CN117106295A - A modified polyimide short fiber/thermoplastic polyurethane composite material and its preparation method - Google Patents

Abstract

The invention discloses a modified polyimide short fiber/thermoplastic polyurethane composite material and a preparation method thereof. The composite material is prepared from raw materials including the following components by weight: 100 parts by weight of thermoplastic polyurethane; modified polyimide Amine fiber 0.5-5 parts by weight; antioxidant 0.1-0.5 parts by weight. The modified polyimide short fiber of the present invention can improve the mechanical properties and thermal coupling properties of thermoplastic polyurethane. The mechanical properties of the composite materials prepared by the present invention and the modulus of the materials at high temperatures are significantly improved. When a small amount of modified polyimide fiber is added to thermoplastic polyurethane, its performance is greatly improved, which also saves production costs and expands the application scope of polyurethane composite materials. The preparation method of the invention has simple technological process, lower production cost and wider application range.

Description

A modified polyimide short fiber/thermoplastic polyurethane composite material and its preparation method

Technical field

The present invention relates to the technical field of composite materials, and more specifically, to a modified polyimide short fiber/thermoplastic polyurethane composite material and a preparation method thereof.

Background technique

Polyurethane elastomer (PU) consists of two thermodynamically incompatible phases, forming a microphase separation structure in which hard segments and soft segments are alternately arranged to form hard domains and soft domains. It is precisely because of the special two-phase coexistence and separation structure of polyurethane that polyurethane elastomer is a special polymer material with properties between plastic and rubber, which gives thermoplastic polyurethane repeatable processing properties and excellent mechanical properties. A wide range of applications have been achieved in various fields. However, because its cross-linked network structure is produced by physical effects, its low modulus and poor dimensional stability at high temperatures limit its application.

In order to improve the comprehensive performance of polyurethane, high-modulus fibers are usually used to reinforce polyurethane materials to improve the modulus and thermal coupling properties of polyurethane. Previous research on fiber-reinforced polyurethane, such as Chinese patent CN108673984 A, discloses a resin-based composite material using modified polyimide fiber as reinforcement. The mass proportion of polyimide fiber is 60% to 90%, and the mass proportion of resin matrix is 10% to 40%. It is compounded with matrix resin through a specific composite process to prepare a bulletproof composite material. This work uses a large amount of polyimide long fibers and a resin matrix to form a composite material. While improving the rigidity of the composite material, it also sacrifices elasticity and cannot be applied in the field of elastomers. In addition, the cost of polyimide fiber is relatively high. It is expensive, so its application range is narrow and can only be used in military and high-end civilian fields.

Contents of the invention

In order to solve the problems existing in the prior art, the present invention provides a modified polyimide short fiber/thermoplastic polyurethane composite material and a preparation method thereof. The modified polyimide short fiber of the present invention can improve the mechanical properties and thermal coupling properties of thermoplastic polyurethane. The mechanical properties of the composite materials prepared by the present invention and the modulus of the materials at high temperatures are significantly improved. When a small amount of modified polyimide fiber is added to thermoplastic polyurethane, its performance is greatly improved, which also saves production costs and expands the application scope of polyurethane composite materials. The preparation method of the invention has simple technological process, lower production cost and wider application range.

One of the objects of the present invention is to provide a modified polyimide short fiber/thermoplastic polyurethane composite material, which is prepared from raw materials including the following components by weight:

Thermoplastic polyurethane 100 parts by weight;

Modified polyimide fiber 0.5-5 parts by weight;

Antioxidant 0.1-0.5 parts by weight.

Preferably, the raw materials are expressed in parts by weight:

Thermoplastic polyurethane 100 parts by weight;

Modified polyimide fiber 0.5-3 parts by weight;

Antioxidant 0.1-0.3 parts by weight.

Preferably, the modified polyimide fiber is obtained by subjecting the polyimide fiber to ultrasonic treatment in an alkali solution and protonation treatment in an acid solution. Through pre-treatment with alkaline solution, the polar group -COOH can be introduced on the surface of polyimide, and the surface of polyimide fiber can also be etched to increase the mechanical interlocking ability of polyimide fiber and polyurethane, thus Effectively increase the interface performance between polyimide fiber and polyurethane.

