Polyurethane reinforced aramid fiber composite fiber with self-repairing capability and preparation method of polyurethane reinforced aramid fiber composite fiber

Abstract

The invention provides a polyurethane reinforced aramid composite fiber with self-repairing capability and a preparation method thereof, and belongs to the technical field of composite reinforced materials. The preparation method comprises the following steps: dissociating aramid fibers in DMSO (Dimethylsulfoxide) to form an aramid nanofiber (ANF) suspension, forming a dispersion liquid from polyurethane (WPU) in the DMSO, mixing the suspension and the dispersion liquid according to a specific ratio, and carrying out wet spinning to obtain the polyurethane reinforced aramid composite fiber with self-repairing capability. Wherein a'thread 'structure is formed on the surface of the composite fiber due to staggered hydrogen bonds, and the compact structure greatly improves the mechanical property of the composite fiber; o atoms with Lewis alkalinity in the solvent DMSO are firstly combined with Cl atoms on isocyanate groups in polyurethane to form a polarized intermediate DMSOCl, and the polarized intermediate DMSOCl can further react with active groups on aramid fibers, so that chemical grafting is realized. The composite fiber has excellent self-healing performance, and the broken part can be autonomously healed at 60-120 DEG C.

Description

Technical Field

[0001] The present invention relates to the technical field of composite reinforcement materials, and in particular to a polyurethane-reinforced aramid composite fiber with self-repairing ability and a preparation method thereof. Background Art

[0002] Traditional fibers, due to their single performance, are no longer able to meet the needs of diverse applications. Differentiated functional fibers are fibers with specialized properties (such as flame retardancy, antibacterial properties, antistatic properties, and far-infrared properties). These fibers are produced through modification and compounding techniques to meet the needs of diverse applications.

[0003] Aramid fiber has good mechanical properties. To further improve the strength of aramid fiber, it is usually combined with other materials. However, it is often difficult to achieve a balance between the flexibility and strength of the composite fiber, and the performance of the composite material is single, which cannot meet the needs of multiple scenarios. Summary of the Invention

[0004] In view of the technical problems existing in the background technology, the present application provides a polyurethane reinforced aramid composite fiber with self-repairing ability and a preparation method thereof, aiming to solve the problems of the existing electromagnetic shielding composite film that it is difficult to balance the electromagnetic shielding effect and mechanical properties, the filler is difficult to disperse evenly, and the conductive network is discontinuous.

[0005] In a first aspect, the present application provides a method for preparing a polyurethane-reinforced aramid composite fiber with self-repairing ability, characterized by comprising the following steps: S1. Aramid fiber was added to DMSO, followed by KOH and deionized water, and stirred to obtain an ANF dispersion; S2. WPU was added to DMSO and stirred to obtain a WPU dispersion; S3. The ANF dispersion and the WPU dispersion are mixed and stirred to obtain a spinning solution; S4. The spinning solution is wet-spinned to obtain polyurethane-reinforced aramid composite fibers.

[0006] In the technical solution of the embodiment of the present application, aramid fibers are dissociated in DMSO to form an aramid nanofiber suspension, polyurethane is formed into a dispersion in DMSO, and the above suspension and dispersion are then mixed in a specific ratio. Subsequently, wet spinning is used to obtain a polyurethane-reinforced aramid composite fiber with self-healing ability. Among them, the surface of the composite fiber forms a "threaded" structure due to staggered hydrogen bonds. This compact structure greatly improves the mechanical properties of the composite fiber. The Lewis-basic O atoms in the solvent DMSO first combine with the Cl atoms on the isocyanate group in the polyurethane to form a polarized intermediate DMSOCl⁺, which can further react with the active groups on the aramid, thereby achieving chemical grafting. In addition, the same solvent also improves the interfacial compatibility of the material, making the composite fiber more uniform and stable.

[0007] In some embodiments, in step S3, the mass ratio of the ANF dispersion to the WPU dispersion is 1:3-5.

