High-shear-resistance carbon fiber reinforced polyimide composite material and preparation method thereof

Abstract

The invention discloses a high-shear-resistance carbon fiber reinforced polyimide composite material and a preparation method thereof, and belongs to the technical field of carbon fiber composites.The preparation method comprises the following steps that S1, magnetic carbon nanotube dispersion liquid is slowly dropwise added into a polyimide solution to be stirred and mixed, and a modified polyimide glue solution is obtained; s2, sequentially drawing a carbon fiber tow to a vibrator, an infiltration tank filled with a modified polyimide glue solution and external magnetic field equipment, finally fixing the carbon fiber tow on a roller arrangement machine, taking down the carbon fiber tow after infiltration, magnetization, arrangement and curing, and removing redundant organic solvent at high temperature to obtain a carbon fiber unidirectional prepreg tape; s3, the carbon fiber unidirectional prepreg tape is subjected to overlapping and hot press molding, and the carbon fiber reinforced polyimide composite material is obtained; the preparation method disclosed by the invention is simple, low in production cost and easy for industrial batch production, and the prepared carbon fiber reinforced polyimide composite material has the advantages of high strength, high shear strength, good thermal stability and excellent processability.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon fiber composite materials, and particularly relates to a high shear resistance carbon fiber reinforced polyimide composite material and a preparation method thereof. Background Art

[0002] Carbon fiber has the advantages of high temperature resistance, high strength, large modulus, and light weight. It is widely used in aerospace, wind power, marine ships, automobiles, rail transportation and other fields. However, the preparation, modification and material processing technologies of carbon fiber composites are the main bottlenecks for the development of carbon fiber composites for high-end applications. As the "bond" between carbon fiber and resin matrix, the microstructure and bonding of the interface directly determine the ultimate performance and usability of carbon fiber composites, and it is also the weakest link in the overall performance of carbon fiber composites. Effective modification of the carbon fiber / matrix interface is an important way to improve the interface performance of fiber composites. At present, there are two main aspects of interface modification of carbon fiber composites: one is the surface modification of carbon fiber; the other is the modification of resin matrix.

[0003] A Chinese patent application with publication number CN117360009A discloses a polyimide composite material and a preparation method thereof, wherein a carbon nanotube fiber cloth / polyimide prepreg is designed and laid as a skin layer, and a carbon fiber reinforced polyimide prepreg is designed and laid as a core layer to prepare a polyimide composite material; although the conductivity of the material is greatly improved, the interlaminar shear strength of the carbon fiber reinforced polyimide composite material is only slightly improved.

[0004] The Chinese patent application with publication number CN117802777A discloses a vertical carbon nanotube grafted carbon fiber, a carbon fiber composite material and a preparation method. By introducing a bioactive glass coating on the surface of the carbon fiber, a vertical carbon nanotube is quickly grown on the surface of the carbon fiber by using a catalytic chemical deposition method, and a vertical carbon nanotube grafted carbon fiber and a carbon fiber composite material are prepared. Although the mechanical properties of the material are significantly improved, this method is not suitable for mass production because it modifies the carbon fiber.

[0005] A Chinese patent application with publication number CN102181152A discloses a method for preparing a carbon nanotube-modified carbon fiber / polyimide resin multidimensional hybrid composite material, comprising: subjecting carbon nanotubes and carbon fibers to surface carboxylation and acylation, introducing diamine or polyamine thereon, uniformly mixing the amino carbon nanotubes with the polyimide resin, and then compounding with a functionalized carbon fiber reinforcement after vacuum debubbling and curing reaction to obtain a carbon nanotube-modified carbon fiber / polyimide resin multidimensional hybrid composite material; although this method can improve the interlaminar shear strength by mixing carbon nanotubes, the disordered mixing state of carbon fibers and carbon nanotubes and the state in which most of the carbon nanotubes are grafted on the surface of carbon fibers do not significantly improve the overall performance, and the complicated preparation process increases the cost.

