring an N,N-dimethylacetamide dispersion solution of the acyl chloride doped nitrogen-containing graphene, the dispersion solution containing lithium chloride at a concentration of 0.05-1 wt%, and the water content in the dispersion solution being 0-500 ppm; and S2, pre-dissolving a third monomer and p-phenylenediamine in an N,N-dimethylacetamide solution with a lithium chloride concentration of 0.5-5 wt% under nitrogen protection, then reducing the temperature to-20-10℃, and adding p-phthaloyl chloride in batches, wherein the acyl chloride doped nitrogen-containing graphene dispersion solution is added into the system before the addition of the p-phthaloyl chloride, and finally a composite spinning solution with a polymer spinnable dynamic viscosity of 30000-200000 centipoise is obtained.

[0012] According to another embodiment of the present application, the concentration of the acyl chloride doped nitrogen-containing graphene in the acyl chloride doped nitrogen-containing graphene dispersion solution in the S1 step is 1-10 wt%, and the secondary particle size of the acyl chloride doped nitrogen-containing graphene in the acyl chloride graphene dispersion solution is ≤1.5 μm.

[0013] According to another embodiment of the present application, the p-phenylenediamine in the S2 step comprises chlorine-containing p-phenylenediamine and fluorine-containing p-phenylenediamine, and the third monomer comprises 2-(4-aminophenyl)-5-aminobenzimidazole and 3,4-diamino diphenyl ether.

[0014] According to another embodiment of the present application, the solid content of the composite spinning solution in the S3 step is 2%-8%.

[0015] The present application can make the graphene uniformly dispersed in the organic solvent N,N dimethylacetamide required for preparing aramid III by doping nitrogen in the graphene and performing Friedel-Crafts acylation treatment, and then the graphene can be compounded with the aramid III in the polymerization process of the aramid III by in-situ polymerization. The acyl chloride doped nitrogen-containing graphene prepared in the polymerization process can form a covalent bond with the aramid III, thereby improving the close combination of the graphene and the fiber and the mechanical properties of the fiber. The preparation process is simple, the mechanical strength is high, and the process is easy to be popularized in industry. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Synthesis and polymerization mechanism of acyl chloride doped nitrogen graphene.

[0017] Figure 2 The infrared spectrum of the acyl chloride doped nitrogen graphene process of Example 1, wherein DMAc solution, nitrogen doped graphene DMAc solution, nitrogen doped graphene DMAc solution just added TPC, reaction after DMAc solution respectively.

[0018] Figure 3 The XPS spectrum of the nitrogen doped graphene of Example 1.

[0019] Figure 4 The dispersion and scanning electron microscope of the acyl chloride doped nitrogen graphene of Example 1.

[0020] Figure 5 The Raman spectrum of the nitrogen doped graphene of Example 1 and Comparative Example 3. DETAILED DESCRIPTION

[0021] The typical embodiments embodying the features and advantages of the present application will be described in detail in the following description. It should be understood that the present application can have various changes in different embodiments, which do not deviate from the scope of the present application, and the description and drawings in essence are used for illustration, not for limiting the present application.

[0022] The acyl chloride doped nitrogen graphene modified aramid III fiber of the present application, the acyl chloride doped nitrogen graphene is connected with aramid III polymer through covalent bond. The acyl chloride doped nitrogen graphene can form covalent bond with aramid III in the polymerization process, thereby improving the combination tightness of graphene and fiber, and improving the mechanical properties of the fiber.

[0023] In an alternative embodiment, the acyl chloride doped nitrogen graphene modified aramid fiber, the acyl chloride doped nitrogen graphene accounts for 0.01-1wt% of aramid III polymer. When the amount of acyl chloride doped nitrogen graphene is less than 0.01wt%, the improvement of the mechanical properties of the fiber is not great; when it is higher than 1wt%, the spinning effect will be affected, and the hole blocking phenomenon is easy to occur. Those skilled in the art can select any value within the above range according to actual needs, for example but not limited to 0.01wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt% and the like.

[0024] In an alternative embodiment, the number of layers of the acyl chloride doped nitrogen graphene can be 1-10 layers, for example 1 layer, 3 layers, 5 layers, 6 layers, 8 layers, 10 layers and the like.

