Modified carbon fiber reinforced polyaryletherketone composite material and preparation method thereof

Abstract

The invention relates to the technical field of polyaryletherketone composite materials, in particular to a modified carbon fiber reinforced polyaryletherketone composite material and a preparation method thereof.The preparation method comprises the following steps that S1, polybenzimidazole is attached to the surface of phosphorus-containing group functionalized carbon fiber; s2, in a protective atmosphere, preheating polyaryletherketone in a mold pressing mold, then uniformly laying the phosphorus-containing group functionalized carbon fibers treated in the step S1 on a preheated polyaryletherketone material, and carrying out stepped mold pressing forming, so as to obtain the modified carbon fiber reinforced polyaryletherketone composite material. The interface shear strength of the carbon fiber reinforced polyaryletherketone composite material is greatly improved through the action of surface modification of the phosphoric acid on the carbon fiber and interface transition of the polybenzimidazole.

Description

Technical Field

[0001] This invention relates to the field of polyaryletherketone composite materials, specifically to modified carbon fiber reinforced polyaryletherketone composite materials and their preparation methods. Background Technology

[0002] Currently, carbon fiber (CF) reinforced polyether ether ketone (PEEK) composites are widely used in the aerospace field, but insufficient interfacial bonding strength limits the improvement of their mechanical properties. Existing technologies mainly increase the concentration of PEEK free radicals by high-temperature melting (at least 390°C) or extending the melting time to improve interfacial shear strength. However, high temperatures lead to excessive free radical generation, inducing covalent bonding and inhibiting interfacial crystal formation, resulting in decreased crystallinity and sacrificing material toughness and strength. Surface modification of carbon fibers relies on complex desizing and inert atmosphere heat treatment (such as defunctionalization at 1000°C), which is inefficient and has poor controllability of functional groups (only -COOH / -OH). While non-covalent interactions (π-π interactions, hydrogen bonding) promote interfacial crystal growth and improve crystallinity, the interfacial strength reinforced solely by crystals is limited. Therefore, a technical solution that balances high interfacial strength, synergistic crystal reinforcement, and efficient surface modification is urgently needed to obtain carbon fiber reinforced polyaryl ether ketone composites. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a modified carbon fiber reinforced polyaryl ether ketone composite material and its preparation method. This invention employs phosphorus-functionalized carbon fibers first bonded to PBI, and then molded with PAEK, which allows the modified carbon fibers to be completely impregnated with polyaryl ether ketone, resulting in higher interfacial strength in the composite material.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0005] The preparation method of modified carbon fiber reinforced polyaryl ether ketone composite material includes the following steps:

[0006] S1. To attach polybenzimidazole to the surface of phosphorus-functionalized carbon fibers;

[0007] S2. Under a protective atmosphere, polyaryletherketone is preheated in a molding die. Then, phosphorus-functionalized carbon fibers treated with S1 are evenly laid on the preheated polyaryletherketone material and stepped molding is performed to obtain modified carbon fiber reinforced polyaryletherketone composite material.

[0008] The composite material contains, by weight (100 wt%), 0.5%-1.5% polybenzimidazole, 40%-65% phosphorus-functionalized carbon fiber, and the balance is the polyaryl ether ketone.

[0009] Furthermore, the preheating temperature of the polyaryletherketone (PAEK) in the molding die is 360-380°C, and the preheating time is 40-100 minutes. During the preheating process, PAEK generates phenoxy radicals, and excessive free radicalization at high temperature (390°C) is avoided.

[0010] Furthermore, the method for obtaining the phosphorus-functionalized carbon fiber is as follows: commercial carbon fiber is immersed in a phosphoric acid solution with a mass percentage of 10wt%-50wt% and then heated. After the treatment, the fiber is washed with water and dried, so that the fiber surface has phosphate ester (P–O) and phosphoryl group (P=O) functional groups. The phosphoric acid solution can partially dissolve or swell the original epoxy sizing agent on the carbon fiber surface, and penetrate into the carbon fiber body at a certain concentration and high temperature, reacting and bonding with the exposed carbon fiber surface.