Preferably, the modified polyimide fiber is prepared by a method including the following steps:

(1) Ultrasonic treatment of polyimide fiber in alkaline solution;

The alkali solution is potassium hydroxide solution or sodium hydroxide solution, and the ultrasonic treatment time is 10-60 minutes;

(2) The ultrasonic-treated polyimide fiber is placed in an acid solution for protonation treatment to remove OH ^- in the solution;

The acid solution is an acetic acid solution, and the treatment time is 10-20 minutes.

Preferably, the concentration of the alkali solution in step (1) is 0.5-2mol/L; the concentration of the acid solution in step (2) is 0.05-0.3mol/L.

Preferably, after ultrasonic treatment in the alkali solution of step (1) and protonation treatment in the acid solution of step (2), the polyimide fiber is dried at a temperature of 90-110°C for 8-12 hours to obtain the resultant fiber. Modified polyimide fiber.

Specifically, the following solutions can be adopted:

Prepare a KOH solution with a concentration of 1 mol·L ^-1 , add the polyimide fiber that has been cleaned and dried at room temperature, and react with ultrasonic treatment and machine head stirring for 10-60 minutes respectively. After the treatment is completed, take out the fiber. And wash with deionized water 4-5 times. Prepare an acetic acid solution of 0.1 mol·L ^-1 , protonate the fiber at room temperature for 10-20 minutes, wash it with deionized water 4-5 times after the reaction, and bake it in a vacuum oven at a temperature of 90-110°C for 8 -12h, the modified polyimide fiber is obtained for later use.

Preferably, the modified polyimide fiber is a short fiber with a length of 1-15 mm. Among commonly used fibers, glass fiber and carbon fiber are brittle and have poor impact resistance. Aramid fiber has poor aging performance and is not resistant to ultraviolet radiation. Polyimide fiber has excellent heat resistance, mechanical properties, solvent resistance and resistance to UV radiation. Low temperature performance, excellent comprehensive performance. Using high-modulus polyimide fiber to reinforce polyurethane materials can improve the modulus and thermal coupling performance of polyurethane.

The antioxidant can be antioxidants commonly used in this field, such as antioxidant 1010, antioxidant 2103, antioxidant 1135, etc.

Conventional additives can also be added to the formula of the present invention according to the actual situation, such as anti-ozone agents, anti-flex cracking agents, light stabilizers, ultraviolet absorbers, physical antioxidants, etc., and their dosages are conventional dosages. Technical personnel It can be added according to the actual situation.

The second object of the present invention is to provide a method for preparing modified polyimide short fiber/thermoplastic polyurethane composite material. The method includes: melting and blending the components according to the dosage to prepare the modified polyimide short fiber/thermoplastic polyurethane composite material. Polyimide short fiber/thermoplastic polyurethane composite.

Preferably, the melting temperature is 190-210°C and the melting time is 3-5 minutes.

Preferably, the blending temperature is 190-210°C, the rotation speed is 50-80 rpm, and the blending time is 4-8 minutes.

Specifically, the following solutions can be adopted:

Dry the thermoplastic polyurethane in an oven at 80-100°C for 8-12 hours. Add 100 parts by weight of the vacuum-dried thermoplastic polyurethane to an internal mixer at 190-210°C. After melting for 3-5 minutes, add 0.5-5 parts by weight. parts of the above-mentioned modified polyimide fiber and 0.1-0.5 parts by weight of antioxidant, and then mixed at a temperature of 190-210°C and a rotation speed of 50-80 rpm for 4-8 minutes, and then taken out to obtain the modified polyimide short fiber. Fiber/thermoplastic polyurethane composite.

Since polyimide fiber has good resistance to high temperatures and solvents, is resistant to oxidation at high temperatures, and has good overall properties, the invention modified the polyimide short fiber with an alkali solution to increase the number of polyimide fibers and The interfacial adhesion between polyurethanes can be improved by adding a small amount of chopped polyimide fibers treated with alkali solution to improve the mechanical properties and thermal coupling properties of thermoplastic polyurethane and expand the application range of polyurethane. The mechanical properties of the composite materials prepared by the present invention and the modulus of the materials at high temperatures are significantly improved. When a small amount of modified polyimide fiber is added to thermoplastic polyurethane, its performance is greatly improved, which also saves production costs and expands the application scope of polyurethane composite materials. The preparation method of the present invention has simple process flow, lower production cost and wider application range. The composite material of the present invention can be used in fields such as tires and shock-absorbing pads.