[0025] In an optional embodiment, the acyl chloride doped nitrogen-doped graphene can have a flake size of 0.5-5 μm, such as 0.5 μm, 1 μm, 2 μm, 5 μm, etc. If the acyl chloride doped nitrogen-doped graphene in the modified fiber has a flake size less than 0.5 μm, the intrinsic structure of the graphene is severely damaged, which is not conducive to the improvement of the mechanical properties. If the flake size is greater than 5 μm, it is not conducive to the subsequent spinning process, and the hole blocking phenomenon is prone to occur.

[0026] In an optional embodiment, the nitrogen-doped graphene can have a nitrogen doping amount of 0.1-10 wt%. If the content of the nitrogen-doped graphene in the modified fiber is less than 0.1 wt%, the improvement of the mechanical properties is not obvious. If the content is greater than 10 wt%, the intrinsic structure of the graphene is severely damaged, which is not conducive to the improvement of the mechanical properties. The specific nitrogen doping amount can be selected according to actual needs, such as but not limited to 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0027] In an optional embodiment, the acyl chloride doped nitrogen-doped graphene particles can have an average particle size D50 of 0.01 μm≤D50≤1 μm. If the particle size of the acyl chloride doped nitrogen-doped graphene particles is less than 0.01 microns, the intrinsic structure of the graphene is severely damaged, the mechanical properties are decreased, and the improvement of the fiber properties is not conducive. If the particle size is greater than 1 micron, the spinning effect is not good, and the hole blocking phenomenon is prone to occur.

[0028] In an optional embodiment, the graphene modified aramid III fiber has a breaking strength of 29-35 cN / dtex, an elastic modulus of 800-1200 cN / dtex, and an elongation at break of 3.3-5.7%.

[0029] The acyl chloride doped nitrogen-doped graphene modified aramid III fiber of the present application adds the acyl chloride graphene to the aramid III polymerization reaction system before the polymerization of the aramid III polymer, participates in the polymerization process of the aramid III to form a composite spinning solution. Through this process, the acyl chloride doped nitrogen-doped graphene can be compounded with aramid III by in-situ polymerization. The prepared acyl chloride doped nitrogen-doped graphene can form a covalent bond with aramid III during the polymerization process, which improves the bonding density of graphene and fiber, thereby improving the mechanical properties of the fiber. The preparation process is simple, the mechanical strength is high, and it is easy to popularize in industry.

[0030] Further, first doping nitrogen in graphene and Friedel-Crafts acylation treatment can make graphene uniformly dispersed in the organic solvent N,N-dimethylacetamide required for preparing aramid III, and then adding further improves the uniformity of graphene in the modified fiber during the polymerization process of aramid III, so that the performance of the fiber is stable.

[0031] The preparation process of the modified fiber of the present invention may include: S1, preparing an N,N-dimethylacetamide dispersion of nitrogen-doped graphene with acyl chloride, wherein the dispersion contains lithium chloride at a concentration of 0.05-1 wt% and water content in the dispersion is 0-500 ppm; and S2, pre-dissolving the third monomer and p-phenylenediamine in an N,N-dimethylacetamide solution with a lithium chloride concentration of 0.5-5 wt% under nitrogen protection, then lowering the temperature to -20-10°C, adding terephthaloyl chloride in batches, wherein the nitrogen-doped graphene dispersion with acyl chloride is added to the system before the addition of terephthaloyl chloride, and finally obtaining a composite spinning solution with a polymer spinnable dynamic viscosity of 30,000-200,000 centipoise.

[0032] In step S1, the mechanism for preparing the N,N-dimethylacetamide dispersion of nitrogen-doped acyl chloride graphene is as follows: Figure 1 As shown, nitrogen-doped graphene is dispersed in N,N-dimethylacetamide. Pyrrole nitrogen and terephthaloyl chloride (TPC) undergo a Friedel-Crafts acylation reaction in the presence of LiCl (catalyst), followed by salt formation of pyridine nitrogen and terephthaloyl chloride, to obtain nitrogen-doped graphene with acyl chloride. The concentration of terephthaloyl chloride is 0.1–5%; the reaction temperature is 10–30°C; and the reaction time is 2–8 h. Preferably, the concentration of terephthaloyl chloride is 0.3–3% wt, such as 0.5% wt, 0.8% wt, 1% wt, 2% wt, 3% wt, etc. The preferred reaction temperature is 20–28°C, such as 23°C, 25°C, 28°C, etc. The preferred reaction time is 3–6 h, such as 3 h, 4 h, 5 h, 6 h, etc.