[0011] Furthermore, the ratio of the commercial carbon fiber to the phosphoric acid solution is 1g:5-20mL; the commercial carbon fiber is chopped carbon fiber and / or carbon fiber cloth.

[0012] Furthermore, the temperature of the heat treatment is in the range of 60-120°C, and the treatment time is in the range of 10-80 minutes.

[0013] Furthermore, the phosphorus-functionalized carbon fibers are sprayed with a polybenzimidazole dispersion, or the polybenzimidazole dispersion and the phosphorus-functionalized carbon fibers are mechanically stirred and mixed evenly, and then dried for later use.

[0014] The polybenzimidazole dispersion has a mass percentage of 5%-10%, and the solvent in the dispersion is water and / or an alcohol solvent. The polybenzimidazole in the dispersion is a fully aromatic PBI with a glass transition temperature of 418-427℃. Spraying the dispersion can form a uniform nanoscale PBI coating layer, which is superior to the uneven dispersion problem caused by melt blending carbon fibers and PBI.

[0015] Furthermore, the procedure for mechanically mixing the polybenzimidazole dispersion with phosphorus-functionalized carbon fibers is as follows: Under a protective atmosphere, place the phosphorus-functionalized carbon fibers in a high-speed mixer, add the polybenzimidazole dispersion in three to five batches at a speed of 500-1000 rpm, with a total mixing time of 20-80 minutes, and then dry them for later use.

[0016] Furthermore, the stepped molding process is a three-stage molding process, including a preheating stage, a molding stage, and an annealing stage;

[0017] The preheating section involves maintaining the temperature and pressure at 360-380℃ and 8-12MPa for 10-40 minutes to allow molten PAEK to fully penetrate the carbon fiber.

[0018] The molding section is heated to 380℃-385℃ and held at 12-20MPa for 5-15 minutes to promote the hydrogen bonding of PBI-PAEK phenoxy radicals and the bonding of phosphorus-containing groups.

[0019] The annealing section involves slowly cooling the temperature of the forming section to 180-220°C at a cooling rate of 1-3°C / min for annealing for 40-80 minutes. This slow cooling induces the growth of interfacial crystals along the fiber axis.

[0020] Furthermore, the polyaryl ether ketone is selected from one or more of polyether ether ketone (PEEK), polyether ketone (PEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), and polyether ketone ether ketone ketone (PEKEKK).

[0021] In another aspect, the present invention provides a modified carbon fiber reinforced polyaryletherketone composite material obtained by the above preparation method.

[0022] Beneficial technical effects: This invention uses a one-step phosphoric acid surface treatment of carbon fibers to avoid the adverse effects of high temperature on carbon fibers. The carbon fiber surface is modified by phosphoric acid to give it phosphorus-containing groups. Then, the phosphorus-containing functionalized carbon fibers are treated with polybenzazole dispersion. The phosphorus-containing groups on the carbon fiber surface and the polybenzazole interface have a transitional effect. At the same time, combined with a three-stage temperature-controlled molding process, the three can work together to greatly improve the interfacial shear strength of carbon fiber reinforced polyaryletherketone composite material, while retaining the toughness of the composite material to the greatest extent. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise specifically stated, the numerical values ​​set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that values ​​expressed, for example, as "within the range of ab" or "between the range of ab," do not include the endpoint values ​​a and b; values ​​expressed as "for ab," "is ab," or "ab" include the endpoint values ​​a and b.

[0025] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.

[0026] The polybenzimidazole used below is a fully aromatic PBI fine powder (Zhongyan JYPBI-100), with a glass transition temperature of 418-427℃, a tensile strength of 160MPa, and an elongation of 3%.

[0027] Example 1

[0028] This case study illustrates the preparation of phosphorus-functionalized carbon fibers:

[0029] Commercial carbon fiber T700 (chopped fiber, 7-10 micrometers in diameter and 6 millimeters in length) was immersed in a 20 wt% phosphoric acid solution (85 wt% concentrated phosphoric acid solution was diluted with anhydrous ethanol). The ratio of carbon fiber to phosphoric acid solution was 1 g: 10 mL. The solution was heated to 75°C for 40 minutes. Mechanical stirring was performed during the treatment to ensure uniformity. After the treatment, the solution was washed with water until neutral and dried to obtain phosphorus-functionalized carbon fiber, denoted as PCF-Ⅰ.