Description of drawings

Figure 1 is a stress-strain curve diagram of Examples 1-9 and Comparative Examples 1-2;

Figure 2 is a dynamic thermomechanical analysis (DMA) storage modulus diagram of Examples 1-4 and Comparative Examples 1-2.

Detailed ways

The present invention will be described in detail below with reference to specific drawings and examples. It is necessary to point out here that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of the present invention. Those skilled in the art will refer to this SUMMARY OF THE INVENTION Some non-essential improvements and adjustments made to the present invention still fall within the protection scope of the present invention.

The raw materials used in the examples and comparative examples of the present invention are all commercially available products. The specific raw material information is as follows in Table 1:

Table 1

product name Specification factory polyimide fiber S0T-2D Jiangsu Xiannuo New Material Technology Co., Ltd. Antioxidant 1010 99.5% Beijing Additive Additives Research Institute polyurethane TPUE95 Yantai Meirui New Materials Co., Ltd. Potassium hydroxide AR Aladdin Acetic acid 99% Aladdin

Example 1

Prepare a KOH solution with a concentration of 1 mol·L ^-1 , add the polyimide fiber that has been cleaned and dried at room temperature, and react with ultrasonic treatment and machine head stirring for 45 minutes respectively. After the treatment is completed, take out the fiber and use deionization Rinse with water 4-5 times. Prepare an acetic acid solution of 0.1 mol·L ^-1 , protonate the fiber at room temperature for 10 minutes, wash it with deionized water 4-5 times after the reaction, and bake it in a vacuum oven at 100°C for 10 hours to obtain the modified polyethylene. Imide fiber is available for use, and the length of modified polyimide fiber is 3-5mm.

Dry the thermoplastic polyurethane in an oven at 100°C for 12 hours, dry the above-mentioned modified polyimide fiber in a vacuum oven at 120°C for 12 hours, and add 100 parts by weight of the vacuum-dried polyurethane to the internal kneading oven at 190°C. In the machine, set the rotation speed to 60 rpm. After melting for 3 minutes, add 0.5 parts by weight of modified polyimide fiber and 0.25 parts by weight of antioxidant 1010. Then, after kneading for 4 minutes, take it out to obtain the modified polyimide short fiber/thermoplastic polyurethane composite material. Take 20g of the composite material prepared by melt blending, place it in a 1mm mold, and then place it in a vacuum flat vulcanizer. The temperature is set to 200°C. It is preheated for 5 minutes, then hot pressed for 8 minutes, and cold pressed for 5 minutes. Take out the sample and leave it for 3-5 days for subsequent testing.

Example 2

Prepare a KOH solution with a concentration of 1 mol·L ^-1 , add the polyimide fiber that has been cleaned and dried at room temperature, and react with ultrasonic treatment and machine head stirring for 45 minutes respectively. After the treatment is completed, take out the fiber and use deionization Rinse with water 4-5 times. Prepare an acetic acid solution of 0.1 mol·L ^-1 . Protonate the fiber at room temperature for 10 minutes. After the reaction, wash it with deionized water 4-5 times. Dry the fiber in a vacuum oven at 100°C for 10 hours. , the modified polyimide fiber is obtained for use, and the length of the modified polyimide fiber is 3-5mm.

Dry the thermoplastic polyurethane in an oven at 100°C for 12 hours, dry the above-mentioned modified polyimide fiber in a vacuum oven at 120°C for 12 hours, and add 100 parts by weight of the vacuum-dried polyurethane to the internal kneading oven at 190°C. In the machine, set the rotation speed to 60 rpm. After melting for 3 minutes, add 1 part by weight of modified polyimide fiber and 0.25 part by weight of antioxidant 1010. Then, after kneading for 4 minutes, take it out to obtain the modified polyimide short fiber/thermoplastic polyurethane composite material. Take 20g of the composite material prepared by melt blending, place it in a 1mm mold, and then place it in a vacuum flat vulcanizer. The temperature is set to 200°C. It is preheated for 5 minutes, then hot pressed for 8 minutes, and cold pressed for 5 minutes. Take out the sample and leave it for 3-5 days for subsequent testing.