[0033] In the dispersion, the number of layers of nitrogen-doped acyl chloride graphene can be 1 to 10, such as 2, 5, 6, or 8 layers. The average particle size D50 of the nitrogen-doped acyl chloride graphene particles in the dispersion can be 0.01 μm ≤ D50 ≤ 1 μm, preferably 0.1 μm ≤ D50 ≤ 0.4 μm, such as 0.1 μm, 0.2 μm, or 0.3 μm.

[0034] The concentration of nitrogen-doped acyl chloride graphene in the resulting dispersion is 1–10 wt%. A concentration less than 1 wt% will affect the subsequent polymerization process; a concentration greater than 10 wt% will be detrimental to the dispersion of nitrogen-doped graphene during polymerization. To improve dispersibility, a concentration of 1–5 wt% is preferred, such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%. The secondary particle size in the acyl chloride graphene dispersion is ≤1.5 μm.

[0035] The concentration of lithium chloride in the dispersion is 0.05–1 wt%. In step S1, lithium chloride acts as a catalyst for the Friedel-Crafts acylation reaction. To achieve optimal catalytic performance, the preferred concentration of lithium chloride is 0.08–0.8% wt, such as 0.08% wt, 0.1% wt, 0.3% wt, 0.5% wt, and 0.7% wt. To ensure subsequent polymerization, the water content in the dispersion should be below 500 ppm. To ensure the water content in the dispersion is below 500 ppm, the lithium chloride can be dried first. The drying step can be to bake the lithium chloride in a high-temperature furnace at 100°C for 1 hour, then immediately raise the temperature to 400°C and dry for 2 hours. Other drying steps are also possible.

[0036] In step S2, the third monomer and p-phenylenediamine are pre-dissolved in a 0.5-5 wt% N,N-dimethylacetamide solution containing lithium chloride under nitrogen protection. The temperature is then lowered to -20 to 10°C, and terephthaloyl chloride is added in batches. The nitrogen-doped graphene dispersion with acyl chloride is added to the system before the addition of terephthaloyl chloride. In the polymerization system, such as... Figure 1 As shown, nitrogen-doped acyl chloride graphene forms covalent bonds with aramid III, thereby improving the bonding tightness between graphene and fiber and achieving the goal of improving the mechanical properties of fiber.

[0037] In an optional embodiment, the addition method for the acyl chloride nitrogen-doped graphene dispersion containing functional groups such as carbonyl and carboxyl groups that can react with p-phenylenediamine or the third monomer is as follows: the acyl chloride graphene dispersion should be added all at once after the prepolymerization reaction is completed, i.e., when the amount of terephthaloyl chloride added is ≥97%, and filtered with a 400-mesh filter before addition.

[0038] In an optional embodiment, the addition method for acyl chloride graphene dispersions that do not contain functional groups such as carbonyl or carboxyl groups that can react with p-phenylenediamine or the third monomer is to add them in 1-3 times before the reaction or throughout the prepolymerization process to ensure uniform dispersion, and to filter them with a 400-mesh filter before adding them.

[0039] In optional embodiments, p-phenylenediamine includes chlorinated p-phenylenediamine and fluorinated p-phenylenediamine. The third monomer includes 2-(4-aminophenyl)-5-aminobenzimidazole and 3,4-diaminodiphenyl ether.

[0040] In an optional embodiment, the solid content of the nitrogen-doped acyl chloride graphene / heterocyclic aramid composite spinning solution is 2%-8%.

[0041] In step S2, an acyl chloride / heterocyclic aramid composite spinning solution with a spinnable dynamic viscosity of 30,000-200,000 centipoise is finally obtained.

[0042] After step S2, the composite spinning solution is degassed, filtered, coagulated, washed, oiled, dried, and hot-drawn to obtain acyl chloride nitrogen-doped graphene-modified aramid III fibers. Specifically, the process can be as follows: the composite spinning solution is placed in a degassed vessel for degasing; after degasing, the spinning solution is transported to a filter for filtration; after filtration, it is transported to a metering pump for spinning; the spinning solution is extruded through the metering pump into a coagulation bath (DMAc:water = 3:7, temperature 0℃-30℃) and negatively stretched to form nascent fibers; the nascent fibers are washed (temperature 40℃), oiled, dried, and hot-drawn to obtain hot-drawn fibers; finally, they are wound to obtain acyl chloride nitrogen-doped graphene-modified heterocyclic aramid fibers.