[0006] Therefore, how to prepare carbon fiber reinforced polyimide composite materials with high shear strength in large quantities is a technical problem that needs to be solved urgently. Summary of the invention

[0007] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a high shear resistance carbon fiber reinforced polyimide composite material and a preparation method thereof, so that the prepared composite material has the advantages of high strength, high shear resistance, good thermal stability and excellent processing performance, and the preparation process is simple and easy to industrialize and mass produce.

[0008] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing a high shear resistance carbon fiber reinforced polyimide composite material comprises the following steps: S1. Preparation of modified polyimide glue The polyimide powder is added to an organic solvent and stirred to dissolve to obtain a polyimide solution; the magnetic carbon nanotubes are added to the organic solvent in multiple times, and after alternating high and low speed stirring and ultrasonic dispersion, a magnetic carbon nanotube dispersion is obtained; the magnetic carbon nanotube dispersion is slowly added dropwise to the polyimide solution, and stirring is continued for 30-60 minutes to uniformly disperse the magnetic carbon nanotubes in the polyimide solution to obtain a modified polyimide glue solution; S2. Preparation of carbon fiber unidirectional prepreg tape The modified polyimide glue is poured into the impregnation tank, and the carbon fiber tow is sequentially pulled to the vibrator, the impregnation tank and the external magnetic field device, and finally fixed on the roller arrangement machine. The two poles of the external magnetic field device are located on the left and right sides of the carbon fiber tow, and the magnetic field direction is perpendicular to the pulling direction of the carbon fiber tow. The magnetic field strength is 0.5-25T. The carbon fiber tow is taken out from the roller arrangement machine after impregnation, magnetization, arrangement and curing, and is further removed by high-temperature drying to obtain a carbon fiber unidirectional prepreg tape after the excess organic solvent is removed. If the magnetic field strength is too small, it is not conducive to the orientation of magnetic carbon nanotubes, and if the magnetic field strength is too large, it will consume too much electricity and increase production costs. S3. Preparation of high shear resistance carbon fiber composite materials The carbon fiber unidirectional prepreg tapes are stacked and hot-pressed at a temperature of 320-460°C and a pressure of 1-3MPa to obtain a high shear resistance carbon fiber reinforced polyimide composite material; the number of stacked layers is 10-50 layers, and the specific number of stacked layers is set according to the actual needs of the product to be molded.

[0009] The inventors found that the polyimide glue dissolved in an organic solvent can well infiltrate the carbon fiber tow after yarn unwinding, but when solidified on the subsequent roller arrangement machine, the polyimide resin will precipitate from between the carbon fiber filaments to the surface of the carbon fiber tow as the solvent evaporates. If the polyimide glue is not modified by adding magnetic carbon nanotubes, only a very small amount of polyimide resin will remain between the carbon fiber filaments, thereby affecting the mechanical properties of the carbon fiber reinforced polyimide composite material, especially the interlaminar shear strength.

[0010] Furthermore, the mass ratio of the polyimide powder to the organic solvent is 1:5; the polyimide powder is a soluble polyimide, and the molecular weight of the polyimide is 50,000-140,000. If the molecular weight of the polyimide is too low, the mechanical properties of the composite material will be insufficient, and if the molecular weight of the polyimide is too high, the polyimide powder will not be completely dissolved in the organic solvent. The mass ratio of the magnetic carbon nanotubes to the organic solvent is 0.005-0.015:1; the organic solvent is any one of N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone. The amount of magnetic carbon nanotubes should not be too much, otherwise it will cause the magnetic carbon nanotubes to entangle and agglomerate with each other.

[0011] Furthermore, the magnetic carbon nanotubes are prepared by the following steps: Step A1, calcining and reducing a metal nitrate and a montmorillonite under the protection of an inert gas after a cation exchange treatment to obtain a metal / montmorillonite catalyst, then mixing the metal / montmorillonite catalyst with waste polyolefins, cooling and crushing the discharged material to obtain a waste polyolefin composite, placing the waste polyolefin composite in a tubular furnace, heat-treating it at 700-900° C. for 2-6 hours under the protection of an inert gas to obtain a carbon nanotube / montmorillonite hybrid material, ultrasonically separating it, and then acidifying it to obtain a modified carbon nanotube; Step A2, ultrasonically dissolve the iron salt in deionized water, then add the modified carbon nanotubes and stir to disperse, heat to 70-90°C under nitrogen protection, slowly add 5wt% ammonia water until the pH value is 8-10, stir to react for 0.5-2h, filter and wash the filter residue with deionized water until it is neutral, and obtain magnetic carbon nanotubes.