Example 3

Prepare a KOH solution with a concentration of 1 mol·L ^-1 , add the polyimide fiber that has been cleaned and dried at room temperature, and react with ultrasonic treatment and machine head stirring for 45 minutes respectively. After the treatment is completed, take out the fiber and use deionization Rinse with water 4-5 times. Prepare an acetic acid solution of 0.1 mol·L ^-1 . Protonate the fiber at room temperature for 10 minutes. After the reaction, wash it with deionized water 4-5 times. Dry the fiber in a vacuum oven at 100°C for 10 hours. , the modified polyimide fiber is obtained for use, and the length of the modified polyimide fiber is 3-5mm.

Dry the thermoplastic polyurethane in an oven at 100°C for 12 hours, dry the above-mentioned modified polyimide fiber in a vacuum oven at 120°C for 12 hours, and add 100 parts by weight of the vacuum-dried polyurethane to the internal kneading oven at 190°C. In the machine, set the rotation speed to 60 rpm, add 2 parts by weight of modified polyimide fiber and 0.25 parts by weight of antioxidant 1010 after melting for 3 minutes. Then, after kneading for 4 minutes, take it out to obtain the modified polyimide short fiber/thermoplastic polyurethane composite material. Take 20g of the composite material prepared by melt blending, place it in a 1mm mold, and then place it in a vacuum flat vulcanizer. The temperature is set to 200°C. It is preheated for 5 minutes, then hot pressed for 8 minutes, and cold pressed for 5 minutes. Take out the sample and leave it for 3-5 days for subsequent testing.

Example 4

Prepare a KOH solution with a concentration of 1 mol·L ^-1 , add the polyimide fiber that has been cleaned and dried at room temperature, and react with ultrasonic treatment and machine head stirring for 45 minutes respectively. After the treatment is completed, take out the fiber and use deionization Rinse with water 4-5 times. Prepare an acetic acid solution of 0.1 mol·L ^-1 . Protonate the fiber at room temperature for 10 minutes. After the reaction, wash it with deionized water 4-5 times. Dry the fiber in a vacuum oven at 100°C for 10 hours. , the modified polyimide fiber is obtained for use, and the length of the modified polyimide fiber is 3-5mm.

Dry the thermoplastic polyurethane in an oven at 100°C for 12 hours, dry the above-mentioned modified polyimide fiber in a vacuum oven at 120°C for 12 hours, and add 100 parts by weight of the vacuum-dried polyurethane to the internal kneading oven at 190°C. In the machine, set the rotation speed to 60 rpm. After melting for 3 minutes, add 3 parts by weight of modified polyimide fiber and 0.25 parts by weight of antioxidant 1010. Then, after kneading for 4 minutes, take it out to obtain the modified polyimide short fiber/thermoplastic polyurethane composite material. Take 20g of the composite material prepared by melt blending, place it in a 1mm mold, and then place it in a vacuum flat vulcanizer. The temperature is set to 200°C. It is preheated for 5 minutes, then hot pressed for 8 minutes, and cold pressed for 5 minutes. Take out the sample and leave it for 3-5 days for subsequent testing.

Example 5

Prepare a KOH solution with a concentration of 0.5 mol·L ^-1 , add the polyimide fiber that has been cleaned and dried at room temperature, and react with ultrasonic treatment and machine head stirring for 45 minutes respectively. After the treatment is completed, take out the fiber and use it. Wash with ionized water 4-5 times. Prepare an acetic acid solution of 0.1 mol·L ^-1 . Protonate the fiber at room temperature for 10 minutes. After the reaction, wash it with deionized water 4-5 times. Dry the fiber in a vacuum oven at 100°C for 10 hours. , the modified polyimide fiber is obtained for use, and the length of the modified polyimide fiber is 3-5mm.

Dry the thermoplastic polyurethane in an oven at 100°C for 12 hours, dry the above-mentioned modified polyimide fiber in a vacuum oven at 120°C for 12 hours, and add 100 parts by weight of the vacuum-dried polyurethane to the internal kneading oven at 190°C. In the machine, set the rotation speed to 60 rpm. After melting for 3 minutes, add 1 part by weight of modified polyimide fiber and 0.25 part by weight of antioxidant 1010. Then, after kneading for 4 minutes, take it out to obtain the modified polyimide short fiber/thermoplastic polyurethane composite material. Take 20g of the composite material prepared by melt blending, place it in a 1mm mold, and then place it in a vacuum flat vulcanizer. The temperature is set to 200°C. It is preheated for 5 minutes, then hot pressed for 8 minutes, and cold pressed for 5 minutes. Take out the sample and leave it for 3-5 days for subsequent testing.

