High-strength and high-toughness polyamide composite material and preparation method thereof

Abstract

The application belongs to the technical field of polymer materials, and particularly relates to a high-strength and high-toughness polyamide composite material and a preparation method thereof. The composite material comprises the following components in parts by weight: 80-100 parts of long-chain semi-aromatic polyamide, 20-30 parts of oxidized carbon fiber, 10-20 parts of toughening agent, 5-10 parts of ethylene-acrylic acid ionomer, 1-3 parts of pentaerythritol-based polyol, and 1-6 parts of processing aid. The application adds a certain amount of ethylene-acrylic acid ionomer and pentaerythritol-based polyol in a long-chain semi-aromatic polyamide-oxidized carbon fiber reinforced system. During the melt blending process, the two modifiers of ethylene-acrylic acid ionomer and pentaerythritol-based polyol form an active layer rich in polar functional groups on the surface of the oxidized carbon fiber, improve the interfacial interaction between the polyamide and the filler, and solve the problem that the strength and toughness of the polyamide composite material in the prior art are difficult to be considered simultaneously.

Description

A high-strength and high-toughness polyamide composite material and its preparation method Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a high-strength and high-toughness polyamide composite material and its preparation method. Background Technology

[0002] Metallic materials, polymeric materials, composite materials, and inorganic non-metallic materials have become the four pillar materials of modern society. Metallic materials, due to their mature production processes, superior comprehensive performance, and abundant resources, possess strong vitality and are therefore widely used. However, non-metallic materials, with their unique properties, are developing rapidly, gradually replacing some metallic materials in certain fields, and even showing a trend of exceeding the usage of metallic materials in some specialized areas. Polymeric materials, in particular, are basically composed of organic polymer compounds and possess advantages such as light weight, good insulation, stable chemical properties, and multiple molding methods. The multiplicity of the long-chain structure of polymeric compounds endows polymeric materials with various special properties. People can use various means to modify the structure at different levels to produce products with desired properties. Among them, engineering plastics, with their advantages of high specific strength, low density, good thermal and electrical properties, good chemical corrosion resistance, and ease of processing and molding, have become one of the indispensable new materials in modern industry, especially in high-tech industries. In recent years, with the rapid development of the automotive transportation industry, the electronics and information industry, the machinery and instrument industry, and cutting-edge defense technologies such as aerospace, the production, processing, and application of engineering plastics have also been gradually strengthened. Polyamide is one of the most important engineering plastics, ranking first in production volume among the five major general-purpose engineering plastics.

[0003] However, polyamides have lower strength and toughness compared to metallic materials, limiting their further applications. Existing technologies typically modify them to improve the performance of composite materials. Polyamide modification is mainly divided into physical modification and chemical modification. Chemical modification refers to preparing high-performance polyamides through internal chemical reactions within the blend. Chemical modification methods mainly include block copolymerization, graft copolymerization, and crosslinking. Physical modification refers to mechanical blending, which has become the main approach for developing new polymer materials. However, during the blending process, the high interfacial tension between the two substances can lead to poor compatibility of the blended system. Physical modification methods are simple and easy to implement, making them a suitable modification method for widespread application. Chinese invention patent CN120699428A discloses a carbon fiber-glass bead synergistic reinforced PA56 / PPO composite material and its preparation method. By combining modified carbon fibers and silane-modified glass microspheres, the amount of single carbon fiber material added can be reduced, achieving weight reduction while lowering costs. The toughening agent has good compatibility with the matrix resin, and its addition to the PA56 / PPO system produces a better toughness modification effect. Simultaneously, the added compatibilizer can improve the interfacial effect between components, effectively improving the mechanical properties and antistatic properties of the composite material. The carbon fiber-glass bead synergistic reinforced PA56 / PPO composite material provided by this invention exhibits balanced rigidity, toughness, and antistatic properties, making it suitable for use in automotive electronic and electrical products requiring high strength, high toughness, and antistatic properties. However, the above modification method not only has a complex preparation process but also offers limited performance improvement, restricting the further promotion and application of polyamides. Summary of the Invention

[0004] In view of this, the present invention provides a high-strength and high-toughness polyamide composite material and its preparation method. The composite material not only has high strength, but also excellent impact resistance, thus solving the problem that it is difficult to balance strength and toughness in existing polyamide composite materials.

[0005] The present invention solves the above-mentioned technical problems by means of the following technical solution:

[0006] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0007] 80-100 parts of long-chain semi-aromatic polyamide, 20-30 parts of oxidized carbon fiber, 10-20 parts of toughening agent, 5-10 parts of ethylene-acrylic acid ionomer, 1-3 parts of pentaerythritol-based polyol, and 1-6 parts of processing aid.