[0012] Furthermore, the mass ratio of the montmorillonite to the metal nitrate is 1:0.1-0.3; the metal nitrate includes but is not limited to any one or more combinations of iron nitrate, nickel nitrate, cobalt nitrate, magnesium nitrate, aluminum nitrate, and manganese nitrate.

[0013] Furthermore, the mass ratio of the metal / montmorillonite catalyst to the waste polyolefin is 1:80-100.

[0014] Furthermore, the usage ratio of the iron salt, deionized water and modified carbon nanotubes is 0.6-0.7 g:160-180 mL:0.4-0.45 g; the iron salt includes but is not limited to ferric chloride and ferrous chloride.

[0015] Furthermore, the alternating high and low speed stirring refers to stirring alternately between a low speed of 100-400 r / min and a high speed of 600-1000 r / min every 1 minute.

[0016] Furthermore, the up and down vibration frequency of the vibrator is 20-100 Hz, and the amplitude is 1-5 mm; the roller temperature in the roller arrangement machine is 50-120° C., the arrangement tension is 4-15 N, and the arrangement speed is 10-25 m / min.

[0017] Furthermore, the thickness of the carbon fiber unidirectional prepreg tape is 0.01-0.5 mm; the ultra-thin carbon fiber unidirectional prepreg tape has good bendability and can be bent 0-180°, has simplified operation and excellent plasticity, and can be used to prepare carbon fiber composite materials products with various special-shaped structures.

[0018] A high shear resistance carbon fiber reinforced polyimide composite material is prepared by the above preparation method.

[0019] Beneficial effects: 1. The present invention uses cheap waste polyolefin plastics as a carbon source, prepares high value-added carbon nanotubes by catalytic cracking, and then acidifies the carbon nanotubes separated from montmorillonite to obtain modified carbon nanotubes; then, Fe is heated under alkaline conditions. 2+ and Fe 3+ The carbon nanotubes are co-precipitated and converted into magnetic nanoparticles, which are attached to the surface of the modified carbon nanotubes or embedded in their structure to obtain high-value magnetic carbon nanotubes. The carbon nanotubes of the present invention are derived from waste polyolefins, which helps to reduce white pollution, realize the concept of green environmental protection, and greatly reduce production costs. 2. The present invention uses a vibrator to spread the carbon fiber tow, so that the carbon fiber tow is widened and thinned, thereby ensuring that the carbon fiber tow is fully infiltrated with the modified polyimide glue; due to the nanometer size effect of the magnetic carbon nanotubes in the modified polyimide glue, the magnetic carbon nanotubes loaded on the carbon fiber monofilaments by electrostatic action bind the polyimide resin inside the carbon fiber tow through capillary action, thereby making the polyimide resin evenly distributed in the carbon fiber tow, which is beneficial to improving the uniform stability of the carbon fiber reinforced polyimide composite material; 3. The present invention applies an external magnetic field to orient the magnetic carbon nanotubes between the carbon fiber filaments. On the one hand, the dispersion of the magnetic carbon nanotubes is improved due to the repulsion of the magnetic carbon nanotubes in the magnetic field. On the other hand, under the action of the external magnetic field, the magnetic carbon nanotubes are oriented perpendicular to the carbon fiber bundles, so that the magnetic carbon nanotubes are overlapped between multiple carbon fiber filaments, forming a "net structure" with carbon fibers as warps and magnetic carbon nanotubes as wefts, so that the polyimide resin is better retained between the carbon fiber bundles, solving the problem of polyimide resin migrating to the surface of the carbon fiber bundle due to the volatilization of organic solvents in the composite material molding process, and providing a reliable solution for preparing high-performance carbon fiber reinforced composite materials. In addition, the mechanical bite effect at the interface between the magnetic carbon nanotubes and the carbon fiber bundles significantly improves the interface performance of the carbon fiber reinforced polyimide composite material, especially the shear resistance is greatly improved.