[0008] In this embodiment, ANF dispersion and WPU dispersion are mixed in a specific ratio so that they can fully react and graft, so that the final composite membrane has flexibility while having excellent strength and good self-repairing ability.

[0009] In some embodiments, in step S1, the concentration of the ANF dispersion is 10-15 wt%.

[0010] In this example, ANF is dispersed in DMSO, where it undergoes a deprotonation reaction on the aramid fibers. DMSO, as a solvent, removes hydrogen atoms from the amino groups of the aramid fibers, giving them a negative charge. This process weakens the hydrogen bonds between the fiber's molecular chains, causing the fibers to gradually break down into nanoscale fibers.

[0011] In some embodiments, in step S4, the temperature of the wet spinning is 40-60°C.

[0012] In this embodiment, the structures of aramid fiber and polyurethane have certain similarities. At 40~60℃, the wettability of both is improved. Aramid fiber and polyurethane have good wettability and can form a fiber with a "threaded" structure through staggered hydrogen bonds. This structure improves the structural tightness of the composite fiber and enhances the strength of the fiber.

[0013] In some embodiments, in step S1, the volume ratio of the DMSO to the deionized water is 10:1.

[0014] In this example, DMSO, a highly polar aprotic solvent, deprotonates the ANF, thereby imparting a negative charge to the fiber. Upon addition of water, the water molecules, acting as proton donors, react with the negative charges on the ANF surface, allowing the fiber to recharge some or all of its protons.

[0015] In some embodiments, in step S2, the concentration of the WPU dispersion is 30-35 wt%.

[0016] In this embodiment, by dispersing WPU in DMSO, the Lewis-basic O atom first combines with the Cl atom on the isocyanate group in PU to form a polarized intermediate DMSOCl⁺, which has much higher reactivity than the isocyanate group and can further react with the active groups on the aramid, thereby achieving chemical grafting.

[0017] In some embodiments, in step S1, the stirring temperature is room temperature, the stirring time is 5.5-6.5 h, and the stirring rate is 300 rpm.

[0018] In this embodiment, aramid fibers are stirred in an alkaline solution to obtain an aramid nanofiber dispersion.

[0019] In some embodiments, in step S2, the stirring temperature is room temperature, the stirring time is 1.5 to 2.5 hours, and the stirring rate is 300 rpm.

[0020] In this embodiment, WPU and DMSO solvent are fully mixed by stirring to facilitate the subsequent grafting reaction.

[0021] In some embodiments, in step S3, the stirring temperature is room temperature, the stirring time is 2-3 hours, and the stirring rate is 300 rpm.

[0022] In this embodiment, the ANF dispersion and the WPU dispersion were fully mixed by stirring.

[0023] In the second aspect, the present application provides a polyurethane reinforced aramid composite fiber with self-repairing ability, which is characterized in that it is prepared by the above-mentioned preparation method of the polyurethane reinforced aramid composite fiber with self-repairing ability; the polyurethane reinforced aramid composite fiber with self-repairing ability has a fracture self-healing property at 60~120°C; the tensile strength of the polyurethane reinforced aramid composite fiber with self-repairing ability is 9~13Mpa.

[0024] In the technical solution of the present embodiment, high-strength aramid nanofibers and WPU are dispersed in a DMSO solvent, then blended to form a spinning solution. A self-healing polyurethane-reinforced aramid composite fiber is produced by wet spinning. The combination of hydrogen and ionic bonds between the polyurethane and aramid fibers, as well as the formation of a "threaded" structure, achieved through the chemical medium formed by the same solvent, DMSO, gives the composite fiber excellent self-healing and tensile properties.

[0025] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0027] Figure 1 These are the surface SEM images and cross-sectional SEM images of the polyurethane reinforced aramid composite fiber prepared in Example 1.

[0028] Figure 2 This is a self-healing image of the polyurethane reinforced aramid composite fiber prepared in Example 1 under an optical microscope.

[0029] Figure 3 These are the stress-strain diagrams of the polyurethane reinforced aramid composite fiber prepared in Example 1, as is, after one and two stretching fractures and then healing.