[0008] In one embodiment, the long-chain semi-aromatic polyamide is one or more of polyamide 9T, polyamide 9I, polyamide 10T, polyamide 10I, polyamide 11T, polyamide 11I, polyamide 12T, polyamide 12I, polyamide 14T, polyamide 14I, polyamide 16T, polyamide 16I, polyamide 18T, and polyamide 18I. Specifically, the long-chain semi-aromatic polyamide in the polyamide composite material is 85-95 parts, specifically 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, or 95 parts. An appropriate amount of long-chain semi-aromatic polyamide can fully exert its connecting effect and promote filler dispersion, thereby better improving the mechanical properties of the material.

[0009] Long-chain semi-aromatic polyamides incorporate both long aliphatic segments and aromatic rings into the polyamide chain. Compared to traditional aliphatic polyamides, the presence of aromatic rings results in higher heat distortion temperatures and greater mechanical strength. Compared to short-chain semi-aromatic polyamides, the long aliphatic chains are flexible "soft segments," endowing the material with good impact toughness and elasticity, overcoming the inherent brittleness of short-chain semi-aromatic polyamides. Furthermore, long-chain semi-aromatic polyamides typically have lower melting points than short-chain semi-aromatic polyamides, resulting in more suitable melt viscosity and easier processing.

[0010] However, simple long-chain semi-aromatic polyamides still cannot meet the requirements of applications with high mechanical performance, such as mechanical equipment. Glass fiber and carbon fiber are common modified fillers for polyamides. Compared to glass fiber, carbon fiber has both higher strength and toughness, and is usually used as a reinforcing and toughening filler for polyamides. However, carbon fiber has poor compatibility with polar resins such as polyamides. Although introducing oxygen-containing functional groups on the surface of carbon fiber through oxidative modification can improve the compatibility between carbon fiber and polyamide resin to some extent, the interfacial force between carbon fiber and polyamide remains low due to the inherent inertness of carbon fiber.

[0011] To this end, this invention adds a certain amount of ethylene-acrylic acid ionomer and pentaerythritol-based polyol. The nonpolar ethylene segments in the ethylene-acrylic acid ionomer have a certain physical compatibility with the long aliphatic chain portion of the polyamide, allowing them to intertwine. Meanwhile, the carboxylic acid groups or ionic clusters can generate strong hydrogen bonds or ion-dipole interactions with the oxygen-containing functional groups on the surface of the oxidized carbon fiber. During melt blending, the ethylene-acrylic acid ionomer can migrate and accumulate at the interface between the carbon fiber and the polyamide, forming a transition layer that effectively reduces the interfacial energy between the two phases and the contact angle of the melt on the fiber surface, allowing the polyamide melt to better encapsulate the fiber. The pentaerythritol-based polyol, with its high functionality and symmetrical molecular structure, can form a dense hydrogen bond network or initiate cross-linking in the interfacial region during melt processing by having its hydroxyl groups form with the amino or carboxyl groups at the ends of the polyamide chain, as well as with the oxygen-containing functional groups in the oxidized carbon fiber and the ethylene-acrylic acid ionomer. This not only improves the thermal stability of the toughening agent and the ethylene-acrylic acid ionomer but also enhances the strength of the interfacial phase. Two modifiers, ethylene-acrylic acid ionomer and pentaerythritol-based polyol, together form an active layer rich in polar functional groups on the surface of oxidized carbon fibers. This active layer firmly binds the carbon fibers through physical interactions and chemical bonds, and also tightly bonds with the polyamide matrix through chain entanglement and chemical bonds. From the polar carbon fiber surface to the interfacial layer rich in polar interactions, and then to the semi-polar polyamide matrix, a gradient transition in modulus and polarity is formed, avoiding abrupt changes in performance. When the material is subjected to external forces, the load can be efficiently transferred from the relatively weak matrix to the high-strength fibers through the strong interface, allowing the fibers to fully bear the load.

[0012] In one embodiment, the preparation process of the oxidized carbon fiber is as follows: carbon fiber is placed in a strong oxidizing acid, ultrasonically reacted for a period of time, and then washed and dried to obtain oxidized carbon fiber. Specifically, the carbon fiber is cleaned before oxidation modification. Further, the amount of oxidized carbon fiber used is 22-28 parts. Specifically, it can be 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, or 28 parts. An appropriate amount of oxidized carbon fiber can both construct a reinforcing network and avoid the technical problem of uneven dispersion caused by excessive oxidized carbon fiber.