[0020] 4. The preparation method of the present invention is simple, has low production cost, and is easy to industrialize and mass produce. The obtained carbon fiber reinforced polyimide composite material has the advantages of high strength, high shear strength, good thermal stability and excellent processing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings.

[0022] Figure 1 is a cross-sectional scanning electron micrograph of the carbon fiber unidirectional prepreg tape prepared in Example 6 of the present invention; Figure 2 This is a cross-sectional scanning electron micrograph of the carbon fiber unidirectional prepreg tape prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1 This embodiment provides a magnetic carbon nanotube, which is prepared by the following steps: Step A1, 1g of montmorillonite (Zhejiang Fenghong New Materials Co., Ltd.) was added to 200mL of deionized water and magnetically stirred for 1h, and then ultrasonicated for 4h to obtain a montmorillonite suspension; 0.3g of ferric nitrate hexahydrate was added to 10mL of deionized water and stirred to dissolve, and then poured into the montmorillonite suspension and stirred and immersed for 24h, after cation exchange treatment, the filter residue was filtered and dried at 100°C, ground and sieved through a 200-mesh sieve, and then transferred to a quartz boat in a tubular furnace, the tubular furnace was first passed with argon for 30min, and then heated to 500°C at a heating rate of 5°C / min, calcined for 3h under argon protection, and cooled to room temperature to obtain an iron / montmorillonite catalyst; 0 .1g of iron / montmorillonite catalyst was mixed evenly with 10g of waste polyethylene, and then added into an internal mixer, and internally mixed at a speed of 40r / min and a temperature of 170°C. After the internal mixing torque curve was flat, the internal mixing was continued for 10min. After the discharged material was cooled, it was crushed into powder with a multifunctional pulverizer for later calcination to obtain a waste polyolefin composite; the waste polyolefin composite was placed in a tubular furnace, heat treated at 900°C for 2h under argon protection, and cooled to room temperature to obtain a carbon nanotube / montmorillonite hybrid material, and the carbon nanotubes were obtained by ultrasonic separation, and the carbon nanotubes were acidified with a mixed acid (volume ratio of concentrated sulfuric acid: concentrated nitric acid = 3:1) to obtain modified carbon nanotubes; Step A2, ultrasonically dissolve 0.45g FeCl3·6H2O and 0.15g FeCl2·4H2O iron salts in 160mL deionized water, then add 0.4g modified carbon nanotubes and stir to disperse, heat to 80°C under nitrogen protection, slowly add 5wt% ammonia water at a rate of 1mL / min to a pH value of 9, stir to react for 1h, filter and wash the residue with deionized water until it is neutral, and obtain magnetic carbon nanotubes.

[0025] Example 2 This embodiment provides a magnetic carbon nanotube, which is prepared by the following steps: Step A1, adding 1g of montmorillonite to 200mL of deionized water, stirring magnetically for 1h, and then ultrasonicating for 4h to obtain a montmorillonite suspension; adding 0.1g of nickel nitrate hexahydrate to 10mL of deionized water, stirring to dissolve, and then pouring into the montmorillonite suspension, stirring and impregnating for 24h, after cation exchange treatment, filtering and drying the filter residue at 100°C, grinding and passing through a 200-mesh sieve, and then transferring to a quartz boat in a tubular furnace, first passing argon gas through the tubular furnace for 30min, then heating to 500°C at a heating rate of 5°C / min, calcining for 3h under argon protection, and cooling to room temperature to obtain a nickel / montmorillonite catalyst; 0.1g of nickel / montmorillonite catalyst was uniformly mixed with 8g of waste polypropylene, and then added into an internal mixer, and internally kneaded at a speed of 40r / min and a temperature of 170°C. After the internal kneading torque curve was flat, the internal kneading was continued for 10min. After the discharged material was cooled, it was crushed into powder with a multifunctional pulverizer for later calcination to obtain a waste polyolefin composite; the waste polyolefin composite was placed in a tubular furnace, heat-treated at 850°C for 3h under argon protection, and cooled to room temperature to obtain a carbon nanotube / montmorillonite hybrid material, and carbon nanotubes were obtained by ultrasonic separation, and the carbon nanotubes were acidified with concentrated hydrochloric acid to obtain modified carbon nanotubes; Step A2, ultrasonically dissolve 0.48g FeCl3·6H2O and 0.18g FeCl2·4H2O iron salts in 170mL deionized water, then add 0.43g modified carbon nanotubes and stir to disperse, heat to 90°C under nitrogen protection, slowly add 5wt% ammonia water at a rate of 1mL / min to a pH value of 10, stir and react for 0.5h, filter and wash the residue with deionized water until it is neutral, and obtain magnetic carbon nanotubes.