[0030] Figure 4 4 and 5 and comparative examples 3 and 4.

[0031] Figure 5 Surface SEM images of the polyurethane reinforced aramid composite fibers prepared in Comparative Examples 3 and 4. DETAILED DESCRIPTION

[0032] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms "including" and "having" and any variations thereof used herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0034] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] To address the problems of existing aramid-reinforced fibers, which suffer from a single function and struggle to balance flexibility and strength, this application provides a self-healing polyurethane-reinforced aramid composite fiber and its preparation method. Aramid fibers are dissociated in DMSO to form an aramid nanofiber (ANF) suspension, polyurethane (WPU) is dispersed in DMSO to form a dispersion, and the two suspensions and dispersions are mixed in a specific ratio. The self-healing polyurethane-reinforced aramid composite fibers are then wet-spun. Polyurethane contains numerous hydroxyl groups and carbamate bonds, which react with the amide bonds in aramid to form esterification reactions. The carbamate and amide groups can also interact through hydrogen bonding. Furthermore, the structures of the two fibers are similar. At temperatures between 40 and 60°C, the wettability of both fibers is enhanced, with the aramid fibers exhibiting better wettability. These fibers can form a "threaded" structure through staggered hydrogen bonding, enhancing the structural tightness and strength of the composite fibers. The solvent used for both is DMSO, in which the Lewis-basic O atom first combines with the Cl atom of the isocyanate group to form a polarized intermediate, DMSOCl⁺. This polarized intermediate is much more reactive than the isocyanate group and can further react with the active groups on the aramid, thereby achieving chemical grafting. Furthermore, the use of the same solvent improves the interfacial compatibility of the materials, making the composite fiber more uniform and stable. The composite fiber exhibits excellent self-healing properties, capable of autonomously healing broken sections at temperatures between 60 and 120°C. It also exhibits excellent mechanical properties, with a tensile strength of 9 to 13 MPa.

[0036] The present application provides a method for preparing a polyurethane-reinforced aramid composite fiber with self-repairing ability, which is characterized by comprising the following steps: S1. Aramid fiber was added to DMSO, followed by KOH and deionized water, and stirred to obtain an ANF dispersion; S2. WPU was added to DMSO and stirred to obtain a WPU dispersion; S3. The ANF dispersion and the WPU dispersion are mixed and stirred to obtain a spinning solution; S4. The spinning solution is wet-spinned to obtain polyurethane-reinforced aramid composite fibers.

[0037] In the technical solution of the embodiment of the present application, aramid fibers are dissociated in DMSO to form an aramid nanofiber suspension, polyurethane is formed into a dispersion in DMSO, and the above suspension and dispersion are then mixed in a specific ratio. Subsequently, wet spinning is used to obtain a polyurethane-reinforced aramid composite fiber with self-healing ability. Among them, the surface of the composite fiber forms a "threaded" structure due to staggered hydrogen bonds. This compact structure greatly improves the mechanical properties of the composite fiber. The Lewis-basic O atoms in the solvent DMSO first combine with the Cl atoms on the isocyanate group in the polyurethane to form a polarized intermediate DMSOCl⁺, which can further react with the active groups on the aramid, thereby achieving chemical grafting. In addition, the same solvent also improves the interfacial compatibility of the material, making the composite fiber more uniform and stable.

[0038] Furthermore, in some embodiments, in step S3, the mass ratio of the ANF dispersion to the WPU dispersion is 1:3-5.

[0039] In the technical solution of the embodiment of the present application, ANF dispersion and WPU dispersion are mixed in a specific ratio so that the two can fully react and graft, so that the final composite film has flexibility while having excellent strength and good self-repairing ability.

[0040] Furthermore, in some embodiments, in step S1, the concentration of the ANF dispersion is 10-15 wt%.

[0041] In the technical solution of the present embodiment, ANF is dispersed in DMSO, where the aramid fibers undergo a deprotonation reaction. DMSO, as a solvent, removes hydrogen atoms from the amino groups of the aramid fibers, giving them a negative charge. This process weakens the hydrogen bonds between the fiber's molecular chains, causing the fibers to gradually break down into nanoscale fibers.