Example 6

Prepare a KOH solution with a concentration of 2 mol·L ^-1 , add the polyimide fiber that has been cleaned and dried at room temperature, and react with ultrasonic treatment and machine head stirring for 45 minutes respectively. After the treatment is completed, take out the fiber and use deionization Rinse with water 4-5 times. Prepare an acetic acid solution of 0.1 mol·L ^-1 . Protonate the fiber at room temperature for 10 minutes. After the reaction, wash it with deionized water 4-5 times. Dry the fiber in a vacuum oven at 100°C for 10 hours. , the modified polyimide fiber is obtained for use, and the length of the modified polyimide fiber is 3-5mm.

Dry the thermoplastic polyurethane in an oven at 100°C for 12 hours, dry the above-mentioned modified polyimide fiber in a vacuum oven at 120°C for 12 hours, and add 100 parts by weight of the vacuum-dried polyurethane to the internal kneading oven at 190°C. In the machine, set the rotation speed to 60 rpm. After melting for 3 minutes, add the calculated mass fraction of 1 part by weight of modified polyimide fiber and 0.25 part by weight of antioxidant 1010. Then, after mixing for 4 minutes, take out the composite materials with different polyimide fiber mass fractions. Take 20g of the composite material prepared by melt blending, place it in a 1mm mold, and then place it in a vacuum flat vulcanizer. The temperature is set to 200°C. It is preheated for 5 minutes, then hot pressed for 8 minutes, and cold pressed for 5 minutes. Take out the sample and leave it for 3-5 days for subsequent testing.

Example 7

Prepare a KOH solution with a concentration of 1 mol·L ^-1 , add the polyimide fiber that has been cleaned and dried at room temperature, and react with ultrasonic treatment and machine head stirring for 45 minutes respectively. After the treatment is completed, take out the fiber and use deionization Rinse with water 4-5 times. Prepare an acetic acid solution of 0.05 mol·L ^-1 . Protonate the fiber at room temperature for 10 minutes. After the reaction, wash it with deionized water 4-5 times. Dry the fiber in a vacuum oven at 100°C for 10 hours. , the modified polyimide fiber is obtained for use, and the length of the modified polyimide fiber is 3-5mm.

Dry the thermoplastic polyurethane in an oven at 100°C for 12 hours, dry the above-mentioned modified polyimide fiber in a vacuum oven at 120°C for 12 hours, and add 100 parts by weight of the vacuum-dried polyurethane to the internal kneading oven at 190°C. In the machine, set the rotation speed to 60 rpm. After melting for 3 minutes, add the calculated mass fraction of 1 part by weight of modified polyimide fiber and 0.25 part by weight of antioxidant 1010. Then, after mixing for 4 minutes, take out the composite materials with different polyimide fiber mass fractions. Take 20g of the composite material prepared by melt blending, place it in a 1mm mold, and then place it in a vacuum flat vulcanizer. The temperature is set to 200°C. It is preheated for 5 minutes, then hot pressed for 8 minutes, and cold pressed for 5 minutes. Take out the sample and leave it for 3-5 days for subsequent testing.

Example 8

Prepare a KOH solution with a concentration of 1 mol·L ^-1 , add the polyimide fiber that has been cleaned and dried at room temperature, and react with ultrasonic treatment and machine head stirring for 45 minutes respectively. After the treatment is completed, take out the fiber and use deionization Rinse with water 4-5 times. Prepare an acetic acid solution of 0.2 mol·L ^-1 . Protonate the fiber at room temperature for 10 minutes. After the reaction, wash it with deionized water 4-5 times. Dry the fiber in a vacuum oven at 100°C for 10 hours. , the modified polyimide fiber is obtained for use, and the length of the modified polyimide fiber is 3-5mm.

Dry the thermoplastic polyurethane in an oven at 100°C for 12 hours, dry the above-mentioned modified polyimide fiber in a vacuum oven at 120°C for 12 hours, and add 100 parts by weight of the vacuum-dried polyurethane to the internal kneading oven at 190°C. In the machine, set the rotation speed to 60 rpm. After melting for 3 minutes, add the calculated mass fraction of 1 part by weight of modified polyimide fiber and 0.25 part by weight of antioxidant 1010. Then, after mixing for 4 minutes, take out the composite materials with different polyimide fiber mass fractions. Take 20g of the composite material prepared by melt blending, place it in a 1mm mold, and then place it in a vacuum flat vulcanizer. The temperature is set to 200°C. It is preheated for 5 minutes, then hot pressed for 8 minutes, and cold pressed for 5 minutes. Take out the sample and leave it for 3-5 days for subsequent testing.