[0026] Example 3 This embodiment provides a magnetic carbon nanotube, which is prepared by the following steps: Step A1, 1g of montmorillonite was added to 200mL of deionized water and magnetically stirred for 1h, and then ultrasonicated for 4h to obtain a montmorillonite suspension; 0.2g of cobalt nitrate hexahydrate was added to 10mL of deionized water and stirred to dissolve, and then poured into the montmorillonite suspension and stirred and immersed for 24h, after cation exchange treatment, the filter residue was filtered and dried at 100°C, ground and sieved through a 200-mesh sieve, and then transferred to a quartz boat in a tubular furnace, the tubular furnace was first passed with argon for 30min, and then heated to 500°C at a heating rate of 5°C / min, calcined for 3h under argon protection, and cooled to room temperature to obtain a cobalt / montmorillonite catalyst; 0 .1g of cobalt / montmorillonite catalyst was mixed evenly with 9g of waste polyethylene, and then added into an internal mixer, and internally kneaded at a speed of 40r / min and a temperature of 170°C. After the internal kneading torque curve was flat, the internal kneading was continued for 10min. After the discharged material was cooled, it was crushed into powder with a multifunctional pulverizer for later calcination to obtain a waste polyolefin composite; the waste polyolefin composite was placed in a tubular furnace, heat-treated at 700°C for 6h under inert gas protection, and cooled to room temperature to obtain a carbon nanotube / montmorillonite hybrid material, and carbon nanotubes were obtained by ultrasonic separation, and the carbon nanotubes were acidified with concentrated hydrochloric acid to obtain modified carbon nanotubes; Step A2, ultrasonically dissolve 0.5g FeCl3·6H2O and 0.2g FeCl2·4H2O iron salts in 180mL deionized water, then add 0.45g modified carbon nanotubes and stir to disperse, heat to 70°C under nitrogen protection, slowly add 5wt% ammonia water at a rate of 1mL / min to a pH value of 8, stir to react for 2h, filter and wash the residue with deionized water until neutral, to obtain magnetic carbon nanotubes.

[0027] Comparative Example 1 The difference between this comparative example and Example 3 is that the operation of step A2 is not performed, and the modified carbon nanotubes are directly used in the subsequent comparative examples.

[0028] Example 4 This embodiment provides a high shear resistance carbon fiber reinforced polyimide composite material, which is prepared by the following preparation method: S1, adding 10g of polyimide powder to 50g of N,N-dimethylacetamide and stirring at a speed of 300r / min to dissolve to obtain a polyimide solution; adding 0.05g of the magnetic carbon nanotubes obtained in Example 1 to 10g of N,N-dimethylacetamide in 4 times, stirring alternately at high and low speeds of 400r / min and 1000r / min every 1min for 2h, and then ultrasonicating for 30min to obtain a magnetic carbon nanotube dispersion; slowly dropping the above magnetic carbon nanotube dispersion into the polyimide solution and stirring and mixing for 30min to uniformly disperse the magnetic carbon nanotubes in the polyimide solution to obtain a modified polyimide glue; S2. Pour the modified polyimide glue into the impregnation tank, and then pull the carbon fiber tow to the vibrator, the impregnation tank and the external magnetic field device in turn, and finally fix it on the roller arrangement machine. The two poles of the external magnetic field device are located on the left and right sides of the carbon fiber tow, and the magnetic field direction is perpendicular to the pulling direction of the carbon fiber tow. The magnetic field strength is 0.5T. Turn on the vibrator and the roller arrangement machine, and keep the up and down vibration frequency of the vibrator at 100Hz and the amplitude at 1mm; the roller temperature in the roller arrangement machine is 500℃, the arrangement tension is 8N, and the arrangement speed is 25m / min. After the carbon fiber tow is impregnated, magnetized, arranged and cured, it is removed from the roller arrangement machine, and after high-temperature drying to further remove excess organic solvent, a carbon fiber unidirectional prepreg tape with a thickness of 0.05mm is obtained; S3. Stack 10 layers of carbon fiber unidirectional prepreg tapes, hot-press them at a temperature of 320° C. and a pressure of 1 MPa for 2 h, and release the pressure after cooling to 200° C. to obtain a high shear-resistant carbon fiber reinforced polyimide composite material.