[0030] Example 2

[0031] This case study illustrates the preparation of phosphorus-functionalized carbon fibers:

[0032] Commercial carbon fiber T700 (short-cut fiber, 7-10 micrometers in diameter and 6 millimeters in length) was immersed in a 15 wt% phosphoric acid solution (85 wt% concentrated phosphoric acid solution was diluted with pure water). The ratio of carbon fiber to phosphoric acid solution was 1 g: 10 mL. The solution was heated to 80°C for 30 minutes. Mechanical stirring was performed during the treatment to ensure uniformity. After the treatment, the solution was washed with water until neutral and dried to obtain phosphorus-functionalized carbon fiber, denoted as PCF-II.

[0033] Example 3

[0034] This case study illustrates the preparation of phosphorus-functionalized carbon fibers:

[0035] Commercial carbon fiber T700 (short-cut fiber, 7-10 micrometers in diameter and 6 millimeters in length) was immersed in a 30 wt% phosphoric acid solution (85 wt% concentrated phosphoric acid solution was diluted with pure water). The ratio of carbon fiber to phosphoric acid solution was 1 g: 10 mL. The solution was heated to 90°C for 40 minutes. Mechanical stirring was performed during the treatment to ensure uniformity. After the treatment, the solution was washed with water until neutral and dried to obtain phosphorus-functionalized carbon fiber, denoted as PCF-Ⅲ.

[0036] Example 4

[0037] This case study describes a method for preparing modified carbon fiber reinforced polyaryl ether ketone composite materials, including the following steps:

[0038] S1. Under a protective atmosphere, take 65g of PCF-Ⅰ and place it in a high-speed mixer. Add 10g of polybenzimidazole dispersion in five batches at 800rpm. The total mixing time is 25min. After drying, set aside for use.

[0039] The polybenzimidazole dispersion used was a 10 wt% PBI fine powder-ethanol dispersion.

[0040] S2. Place 34.5g of PEEK fine powder (Junhua 5600P, 200 mesh) in a molding die. Under nitrogen protection, preheat the PEEK in the die to 375℃ for 80 minutes. Then, evenly lay PCF-I treated in S1 on the preheated PEEK material. Use a three-stage molding process, including a preheating stage, a molding stage, and an annealing stage. The preheating stage is to hold the temperature and pressure at 370℃ and 10MPa for 30 minutes to allow the molten PEEK to fully penetrate the carbon fiber. The molding stage is to hold the temperature and pressure at 380℃ and 15MPa for 10 minutes to promote the hydrogen bonding of PBI-PEEK phenoxy radicals and the bonding of phosphorus-containing groups. The annealing stage is to slowly cool from the temperature of the molding stage to 200℃ at a cooling rate of 2℃ / min for 60 minutes. Slow cooling induces the growth of interfacial crystals along the fiber axis, thus obtaining the modified carbon fiber reinforced polyaryl ether ketone composite material.

[0041] Example 5

[0042] This case study describes a method for preparing modified carbon fiber reinforced polyaryl ether ketone composite materials, including the following steps:

[0043] S1. Under a protective atmosphere, take 50g of PCF-II and place it in a high-speed mixer. Add 7g of polybenzimidazole dispersion in five batches at 1000rpm. The total mixing time is 20min. After drying, set aside for use.

[0044] The polybenzimidazole dispersion used was a 7.5 wt% PBI fine powder-ethanol dispersion.

[0045] S2. Place 49g of PEEK fine powder (Junhua 5600P, 200 mesh) in a molding die. Under nitrogen protection, preheat the PEEK in the die to 370℃ for 90 minutes. Then, evenly lay PCF-II treated in S1 on the preheated PEEK material. Use a three-stage molding process, including a preheating stage, a molding stage, and an annealing stage. The preheating stage involves holding the temperature and pressure at 370℃ and 10MPa for 30 minutes to allow the molten PEEK to fully penetrate the carbon fiber. The molding stage involves heating to 380℃ and holding the temperature and pressure at 15MPa for 10 minutes to promote the hydrogen bonding of PBI-PEEK phenoxy radicals and the bonding of phosphorus-containing groups. The annealing stage involves slowly cooling from the temperature of the molding stage to 180℃ at a cooling rate of 1℃ / min for 60 minutes. Slow cooling induces the growth of interfacial crystals along the fiber axis, thus obtaining the modified carbon fiber reinforced polyaryl ether ketone composite material.