[0042] Furthermore, in some embodiments, in step S4, the temperature of the wet spinning is 40-60°C.

[0043] In the technical solution of the embodiment of the present application, the structures of aramid fiber and polyurethane have certain similarities. At 40~60℃, the wettability of both is improved. Aramid fiber and polyurethane have good wettability and can form a fiber with a "threaded" structure through staggered hydrogen bonds. This structure improves the structural tightness of the composite fiber and enhances the strength of the fiber.

[0044] Furthermore, in some embodiments, in step S1, the volume ratio of the DMSO to the deionized water is 10:1.

[0045] In the technical solution of the embodiments of this application, DMSO is a highly polar aprotic solvent that deprotonates the ANF, thereby imparting a negative charge to the fiber. Upon addition of water, the water molecules, acting as proton donors, react with the negative charges on the ANF surface, allowing the fiber to re-charge some or all of its protons.

[0046] Furthermore, in some embodiments, in step S2, the concentration of the WPU dispersion is 30-35 wt %.

[0047] In the technical solution of the embodiment of the present application, by dispersing WPU in DMSO, the O atom with Lewis basicity first combines with the Cl atom on the isocyanate group in PU to form a polarized intermediate DMSOCl⁺, which has much higher reactivity than the isocyanate group and can further react with the active group on the aramid, thereby achieving chemical grafting.

[0048] Furthermore, in some embodiments, in step S1, the stirring temperature is room temperature, the stirring time is 5.5-6.5 h, and the stirring rate is 300 rpm.

[0049] In the technical solution of the embodiment of the present application, aramid fibers are stirred in an alkaline solution to obtain an aramid nanofiber dispersion.

[0050] Furthermore, in some embodiments, in step S2, the stirring temperature is room temperature, the stirring time is 1.5 to 2.5 hours, and the stirring rate is 300 rpm.

[0051] In the technical solution of the embodiment of the present application, WPU and DMSO solvent are fully mixed by stirring to facilitate the subsequent grafting reaction.

[0052] Furthermore, in some embodiments, in step S3, the stirring temperature is room temperature, the stirring time is 2-3 h, and the stirring rate is 300 rpm.

[0053] In the technical solution of the embodiment of the present application, the ANF dispersion and the WPU dispersion are fully mixed by stirring.

[0054] In the second aspect, an embodiment of the present application provides a polyurethane reinforced aramid composite fiber with self-repairing ability, which is characterized in that it is prepared by the above-mentioned preparation method of the polyurethane reinforced aramid composite fiber with self-repairing ability; the polyurethane reinforced aramid composite fiber with self-repairing ability has a fracture self-healing property at 60~120°C; the tensile strength of the polyurethane reinforced aramid composite fiber with self-repairing ability is 9~13Mpa.

[0055] In the technical solution of the present embodiment, high-strength aramid nanofibers and WPU are dispersed in a DMSO solvent, then blended to form a spinning solution. A self-healing polyurethane-reinforced aramid composite fiber is produced by wet spinning. The combination of hydrogen and ionic bonds between the polyurethane and aramid fibers, as well as the formation of a "threaded" structure, achieved through the chemical medium formed by the same solvent, DMSO, gives the composite fiber excellent self-healing and tensile properties.

[0056] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0057] Example 1 This embodiment provides a method for preparing a polyurethane-reinforced aramid composite fiber with self-repairing ability, which specifically includes the following steps: (1) Weigh 1 g of aramid fiber and add it to 100 mL of DMSO. Then add 1.5 g of KOH and 4 mL of deionized water. Stir at 300 rpm for 6 h at room temperature to obtain a 1 wt% ANF dispersion.

[0058] (2) Weigh 1.88 g of WPU, add it to 20 mL of DMSO, and stir at 300 rpm for 2 h at room temperature to obtain a 1 wt% WPU dispersion.