[0029] Example 5 This embodiment provides a high shear resistance carbon fiber reinforced polyimide composite material, which is prepared by the following preparation method: S1, adding 10g of polyimide powder to 50g of N,N-dimethylformamide and stirring at a speed of 600r / min to dissolve to obtain a polyimide solution; adding 0.1g of the magnetic carbon nanotubes prepared in Example 2 to 10g of N,N-dimethylformamide in 5 times, stirring alternately at high and low speeds of 100r / min and 600r / min every 1min for 3h, and then ultrasonicating for 20min to obtain a magnetic carbon nanotube dispersion; slowly dropping the above magnetic carbon nanotube dispersion into the polyimide solution and stirring and mixing for 40min to uniformly disperse the magnetic carbon nanotubes in the polyimide solution to obtain a modified polyimide glue; S2. Pour the modified polyimide glue into the impregnation tank, and then pull the carbon fiber tow to the vibrator, the impregnation tank and the external magnetic field device in turn, and finally fix it on the roller arrangement machine. The two poles of the external magnetic field device are located on the left and right sides of the carbon fiber tow, and the magnetic field direction is perpendicular to the pulling direction of the carbon fiber tow. The magnetic field strength is 15T. Turn on the vibrator and the roller arrangement machine, and keep the vibrator up and down vibration frequency at 50Hz and the amplitude at 3mm; the roller temperature in the roller arrangement machine is 80°C, the arrangement tension is 4N, and the arrangement speed is 10m / min. After the carbon fiber tow is impregnated, magnetized, arranged and cured, it is removed from the roller arrangement machine, and after high-temperature drying to further remove excess organic solvent, a carbon fiber unidirectional prepreg tape with a thickness of 0.01mm is obtained; S3. Stack 10 layers of carbon fiber unidirectional prepreg tapes, hot-press them at a temperature of 400°C and a pressure of 2 MPa for 1.5 hours, and release the pressure after cooling to 200°C to obtain a high shear-resistant carbon fiber reinforced polyimide composite material.

[0030] Example 6 This embodiment provides a high shear resistance carbon fiber reinforced polyimide composite material, which is prepared by the following preparation method: S1, adding 10g of polyimide powder to 50g of N-methylpyrrolidone and stirring at a speed of 900r / min to dissolve to obtain a polyimide solution; adding 0.15g of the magnetic carbon nanotubes obtained in Example 3 to 10g of N-methylpyrrolidone in 5 times, stirring alternately at high and low speeds of 300r / min and 800r / min every 1min for 3h, and then ultrasonicating for 10min to obtain a magnetic carbon nanotube dispersion; slowly dropping the above magnetic carbon nanotube dispersion into the polyimide solution and stirring and mixing for 60min to uniformly disperse the magnetic carbon nanotubes in the polyimide solution to obtain a modified polyimide glue; S2. Pour the modified polyimide glue into the impregnation tank, and then pull the carbon fiber tow to the vibrator, the impregnation tank and the external magnetic field device in turn, and finally fix it on the roller arrangement machine. The two poles of the external magnetic field device are located on the left and right sides of the carbon fiber tow, and the magnetic field direction is perpendicular to the pulling direction of the carbon fiber tow. The magnetic field strength is 25T. Turn on the vibrator and the roller arrangement machine, and keep the up and down vibration frequency of the vibrator at 20Hz and the amplitude at 5mm; the roller temperature in the roller arrangement machine is 120℃, the arrangement tension is 15N, and the arrangement speed is 15m / min. After the carbon fiber tow is impregnated, magnetized, arranged and cured, it is removed from the roller arrangement machine, and after high-temperature drying to further remove excess organic solvent, a carbon fiber unidirectional prepreg tape with a thickness of 0.1mm is obtained; Figure 1 As shown, the polyimide resin is evenly distributed inside the carbon fiber unidirectional prepreg tape without obvious precipitation. S3. Stack 10 layers of carbon fiber unidirectional prepreg tapes, hot-press them at a temperature of 460° C. and a pressure of 3 MPa for 1 h, and then release the pressure after cooling to 200° C. to obtain a high shear-resistant carbon fiber reinforced polyimide composite material.