Example 9

Prepare a sodium hydroxide solution with a concentration of 1 mol·L ^-1 , add the polyimide fiber that has been cleaned and dried at room temperature, and react with ultrasonic treatment and machine head stirring for 45 minutes respectively. After the treatment is completed, take out the fiber and use it. Rinse 4-5 times with deionized water. Prepare an acetic acid solution of 0.1 mol·L ^-1 . Protonate the fiber at room temperature for 10 minutes. After the reaction, wash it with deionized water 4-5 times. Dry the fiber in a vacuum oven at 100°C for 10 hours. , the modified polyimide fiber is obtained for use, and the length of the modified polyimide fiber is 3-5mm.

Dry the thermoplastic polyurethane in an oven at 100°C for 12 hours, dry the above-mentioned modified polyimide fiber in a vacuum oven at 120°C for 12 hours, and add 100 parts by weight of the vacuum-dried polyurethane to the internal kneading oven at 190°C. In the machine, set the rotation speed to 60 rpm. After melting for 3 minutes, add 1 part by weight of modified polyimide fiber and 0.5 part by weight of antioxidant 1010. Then, after mixing for 4 minutes, take out the composite materials with different polyimide fiber mass fractions. Take 20g of the composite material prepared by melt blending, place it in a 1mm mold, and then place it in a vacuum flat vulcanizer. The temperature is set to 200°C. It is preheated for 5 minutes, then hot pressed for 8 minutes, and cold pressed for 5 minutes. Take out the sample and leave it for 3-5 days for subsequent testing.

Comparative example 1

Polyurethane TPUE95 from Yantai Meirui New Materials Co., Ltd.

Comparative example 2

Dry the thermoplastic polyurethane in an oven at 100°C for 12 hours, dry the unmodified polyimide fiber in a vacuum oven at 120°C for 12 hours, and add 100 parts by weight of the vacuum-dried polyurethane to a dense oven at 190°C. In the mixing machine, set the rotation speed to 60 rpm. After melting for 3 minutes, add 1 part by weight of unmodified polyimide fiber and 0.25 part by weight of antioxidant 1010. Then, after mixing for 4 minutes, take out the composite materials with different polyimide fiber mass fractions. Take 20g of the composite material prepared by melt blending, place it in a 1mm mold, and then place it in a vacuum flat vulcanizer. The temperature is set to 200°C. It is preheated for 5 minutes, then hot pressed for 8 minutes, and cold pressed for 5 minutes. Take out the sample and leave it for 3-5 days for subsequent testing.

Perform performance tests on the examples and comparative examples, and the test methods are as follows:

Tensile test method: National standard GB/T 531.1-2008. Stretching speed: 500mm/min, sample size: 25mm*4mm*1mm.

DMA test method: dynamic tensile mode, temperature range: -100-125°C, strain: 0.1%, frequency: 10Hz, heating rate: 3°C/min.

The test results are shown in Table 2:

Table 2

Combining the test results in Table 2 and Figure 1, it can be seen that as the content of the modified polyimide fiber added increases in Examples 1-4, the tensile strength first increases and then decreases. In Example 2, The tensile strength of the modified polyimide fiber/polyurethane composite obtained by adding 1wt% modified polyimide fiber to polyurethane is the highest. Compared to Comparative Example 1, which does not add any filler to TPUE95 and Comparative Example 2, which adds modified polyimide fiber, Example 2 is a modified polyimide obtained by adding 1wt% modified polyimide fiber to polyurethane. The tensile strength of the fiber/polyurethane composite material has been significantly improved, indicating that the surface roughness of the polyimide fiber has been changed through modification of polyimide fiber, polar groups have been added, and the relationship between polyimide fiber and polyurethane has been changed. However, when 2wt% and 3wt% modified polyimide fibers are added in Examples 3 and 4, the tensile strength of the composite material has an obvious performance decrease, which is mainly due to the physical entanglement of the fibers. knots, causing defects and leading to a decrease in the mechanical properties of polyimide fiber/polyurethane composites. Among them, it can be seen from Examples 6 and 8 that excessive concentration of KOH or excessive acid concentration will cause damage to the polyimide fiber and cause a decrease in fiber strength. As a result, the tensile strength of the composite material is not as good as before. When adding fiber. The serious performance degradation in Example 9 is also due to the fact that NaOH may cause serious damage to the structure of the polyimide fiber. In Examples 5 and 7, the concentration of KOH used in Examples 5 and 7 is lower, the modification of the polyimide fiber is incomplete, and there are fewer polar groups formed on the surface. Therefore, although the tensile strength is higher than that of the Comparative Example, it is not as good as the Comparative Example. 2 Tensile strength is small.