[0046] Example 6

[0047] This case study describes a method for preparing modified carbon fiber reinforced polyaryl ether ketone composite materials, including the following steps:

[0048] S1. Under a protective atmosphere, take 58.5g of PCF-Ⅲ and place it in a high-speed mixer. Add 30g of polybenzimidazole dispersion in five batches at 900rpm. The total mixing time is 60min. After drying, set aside for use.

[0049] The polybenzimidazole dispersion used was a 5 wt% PBI fine powder-ethanol dispersion.

[0050] S2. Place 40g of PEEK fine powder (Junhua 5600P, 200 mesh) in a molding die. Under nitrogen protection, preheat the PEEK in the die to 365℃ for 100 minutes. Then, evenly lay PCF-Ⅲ treated in S1 on the preheated PEEK material. Use a three-stage molding process, including a preheating stage, a molding stage, and an annealing stage. The preheating stage is to hold the temperature and pressure at 370℃ and 10MPa for 30 minutes to allow the molten PEEK to fully penetrate the carbon fiber. The molding stage is to hold the temperature and pressure at 380℃ and 15MPa for 10 minutes to promote the hydrogen bonding of PBI-PEEK phenoxy radicals and the bonding of phosphorus-containing groups. The annealing stage is to slowly cool from the temperature of the molding stage to 190℃ at a cooling rate of 3℃ / min for 60 minutes. Slow cooling induces the growth of interfacial crystals along the fiber axis, thus obtaining the modified carbon fiber reinforced polyaryl ether ketone composite material.

[0051] Comparative Example 1

[0052] The preparation method of the composite material in this case is the same as that in Example 4, except that the carbon fiber was not treated with phosphoric acid solution, and only the original T700 short-cut fiber was used to replace PCF-I.

[0053] Comparative Example 2

[0054] The preparation method of the composite material in this case is the same as that in Example 4, except that the original T700 short-cut fibers are desized at 500°C for 20 minutes, and the CF after high-temperature desizing is used to replace PCF-Ⅰ.

[0055] Comparative Example 3

[0056] The preparation method of the composite material in this case is the same as that in Example 4, except that: after the original T700 short-cut fibers are desized at 500°C for 20 minutes, the carbon fibers after high-temperature desizing are oxidized with 30wt% H2O2 at room temperature for 10 hours. After washing with water and vacuum drying, OCF is obtained, and OCF is used to replace PCF-Ⅰ.

[0057] Comparative Example 4

[0058] The preparation method of the composite material in this case is the same as that in Example 4, except that PBI was not used to attach phosphorus-functionalized carbon fibers.

[0059] Performance tests were conducted on the above cases, and the results are shown in Table 1.

[0060] Table 1 Case Performance

[0061]

[0062] As shown in Table 1, the composite material prepared by the method of this invention has an interfacial shear strength of at least 48 MPa, while retaining its toughness to the maximum extent. Based on the toughness data of PEEK, the impact toughness retention rate of the composite material reaches over 80%. Comparative Example 1 uses raw chopped fibers, while Comparative Example 2 involves high-temperature desizing of the raw chopped fibers. However, because the surface of the raw chopped fibers in Comparative Example 1 has an epoxy sizing agent, and epoxy sizing agents have a poor effect on the interfacial strength of PEEK, the interfacial shear strength and mechanical strength of Comparative Example 1 are lower than those of Comparative Example 2. In Comparative Example 3, the raw chopped fibers are desizing at high temperature followed by hydrogen peroxide oxidation to form oxidized carbon fibers. After oxidation, the mechanical strength decreases significantly, the interfacial strength is poor, and the toughness is severely degraded compared to PEEK. Comparative Example 4 uses phosphorus-functionalized carbon fibers combined with PEEK, and the interfacial strength effect is also poor.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing modified carbon fiber reinforced polyaryl ether ketone composite materials, characterized in that, Includes the following steps: S1. To attach polybenzimidazole to the surface of phosphorus-functionalized carbon fibers; S2. Under a protective atmosphere, polyaryletherketone is preheated in a molding die. Then, phosphorus-functionalized carbon fibers treated with S1 are evenly laid on the preheated polyaryletherketone material and stepped molding is performed to obtain modified carbon fiber reinforced polyaryletherketone composite material. In the composite material, based on 100wt%, polybenzimidazole accounts for 0.5%-1.5%, phosphorus-functionalized carbon fiber accounts for 40%-65%, and the balance is polyaryl ether ketone.