[0031] Comparative Example 2 The difference between this comparative example and Example 6 is that the magnetic carbon nanotubes prepared in Example 3 are not added in step S1, and the other raw materials and steps are the same. Figure 2 As shown, the polyimide resin is gathered on the surface of the carbon fiber unidirectional prepreg tape, and only a very small amount of polyimide resin remains between the carbon fiber filaments.

[0032] Comparative Example 3 The difference between this comparative example and Example 6 is that the modified carbon nanotubes prepared in Comparative Example 1 are used to replace the magnetic carbon nanotubes prepared in Example 3 in equal amounts, and the remaining steps and raw materials are the same.

[0033] Comparative Example 4 The difference between this comparative example and Example 6 is that the magnetic field intensity in step S2 is 0, that is, the carbon fiber tow is not magnetized, and the other steps are the same.

[0034] Performance tests were performed on Examples 4 to 6 and Comparative Examples 2 to 4. According to the GB / T 1449-2005 standard, the bending properties of the carbon fiber reinforced polyimide composite material were tested using the CMT 6104 electronic universal testing machine of Shenzhen Xinsansi Company; according to the GB / T 1450.1-2005 standard, the interlaminar shear properties of the carbon fiber reinforced polyimide composite material were tested using the CMT 6104 electronic universal testing machine of Shenzhen Xinsansi Company; a thermogravimetric analyzer (model TG2) of Mettler Toledo, Switzerland, was used to test the thermal stability of the carbon fiber reinforced polyimide composite material by thermogravimetric analysis by heating the temperature from room temperature to 800° C. in an air atmosphere, and the temperature T 200° C. at which the composite material lost 5% weight by thermal decomposition was recorded respectively. d5% , Temperature T when thermal decomposition weight loss is 10% d10% and the temperature T when the thermal decomposition weight loss is 30% d30% The results are shown in Table 1: Table 1 It can be seen from the data in Table 1 that the mechanical properties and thermal stability of the carbon fiber reinforced polyimide composite materials prepared in Examples 4 to 6 are significantly better than those of the carbon fiber reinforced polyimide composite materials prepared in Comparative Examples 2 to 4. This is because the directionally arranged magnetic carbon nanotubes and the carbon fiber bundles form a "network structure", which can better retain the polyimide resin between the carbon fiber bundles, and the magnetic carbon nanotubes can also act as a link between the carbon fiber bundles and the polyimide resin, so that a mechanical meshing effect is formed between the carbon fiber bundles and the polyimide resin, thereby improving the interface bonding strength and thus improving the mechanical properties and thermal stability of the composite material.