[0043] The present invention will be further described below through specific examples. However, these examples are merely exemplary and do not constitute any limitation on the scope of protection of the present invention.

[0044] Unless otherwise specified, all reagents, materials and instruments used in the following examples and comparative examples are commercially available.

[0045] Example 1

[0046] Weigh 11.8 g of nitrogen-doped graphene (1–10 layers, 0.5–5 μm diameter, 1.9% nitrogen content) and 600 g of N,N-dimethylacetamide. Sonicate the mixture at 60 W for 1 h under nitrogen atmosphere using an ultrasonic cell disruptor (0.01 μm ≤ D50 ≤ 1 μm). Simultaneously, weigh 517.5 g of N,N-dimethylacetamide into a reaction vessel, purge with nitrogen, and add 0.112 g of lithium chloride while stirring. After dissolving, add 4.87 g of terephthaloyl chloride. Once dissolved, add the ultrasonically dispersed nitrogen-doped graphene dispersion (0.01 μm ≤ D50 ≤ 1 μm) and stir at room temperature for 5 h to obtain an acyl chloride nitrogen-doped graphene dispersion.

[0047] Weigh 1.5 kg of LiCl into a crucible, dry it in a high-temperature furnace at 100°C for 1 hour, then raise the temperature to 400°C and dry it for 2 hours. After drying, place it in a glove box for later use.

[0048] Nitrogen gas was introduced, and 34 kg of N,N-dimethylacetamide was weighed into a jacketed reactor. Stirring was started, followed by the addition of 1.225 kg of LiCl. After dissolving, 219.94 g of p-phenylenediamine and 684.16 g of 2-(4-aminophenyl)-5-aminobenzimidazole were added. A cold water bath was introduced to lower the temperature. When the temperature reached 12°C, 7.8 g of a well-dispersed nitrogen-doped graphene acyl chloride dispersion (filtered through a 400-mesh screen before addition) was added. The mixture was stirred for 30 minutes, followed by the addition of 1001.30 g of terephthaloyl chloride. The temperature was then rapidly increased to 18–22°C. Once the temperature began to decrease, the cold water bath was removed. After reacting for 40 minutes, 30.97 g of terephthaloyl chloride was added, and the reaction was continued for another 30 minutes. The reaction was then stopped, and the viscosity was measured.

[0049] The above solution was degassed at normal pressure for 7 hours. After degassed, the spinning solution was transported to a filter for filtration. After filtration, it was transported to a metering pump for spinning. The spinning solution was extruded through the metering pump into a coagulation bath (DM Ac: water = 3:7, temperature 0℃-30℃). After negative stretching, nascent fibers were formed. The nascent fibers were washed with water (temperature 40℃), oiled, dried (400℃), and hot-drawn. Finally, they were wound into a cylinder to obtain graphene-modified heterocyclic aramid fibers with a breaking strength of 34.1 cN / dtex, an elastic modulus of 830 cN / dtex, and an elongation at break of 4.04%.

[0050] Figure 2 The infrared spectra of nitrogen-doped graphene during the acyl chloride process are shown, including DMAc solution, DMAc solution with nitrogen-doped graphene, DMAc solution with TPC just added, and DMAc solution after the reaction. The figures show that pyrrole nitrogen is indeed present on the nitrogen-doped graphene, and it undergoes a Friedel-Crafts acylation reaction with TPC in the presence of LiCl.

[0051] Figure 3 The XPS spectrum of nitrogen-doped graphene is shown. The graph clearly shows that nitrogen (N) is present on the graphene, specifically pyrrole nitrogen.

[0052] Figure 4 The dispersion diagram and scanning electron microscope image of nitrogen-doped graphene with acyl chloride are shown. The images show that the nitrogen-doped graphene is well dispersed in DMAc, and no obvious stratification is observed after 24 hours.