2. The method for preparing the modified carbon fiber reinforced polyaryl ether ketone composite material according to claim 1, characterized in that, The method for obtaining the phosphorus-functionalized carbon fiber is as follows: commercial carbon fiber is immersed in a phosphoric acid solution with a mass percentage of 10wt%-50wt% and heated, and then washed and dried after the treatment.

3. The method for preparing the modified carbon fiber reinforced polyaryl ether ketone composite material according to claim 2, characterized in that, The ratio of the commercial carbon fiber to the phosphoric acid solution is 1g:5-20mL; the commercial carbon fiber is chopped carbon fiber and / or carbon fiber cloth.

4. The method for preparing the modified carbon fiber reinforced polyaryl ether ketone composite material according to claim 2, characterized in that, The heat treatment temperature is in the range of 60-120℃ and the treatment time is in the range of 10-80 minutes.

5. The method for preparing the modified carbon fiber reinforced polyaryl ether ketone composite material according to claim 2, characterized in that, The phosphorus-functionalized carbon fibers are sprayed with a polybenzimidazole dispersion, or the polybenzimidazole dispersion and the phosphorus-functionalized carbon fibers are mechanically stirred and mixed evenly, then dried for later use. The polybenzimidazole dispersion has a mass percentage of 5%-10%, and the solvent in the dispersion is water and / or an alcohol solvent, wherein the polybenzimidazole is a fully aromatic PBI with a glass transition temperature of 418-427℃.

6. The method for preparing the modified carbon fiber reinforced polyaryl ether ketone composite material according to claim 5, characterized in that, The procedure for mechanically mixing polybenzimidazole dispersion with phosphorus-functionalized carbon fiber is as follows: Under a protective atmosphere, place the phosphorus-functionalized carbon fiber in a high-speed mixer, add the polybenzimidazole dispersion in three to five batches at a speed of 500-1000 rpm, with a total mixing time of 20-80 minutes, and then dry it for later use.

7. The method for preparing the modified carbon fiber reinforced polyaryl ether ketone composite material according to any one of claims 1-6, characterized in that, The preheating temperature of the polyaryletherketone in the molding die is 360-380℃, and the preheating time is 40-100 minutes.

8. The method for preparing the modified carbon fiber reinforced polyaryl ether ketone composite material according to any one of claims 1-6, characterized in that, The stepped molding process is a three-stage molding process, including a preheating stage, a molding stage, and an annealing stage. The preheating section is maintained at 360-380℃ and 8-12MPa pressure for 10-40 minutes. The molding section is heated to 380℃-385℃ and held at 12-20MPa for 5-15 minutes. The annealing section involves slowly cooling the temperature of the forming section to 180-220°C at a cooling rate of 1-3°C / min for annealing for 40-80 minutes.

9. The method for preparing the modified carbon fiber reinforced polyaryl ether ketone composite material according to any one of claims 1-6, characterized in that, The polyaryl ether ketone is selected from one or more of polyether ether ketone, polyether ketone, polyether ketone ketone, polyether ether ketone ketone, and polyether ketone ether ketone ketone.

10. A modified carbon fiber reinforced polyaryl ether ketone composite material, characterized in that, The modified carbon fiber reinforced polyaryl ether ketone composite material is obtained by the preparation method according to any one of claims 1-9.

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