[0059] (3) The above-mentioned ANF dispersion and WPU dispersion were mixed in a mass ratio of 1:3 and stirred at 300 rpm for 2 h at room temperature to obtain a spinning solution.

[0060] (4) The spinning solution is wet-spun at 50°C to obtain polyurethane-reinforced aramid composite fibers.

[0061] The surface SEM images and cross-sectional SEM images of the polyurethane reinforced aramid composite fibers prepared in this embodiment are as follows: Figure 1 shown.

[0062] Depend onFigure 1 It can be seen from the SEM image in that the surface of the prepared polyurethane reinforced aramid composite fiber has a "threaded" structure.

[0063] Figure 2 This is a self-healing image of the polyurethane reinforced aramid composite fiber prepared in this example under an optical microscope.

[0064] Depend on Figure 2 It can be seen that the composite fiber begins to heal at 60°C and is almost completely healed at 120°C.

[0065] Figure 3 These are the stress-strain diagrams of the polyurethane reinforced aramid composite fiber prepared in this example, as is, after one and two stretching fractures and then healing.

[0066] Depend on Figure 3 It can be seen that the tensile strength of the composite fiber does not decrease significantly after being broken once or twice.

[0067] Examples 2-3 and Comparative Examples 1-2 Examples 2-3 and Comparative Examples 3-4 respectively provide a method for preparing a polyurethane-reinforced aramid composite fiber with self-repairing ability. Compared with Example 1, the difference is that the mass ratio of the ANF dispersion and the WPU dispersion is different, as shown in Table 1. The other steps are roughly the same as those in Example 1 and are not repeated here.

[0068] Table 1 Mass ratio and tensile strength at break of ANF dispersion and WPU dispersion in Examples 2-3 and Comparative Examples 1-2 Examples 4-5 and Comparative Examples 3-4 Examples 4-5 and Comparative Examples 3-4 respectively provide a method for preparing a polyurethane-reinforced aramid composite fiber with self-repairing ability. Compared with Example 1, the difference is that the wet spinning temperature is different, as shown in Table 2. The other steps are roughly the same as those in Example 1 and are not repeated here.

[0069] Table 2 Temperature and tensile strength of wet spinning in Examples 4-5 and Comparative Examples 3-4 The tensile fracture properties of the polyurethane reinforced aramid composite fibers prepared in Examples 2 to 5 and Comparative Examples 1 to 4 were tested, and the results are shown in Tables 1, 2 and Figure 4 shown.

[0070] The surface SEM images of the polyurethane reinforced aramid composite fibers prepared in Comparative Examples 3 and 4 are as follows: Figure 5 shown.

[0071] From the results in Table 1, it can be seen that the tensile properties of the composite fiber material are best when the mass ratio of ANF dispersion to WPU dispersion is 1:3~5. When the amount of WPU added is too much, the tensile properties of the composite fiber material will deteriorate. Because WPU is very flexible, when its content is too high, the fiber material will be too soft as a whole, resulting in a decrease in tensile strength. The fiber is more likely to deform or even break when subjected to force, and it is impossible to maintain good mechanical properties. When the amount of WPU added is too little, the tensile properties of the composite fiber material will also be affected. Since WPU plays a certain toughening role in the composite material, when its content is insufficient, the flexibility of the fiber material is insufficient, the brittleness increases, and it is more likely to break during the stretching process, and it is impossible to achieve the best tensile properties. From Table 2 and Figure 5 It can be seen that it is difficult for composite fibers to form a spiral structure under high and low temperature conditions. At high temperatures, the molecular motion is too violent, the chemical reaction is too fast and the solvent properties are unstable; at low temperatures, the molecular motion is restricted, the chemical reaction is too slow and the solvent viscosity is too high. The wettability of the composite fibers is reduced at low temperatures. Aramid fibers and polyurethane do not have good wettability and cannot be combined to form fibers with a "threaded" structure.