[0053] Example 2

[0054] Weigh 11.8 g of nitrogen-doped graphene (1–10 layers, 0.5–5 μm diameter, 1.9% nitrogen content) and 600 g of N,N-dimethylacetamide. Sonicate the mixture at 60 W for 1 h under nitrogen atmosphere using an ultrasonic cell disruptor (0.01 μm ≤ D50 ≤ 1 μm). Simultaneously, weigh 517.5 g of N,N-dimethylacetamide into a reaction vessel, purge with nitrogen, and add 0.112 g of lithium chloride while stirring. After dissolving, add 4.87 g of terephthaloyl chloride. Once dissolved, add the ultrasonically dispersed nitrogen-doped graphene dispersion (0.01 μm ≤ D50 ≤ 1 μm) and stir at room temperature for 5 h to obtain an acyl chloride nitrogen-doped graphene dispersion.

[0055] Weigh 1.5 kg of LiCl into a crucible, dry it in a high-temperature furnace at 100°C for 1 hour, then raise the temperature to 400°C and dry it for 2 hours. After drying, place it in a glove box for later use.

[0056] Nitrogen gas was introduced, and 34 kg of N,N-dimethylacetamide was weighed into a jacketed reactor. Stirring was started, followed by the addition of 1.225 kg of LiCl. After dissolving, 219.94 g of p-phenylenediamine and 684.16 g of 2-(4-aminophenyl)-5-aminobenzimidazole were added. A cold water bath was introduced to lower the temperature. When the temperature reached 12°C, 3.9 g of a well-dispersed nitrogen-doped graphene acyl chloride dispersion (filtered through a 400-mesh screen before addition) was added. Stirring was continued for 30 minutes, followed by the addition of 1001.30 g of terephthaloyl chloride. The temperature was then rapidly increased to 18–22°C. Once the temperature began to decrease, the cold water bath was removed. After reacting for 40 minutes, 30.97 g of terephthaloyl chloride was added, and the reaction was continued for another 30 minutes. The reaction was then stopped, and the viscosity was measured.

[0057] The above solution was degassed at normal pressure for 7 hours. After degassed, the spinning solution was transported to a filter for filtration. After filtration, it was transported to a metering pump for spinning. The spinning solution was extruded through the metering pump into a coagulation bath (DM Ac: water = 3:7, temperature 0℃-30℃). After negative stretching, nascent fibers were formed. The nascent fibers were washed with water (temperature 40℃), oiled, dried (400℃), and hot-drawn. Finally, they were wound into a cylinder to obtain graphene-modified heterocyclic aramid fibers with a breaking strength of 30.7 cN / dtex, an elastic modulus of 790 cN / dtex, and an elongation at break of 3.85%.

[0058] Example 3

[0059] Weigh 23.6 g of nitrogen-doped graphene (1–10 layers, 0.5–5 μm diameter, 1.9% nitrogen content) and 1200 g of N,N-dimethylacetamide. Sonicate the mixture at 60 W for 1 h under nitrogen atmosphere using an ultrasonic cell disruptor. Simultaneously, weigh 1.035 kg of N,N-dimethylacetamide into a reaction vessel, purge with nitrogen, and add 0.224 g of lithium chloride while stirring. After dissolving, add 9.74 g of terephthaloyl chloride. Once dissolved, add the ultrasonically dispersed nitrogen-doped graphene dispersion (0.01 μm ≤ D50 ≤ 1 μm). Stir at room temperature for 5 h to obtain an acyl chloride nitrogen-doped graphene dispersion.

[0060] Weigh 1.5 kg of LiCl into a crucible, dry it in a high-temperature furnace at 100°C for 1 hour, then raise the temperature to 400°C and dry it for 2 hours. After drying, place it in a glove box for later use.

[0061] Nitrogen gas was introduced, and 34 kg of N,N-dimethylacetamide was weighed into a jacketed reactor. Stirring was started, followed by the addition of 1.225 kg of LiCl. After dissolving, 219.94 g of p-phenylenediamine and 684.16 g of 2-(4-aminophenyl)-5-aminobenzimidazole were added. A cold water bath was introduced to lower the temperature. When the temperature reached 12°C, 15.6 g of a well-dispersed nitrogen-doped graphene acyl chloride dispersion (filtered through a 400-mesh screen before addition) was added. Stirring was continued for 30 minutes, followed by the addition of 1001.30 g of terephthaloyl chloride. The temperature was then rapidly increased to 18–22°C. Once the temperature began to decrease, the cold water bath was removed. After reacting for 40 minutes, 30.97 g of terephthaloyl chloride was added, and the reaction was continued for another 30 minutes. The reaction was then stopped, and the viscosity was measured.