Combining the test results in Table 2 and the dynamic mechanical performance storage modulus diagram in Figure 2, it can be seen that the addition of modified polyimide fiber will increase the storage modulus of the composite material, and as the content increases, 120 The storage modulus also increases at 120°C; and compared to the addition of unmodified polyimide fiber in Comparative Example 2, the storage modulus of the modified polyimide fiber at 120°C is compared to the comparative example. 1The increase of TPUE95 without any filler is more obvious.

The present invention greatly improves the modulus and thermal coupling performance of polyurethane by adding a small amount of polyimide fiber modified with an alkali solution. Through modification, the interface between fiber and polyurethane is greatly improved, achieving excellent mechanical properties and thermal coupling properties, and improving the problems of severe endogenous heat generation and poor stability of polyurethane. The prepared polyimide fiber/polyurethane Composite materials can be used in tires, shock absorbers, etc. When a small amount of modified polyimide fiber is added to thermoplastic polyurethane, its performance can be greatly improved, which also saves production costs and expands the application scope of polyurethane composite materials.

Claims (10)

1. The modified polyimide short fiber/thermoplastic polyurethane composite material is characterized by being prepared from the following raw materials in parts by weight:

100 parts by weight of thermoplastic polyurethane;

0.5-5 parts by weight of modified polyimide fiber;

0.1-0.5 part of antioxidant.

2. The modified polyimide staple fiber/thermoplastic polyurethane composite of claim 1, wherein: the raw materials are as follows in parts by weight:

100 parts by weight of thermoplastic polyurethane;

0.5-3 parts by weight of modified polyimide fiber;

0.1-0.3 part of antioxidant.

3. The modified polyimide staple fiber/thermoplastic polyurethane composite of claim 1, wherein:

the modified polyimide fiber is obtained by carrying out ultrasonic treatment on the polyimide fiber in an alkali solution and protonation treatment in an acid solution.

4. The modified polyimide staple fiber/thermoplastic polyurethane composite of claim 3, wherein: the modified polyimide fiber is prepared by a method comprising the following steps:

(1) Carrying out ultrasonic treatment on polyimide fibers in an alkali solution;

the alkali solution is potassium hydroxide solution or sodium hydroxide solution, and the ultrasonic treatment time is 10-60min;

(2) Placing the polyimide fiber subjected to ultrasonic treatment in an acid solution for protonation treatment;

the acid solution is acetic acid solution, and the treatment time is 10-20min.

5. The modified polyimide staple fiber/thermoplastic polyurethane composite of claim 4, wherein:

the concentration of the alkali solution in the step (1) is 0.5-2mol/L; the concentration of the acid solution in the step (2) is 0.05-0.3mol/L.

6. The modified polyimide staple fiber/thermoplastic polyurethane composite of claim 4, wherein:

and (3) carrying out ultrasonic treatment on the polyimide fiber in the alkaline solution in the step (1) and carrying out protonation treatment in the acid solution in the step (2), and drying at the temperature of 90-110 ℃ for 8-12h to obtain the modified polyimide fiber.

7. The modified polyimide staple fiber/thermoplastic polyurethane composite of claim 1, wherein: the length of the modified polyimide fiber is 1-15mm.

8. A process for preparing a modified polyimide staple fiber/thermoplastic polyurethane composite according to any one of claims 1 to 7, comprising:

the components are melt blended according to the amount to prepare the modified polyimide short fiber/thermoplastic polyurethane composite material.

9. The method for preparing the modified polyimide short fiber/thermoplastic polyurethane composite material according to claim 8, which is characterized in that: the melting temperature is 190-210 ℃ and the time is 3-5min.

10. The method for preparing the modified polyimide short fiber/thermoplastic polyurethane composite material according to claim 8, which is characterized in that: the blending temperature is 190-210 ℃, the rotating speed is 50-80rpm, and the time is 4-8min.