[0035] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0036] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high shear resistance carbon fiber reinforced polyimide composite material, It is characterized in that The steps include: S1, adding polyimide powder to an organic solvent and stirring to dissolve to obtain a polyimide solution; adding magnetic carbon nanotubes to the organic solvent in multiple times, stirring at alternating high and low speeds and ultrasonically dispersing to obtain a magnetic carbon nanotube dispersion; slowly dropping the magnetic carbon nanotube dispersion into the polyimide solution and continuing to stir to obtain a modified polyimide glue; S2, pulling the carbon fiber tow to a vibrator, an impregnation tank filled with modified polyimide glue, and an external magnetic field device in sequence, and finally fixing it on a roller arrangement machine, wherein the two poles of the external magnetic field device are located on the left and right sides of the carbon fiber tow, and the carbon fiber tow is removed from the roller arrangement machine after impregnation, magnetization, arrangement and curing, and dried to obtain a carbon fiber unidirectional prepreg tape; S3. The carbon fiber unidirectional prepreg tapes are stacked and hot-pressed at a temperature of 320-460° C. and a pressure of 1-3 MPa to obtain a high shear resistance carbon fiber reinforced polyimide composite material.

2. The method for preparing a high shear resistance carbon fiber reinforced polyimide composite material according to claim 1, It is characterized in that The mass ratio of the polyimide powder to the organic solvent is 1:5; the polyimide powder is a soluble polyimide, and the molecular weight of the polyimide is 50000-140000; the mass ratio of the magnetic carbon nanotubes to the organic solvent is 0.005-0.015:1; the organic solvent is any one of N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

3. The method for preparing a high shear resistance carbon fiber reinforced polyimide composite material according to claim 1, It is characterized in that The magnetic carbon nanotubes are prepared by the following steps: Step A1, calcining and reducing a metal nitrate and a montmorillonite under the protection of an inert gas after a cation exchange treatment to obtain a metal / montmorillonite catalyst, then mixing the metal / montmorillonite catalyst with waste polyolefins, cooling and crushing the discharged material to obtain a waste polyolefin composite, heat-treating the waste polyolefin composite under the protection of an inert gas at 700-900° C. for 2-6 hours to obtain a carbon nanotube / montmorillonite hybrid material, ultrasonically separating, and then acidifying to obtain a modified carbon nanotube; Step A2, ultrasonically dissolve the iron salt in deionized water, then add the modified carbon nanotubes and stir to disperse, heat to 70-90°C under nitrogen protection, slowly add 5wt% ammonia water until the pH value is 8-10, stir to react for 0.5-2h, filter and wash the filter residue with deionized water until it is neutral, and obtain magnetic carbon nanotubes.

4. The method for preparing a high shear resistance carbon fiber reinforced polyimide composite material according to claim 3, It is characterized in that The mass ratio of the montmorillonite to the metal nitrate is 1:0.1-0.3; the metal nitrate includes but is not limited to any one or more combinations of iron nitrate, nickel nitrate, cobalt nitrate, magnesium nitrate, aluminum nitrate, and manganese nitrate.

5. The method for preparing a high shear resistance carbon fiber reinforced polyimide composite material according to claim 3, It is characterized in that The mass ratio of the metal / montmorillonite catalyst to the waste polyolefin is 1:80-100.

6. The method for preparing a high shear resistance carbon fiber reinforced polyimide composite material according to claim 3, It is characterized in that The usage ratio of the iron salt, deionized water and modified carbon nanotubes is 0.6-0.7 g:160-180 mL:0.4-0.45 g; the iron salt is ferric chloride and ferrous chloride.

7. The method for preparing a high shear resistance carbon fiber reinforced polyimide composite material according to claim 1, It is characterized in that The alternating high and low speed stirring refers to stirring alternately between a low speed of 100-400 r / min and a high speed of 600-1000 r / min every 1 minute.

8. The method for preparing a high shear resistance carbon fiber reinforced polyimide composite material according to claim 1, It is characterized in that The up and down vibration frequency of the vibrator is 20-100 Hz, and the amplitude is 1-5 mm; the roller temperature in the roller arrangement machine is 50-120° C., the arrangement tension is 4-15 N, and the arrangement speed is 10-25 m / min.

9. The method for preparing a high shear resistance carbon fiber reinforced polyimide composite material according to claim 1, It is characterized in that The thickness of the carbon fiber unidirectional prepreg tape is 0.01-0.5 mm.

10. A high shear resistance carbon fiber reinforced polyimide composite material, It is characterized in that Prepared by the preparation method according to any one of claims 1 to 9.

Images