[0062] The above solution was degassed at normal pressure for 7 hours. After degassed, the spinning solution was transported to a filter for filtration. After filtration, it was transported to a metering pump for spinning. The spinning solution was extruded through the metering pump into a coagulation bath (DM Ac: water = 3:7, temperature 0℃-30℃). After negative stretching, nascent fibers were formed. The nascent fibers were washed with water (temperature 40℃), oiled, dried (400℃), and hot-drawn. Finally, they were wound into a cylinder to obtain graphene-modified heterocyclic aramid fibers with a breaking strength of 32.0 cN / dtex, an elastic modulus of 810 cN / dtex, and a breaking elongation of 3.98%.

[0063] Example 4

[0064] Weigh 11.8 g of nitrogen-doped graphene (1–10 layers, 0.5–5 μm diameter, 1.9% nitrogen content) and 600 g of N,N-dimethylacetamide. Sonicate the mixture at 60 W for 1 h under nitrogen atmosphere using an ultrasonic cell disruptor (0.01 μm ≤ D50 ≤ 1 μm). Simultaneously, weigh 517.5 g of N,N-dimethylacetamide into a reaction vessel, purge with nitrogen, and add 0.112 g of lithium chloride while stirring. After dissolving, add 9.74 g of terephthaloyl chloride. Once dissolved, add the ultrasonically dispersed nitrogen-doped graphene dispersion and stir at room temperature for 5 h to obtain an acyl chloride nitrogen-doped graphene dispersion (0.01 μm ≤ D50 ≤ 1 μm).

[0065] Weigh 1.5 kg of LiCl into a crucible, dry it in a high-temperature furnace at 100°C for 1 hour, then raise the temperature to 400°C and dry it for 2 hours. After drying, place it in a glove box for later use.

[0066] Nitrogen gas was introduced, and 34 kg of N,N-dimethylacetamide was weighed into a jacketed reactor. Stirring was started, followed by the addition of 1.225 kg of LiCl. After dissolving, 219.94 g of p-phenylenediamine and 684.16 g of 2-(4-aminophenyl)-5-aminobenzimidazole were added. A cold water bath was introduced to lower the temperature. When the temperature reached 12°C, 7.8 g of a well-dispersed nitrogen-doped graphene acyl chloride dispersion (filtered through a 400-mesh screen before addition) was added. The mixture was stirred for 30 minutes, followed by the addition of 1001.30 g of terephthaloyl chloride. The temperature was then rapidly increased to 18–22°C. Once the temperature began to decrease, the cold water bath was removed. After reacting for 40 minutes, 30.97 g of terephthaloyl chloride was added, and the reaction was continued for another 30 minutes. The reaction was then stopped, and the viscosity was measured.

[0067] The above solution was degassed at normal pressure for 7 hours. After degassed, the spinning solution was transported to a filter for filtration. After filtration, it was transported to a metering pump for spinning. The spinning solution was extruded through the metering pump into a coagulation bath (DM Ac: water = 3:7, temperature 0℃-30℃). After negative stretching, nascent fibers were formed. The nascent fibers were washed with water (temperature 40℃), oiled, dried (400℃), and hot-drawn. Finally, they were wound into a cylinder to obtain graphene-modified heterocyclic aramid fibers with a breaking strength of 33.2 cN / dtex, an elastic modulus of 823 cN / dtex, and a breaking elongation of 3.84%.

[0068] Comparative Example 1

[0069] Weigh 1.5 kg of LiCl into a crucible, dry it in a high-temperature furnace at 100°C for 1 hour, then raise the temperature to 400°C and dry it for 2 hours. After drying, place it in a glove box for later use.