[0072] In summary, the present application provides a polyurethane-reinforced aramid composite fiber with self-healing capabilities and a preparation method thereof. In the present application, aramid fibers are dissociated in DMSO into an aramid nanofiber (ANF) suspension, polyurethane (WPU) is formed into a dispersion in DMSO, the suspension and dispersion are then mixed in a specific ratio, and then wet-spinning is performed to obtain a polyurethane-reinforced aramid composite fiber with self-healing capabilities. Polyurethane contains a large number of hydroxyl groups and carbamate bonds, while the amide bonds in aramid can undergo esterification reactions with them, and the carbamate and amide groups can also interact through hydrogen bonds. Furthermore, the structures of the two fibers have certain similarities. At 40-60°C, the wettability of the two fibers is improved. Aramid fibers and polyurethane have better wettability and can combine through staggered hydrogen bonds to form a fiber with a "threaded" structure. This structure improves the structural tightness of the composite fiber and enhances the strength of the fiber. The solvent used for both is DMSO, in which the Lewis-basic O atom first combines with the Cl atom of the isocyanate group to form a polarized intermediate, DMSOCl⁺. This polarized intermediate is much more reactive than the isocyanate group and can further react with the active groups on the aramid, thereby achieving chemical grafting. Furthermore, the use of the same solvent improves the interfacial compatibility of the materials, making the composite fiber more uniform and stable. The composite fiber exhibits excellent self-healing properties, capable of autonomously healing broken sections at temperatures between 60 and 120°C. It also exhibits excellent mechanical properties, with a tensile strength of 9 to 13 MPa.

[0073] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a polyurethane-reinforced aramid composite fiber with self-repairing ability, characterized in that: The following steps are involved: S1. Aramid fiber was added to DMSO, followed by KOH and deionized water, and stirred to obtain an ANF dispersion; S2. WPU was added to DMSO and stirred to obtain a WPU dispersion; S3. The ANF dispersion and the WPU dispersion are mixed and stirred to obtain a spinning solution; S4. The spinning solution is wet-spinned to obtain polyurethane-reinforced aramid composite fibers.

2. The method for preparing the polyurethane-reinforced aramid composite fiber with self-repairing ability according to claim 1, characterized in that: In step S3, the mass ratio of the ANF dispersion to the WPU dispersion is 1:3-5.

3. The method for preparing the polyurethane-reinforced aramid composite fiber with self-repairing ability according to claim 1, characterized in that: In step S1, the concentration of the ANF dispersion is 10-15 wt%.

4. The method for preparing the polyurethane-reinforced aramid composite fiber with self-repairing ability according to claim 1, characterized in that: In step S4, the temperature of the wet spinning is 40-60°C.

5. The method for preparing the polyurethane-reinforced aramid composite fiber with self-repairing ability according to claim 1, characterized in that: In step S1, the volume ratio of the DMSO to the deionized water is 10:

1.

6. The method for preparing the polyurethane-reinforced aramid composite fiber with self-repairing ability according to claim 1, characterized in that: In step S2, the concentration of the WPU dispersion is 30-35 wt%.

7. The method for preparing the polyurethane-reinforced aramid composite fiber with self-repairing ability according to claim 1, characterized in that: In step S1, the stirring temperature is room temperature, the stirring time is 5.5-6.5 h, and the stirring rate is 300 rpm.

8. The method for preparing the polyurethane-reinforced aramid composite fiber with self-repairing ability according to claim 1, characterized in that: In step S2, the stirring temperature is room temperature, the stirring time is 1.5 to 2.5 hours, and the stirring rate is 300 rpm.

9. The method for preparing the polyurethane-reinforced aramid composite fiber with self-repairing ability according to claim 1, characterized in that: In step S3, the stirring temperature is room temperature, the stirring time is 2 to 3 hours, and the stirring rate is 300 rpm.

10. A polyurethane reinforced aramid composite fiber with self-repairing ability, characterized in that: The self-repairing polyurethane reinforced aramid composite fiber is prepared by the preparation method of any one of claims 1 to 8; the self-repairing polyurethane reinforced aramid composite fiber has fracture self-healing performance at 60~120°C; the tensile strength of the self-repairing polyurethane reinforced aramid composite fiber is 9~13Mpa.

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