[0070] Nitrogen gas was introduced, and 34 kg of N,N-dimethylacetamide was weighed into a jacketed reactor. Stirring was started, followed by the addition of 1.225 kg of LiCl. After dissolving, 219.94 g of p-phenylenediamine and 684.16 g of 2-(4-aminophenyl)-5-aminobenzimidazole were added. A cold water bath was introduced to begin cooling. When the temperature reached 10°C, 1001.30 g of terephthaloyl chloride was added. The temperature was then rapidly increased to 18–22°C. Once the temperature began to decrease, the cold water bath was removed. After reacting for 40 minutes, 30.97 g of terephthaloyl chloride was added, and the reaction was continued for another 30 minutes. The reaction was then stopped, and the viscosity was measured.

[0071] The above solution was degassed at normal pressure for 7 hours. After degassed, the spinning solution was transported to a filter for filtration. After filtration, it was transported to a metering pump for spinning. The spinning solution was extruded through the metering pump into a coagulation bath (DM Ac: water = 3:7, temperature 0℃-30℃). After negative stretching, nascent fibers were formed. The nascent fibers were washed with water (temperature 40℃), oiled, dried (400℃), and hot-drawn. Finally, they were wound into a cylinder to obtain heterocyclic aramid fibers with a breaking strength of 27.8 cN / dtex, an elastic modulus of 780 cN / dtex, and a breaking elongation of 3.74%.

[0072] Comparative Example 2

[0073] Weigh 11.8g of nitrogen-doped graphene (1-10 layers, 0.5-5μm in diameter, and 1.9% nitrogen content) and 600g of N,N-dimethylacetamide. Use an ultrasonic cell disruptor to sonicate at 60W for 1h under nitrogen atmosphere (0.01μm≤D50≤1μm).

[0074] Weigh 1.5 kg of LiCl into a crucible, dry it in a high-temperature furnace at 100°C for 1 hour, then raise the temperature to 400°C and dry it for 2 hours. After drying, place it in a glove box for later use.

[0075] Nitrogen gas was introduced, and 34 kg of N,N-dimethylacetamide was weighed into a jacketed reactor. Stirring was started, followed by the addition of 1.225 kg of LiCl. After dissolving, 219.94 g of p-phenylenediamine and 684.16 g of 2-(4-aminophenyl)-5-aminobenzimidazole were added. A cold water bath was introduced to lower the temperature. When the temperature reached 12°C, 7.8 g of a well-dispersed nitrogen-doped graphene dispersion (0.01 μm ≤ D50 ≤ 1 μm) was added, filtered through a 400-mesh screen before addition. Stirring was continued for 30 minutes, followed by the addition of 1001.30 g of terephthaloyl chloride. The temperature was then rapidly increased to 18–22°C. Once the temperature began to decrease, the cold water bath was removed. After reacting for 40 minutes, 30.97 g of terephthaloyl chloride was added, and the reaction was continued for another 30 minutes. The reaction was then stopped, and the viscosity was measured.

[0076] The above solution was degassed at normal pressure for 7 hours. After degassed, the spinning solution was transported to a filter for filtration. After filtration, it was transported to a metering pump for spinning. The spinning solution was extruded through the metering pump into a coagulation bath (DM Ac: water = 3:7, temperature 0℃-30℃). After negative stretching, nascent fibers were formed. The nascent fibers were washed with water (temperature 40℃), oiled, dried (400℃), and hot-drawn. Finally, they were wound into a cylinder to obtain graphene-modified heterocyclic aramid fibers with a breaking strength of 30.3 cN / dtex, an elastic modulus of 800 cN / dtex, and a breaking elongation of 3.82%.

[0077] Comparative Example 3

[0078] 11.8 g of nitrogen-doped graphene (1–10 layers, 0.5–5 μm diameter, 3.5% nitrogen content) and 600 g of N,N-dimethylacetamide were weighed and sonicated at 60 W for 1 h under nitrogen atmosphere using an ultrasonic cell disruptor (0.01 μm ≤ D50 ≤ 1 μm). Simultaneously, 517.5 g of N,N-dimethylacetamide was weighed into a reaction vessel, and 0.112 g of lithium chloride was added while stirring under nitrogen atmosphere. After dissolution, 4.87 g of terephthaloyl chloride was added. After dissolution, the ultrasonically dispersed nitrogen-doped graphene dispersion was added, and the mixture was stirred at room temperature for 5 h to obtain an acyl chloride nitrogen-doped graphene dispersion.

[0079] Weigh 1.5 kg of LiCl into a crucible, dry it in a high-temperature furnace at 100°C for 1 hour, then raise the temperature to 400°C and dry it for 2 hours. After drying, place it in a glove box for later use.

[0080] Nitrogen gas was introduced, and 34 kg of N,N-dimethylacetamide was weighed into a jacketed reactor. Stirring was started, followed by the addition of 1.225 kg of LiCl. After dissolving, 219.94 g of p-phenylenediamine and 684.16 g of 2-(4-aminophenyl)-5-aminobenzimidazole were added. A cold water bath was introduced to lower the temperature. When the temperature reached 12°C, 7.8 g of a well-dispersed nitrogen-doped graphene acyl chloride dispersion (0.01 μm ≤ D50 ≤ 1 μm) was added, filtered through a 400-mesh screen before addition. Stirring was continued for 30 minutes, followed by the addition of 1001.30 g of terephthaloyl chloride. The temperature was then rapidly increased to 18–22°C. Once the temperature began to decrease, the cold water bath was removed. After reacting for 40 minutes, 30.97 g of terephthaloyl chloride was added, and the reaction was continued for another 30 minutes. The reaction was then stopped, and the viscosity was measured.

[0081] The above solution was degassed at normal pressure for 7 hours. After degassed, the spinning solution was transported to a filter for filtration. After filtration, it was transported to a metering pump for spinning. The spinning solution was extruded through the metering pump into a coagulation bath (DM Ac: water = 3:7, temperature 0℃-30℃). After negative stretching, nascent fibers were formed. The nascent fibers were washed with water (temperature 40℃), oiled, dried (400℃), and hot-drawn. Finally, they were wound into a cylinder to obtain graphene-modified heterocyclic aramid fibers with a breaking strength of 34.1 cN / dtex, an elastic modulus of 830 cN / dtex, and an elongation at break of 4.04%.

[0082] Figure 5 Raman spectra of nitrogen-doped graphene with acyl chloride from Example 1 and Comparative Example 3 are shown. The figures show that with increasing nitrogen content, higher Ig is exhibited. D / I G This indicates that nitrogen doping increases the number of defects in graphene.

[0083] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing acyl chloride modified nitrogen-doped graphene modified aramid III fiber, characterized in that, Comprising: S1, configuring an N,N-dimethylacetamide dispersion solution of acyl chloride doped nitrogen graphene, the dispersion solution containing lithium chloride with a concentration of 0.05-1wt%, and the water content in the dispersion solution being 0-500ppm; S2, pre-dissolving a third monomer and p-phenylenediamine in an N,N-dimethylacetamide solution with a lithium chloride concentration of 0.5-5wt% under nitrogen protection, then reducing the temperature to-20-10℃, adding p-terephthaloyl chloride in batches, and adding the dispersion solution to the system before adding p-terephthaloyl chloride, finally obtaining a composite spinning solution with a dynamic viscosity of 30000-200000 centipoise; Wherein, the acyl chloride doped nitrogen graphene is connected to the aramid III polymer through a covalent bond, the acyl chloride doped nitrogen graphene accounts for 0.01-1wt% of the aramid III polymer, the acyl chloride doped nitrogen graphene has 1-10 layers, a flake diameter of 0.5-5μm, a nitrogen doping amount of 0.1-10wt%, and an average particle size D50 of 0.01μm≤D50≤1μm.

2. The production method according to claim 1, characterized by, The concentration of the acyl chloride doped nitrogen graphene in the dispersion solution in the S1 step is 1-10wt%, and the secondary particle size of the acyl chloride doped nitrogen graphene in the dispersion solution is ≤1.5μm.

3. The production method according to claim 1, characterized by, The third monomer in the S2 step includes 2-(4-aminophenyl)-5-aminobenzimidazole.

4. The method of claim 1, wherein, The solid content of the composite spinning solution in the S2 step is 2%-8%.

5. A nitride-doped graphene modified aramid III fiber acylchlorinated, characterized by, Prepared by the preparation method of any one of claims 1-4.

6. The acyl chloride modified nitrogen-doped graphene modified aramid III fiber according to claim 5, characterized in that, The acyl chloride doped nitrogen graphene modified aramid III fiber has a breaking strength of 29-35cN / dtex, an elastic modulus of 800-1200cN / dtex, and an elongation at break of 3.3-5.7%.

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