[0013] In one embodiment, the strong oxidizing acid is one or more of concentrated nitric acid or concentrated sulfuric acid. In particular, concentrated nitric acid with a concentration of 50-70 wt.% can be selected.

[0014] In one embodiment, the ultrasonic reaction temperature is 40-60°C and the ultrasonic reaction time is 1-2 hours.

[0015] In one embodiment, the toughening agent is one or more of the following: maleic anhydride-grafted polystyrene, maleic anhydride-grafted polyphenylene ether, maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene octene copolymer, maleic anhydride-grafted ethylene propylene diene monomer (EPDM) rubber, and maleic anhydride-grafted SEBS. Further, the amount of toughening agent used is 12-18 parts. Specifically, it can be 12, 13, 14, 15, 16, 17, or 18 parts. An appropriate amount of toughening agent can achieve both reinforcement and toughening effects.

[0016] In one embodiment, the ethylene-acrylate ionomer is saline resin. Specifically, saline resin 9320 can be selected. The ethylene-acrylate ionomer also has a strong toughening effect. Furthermore, the amount of ethylene-acrylate ionomer can be 6-8 parts. An appropriate amount of ethylene-acrylate ionomer can not only fully exert the toughening effect, but also avoid cross-linking catalysis caused by excessive dosage.

[0017] In one embodiment, the pentaerythritol-based polyol is one or more of pentaerythritol mono-, di-, and tri-pentaerythritol. As a small molecule filler, the amount of pentaerythritol-based polyol used should not be excessive; otherwise, it is prone to migrating to the surface during processing, which is detrimental to filler dispersion and the improvement of composite material properties.

[0018] In one embodiment, the processing aid is one or more of coupling agents, lubricants, antioxidants, flow modifiers, release agents, plasticizers, and heat stabilizers.

[0019] On the other hand, the present invention also provides a method for preparing a high-strength and high-toughness polyamide composite material, comprising the following steps:

[0020] (1) Mix long-chain semi-aromatic polyamide, toughening agent, ethylene-acrylic acid ionomer, pentaerythritol-based polyol and processing aid evenly to obtain a mixture;

[0021] (2) The mixture is added into the twin-screw extruder from the main feed port, and the carbon oxidized carbon fiber is added into the twin-screw extruder from the side feed port. The mixture is then extruded and granulated to obtain a high-strength and high-toughness polyamide composite material.

[0022] In one embodiment, the twin-screw extruder has a screw speed of 200-500 r / min and an extrusion temperature of 250-350°C.

[0023] Beneficial effects:

[0024] This invention adds a certain amount of ethylene-acrylic acid ionomer and pentaerythritol-based polyol to a long-chain semi-aromatic polyamide-oxidized carbon fiber reinforced system. During melt blending, the ethylene-acrylic acid ionomer can migrate and accumulate at the interface between the carbon fiber and the polyamide, forming a transition layer that effectively reduces the interfacial energy between the two phases and the contact angle of the melt on the fiber surface, allowing the polyamide melt to better encapsulate the fiber. Meanwhile, the pentaerythritol-based polyol can form a dense cross-linked network with the polyamide chains and the oxygen-containing functional groups in the oxidized carbon fiber and the ethylene-acrylic acid ionomer, enhancing the strength of the interfacial phase. The two modifiers, ethylene-acrylic acid ionomer and pentaerythritol-based polyol, together form an active layer rich in polar functional groups on the surface of the oxidized carbon fiber. This active layer firmly binds the carbon fiber through physical action and chemical bonds, and also tightly bonds it to the polyamide matrix through chain segment entanglement and chemical bonds. When the material is subjected to external force, the load can be efficiently transferred from the relatively weak matrix to the high-strength fiber through the strong interface, allowing the fiber to fully bear the load. Detailed Implementation

[0025] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0026] Unless otherwise specified, the raw material types and preparation processes used in the following examples and comparative examples are the same.

[0027] Specifically, the preparation method of the high-strength and high-toughness polyamide composite material includes the following steps:

[0028] (1) Mix long-chain semi-aromatic polyamide, toughening agent, ethylene-acrylic acid ionomer, pentaerythritol-based polyol and processing aid evenly to obtain a mixture;

[0029] (2) The mixture is added to the twin-screw extruder through the main feed port, and the oxidized carbon fiber (or carbon fiber) is added to the twin-screw extruder through the side feed port. The mixture is extruded and granulated to obtain a high-strength and high-toughness polyamide composite material. The screw speed of the twin-screw extruder is 400 r / min and the extrusion temperature is 320℃.

[0030] The specific preparation process of oxidized carbon fiber is as follows: carbon fiber is placed in 65wt% concentrated nitric acid, ultrasonically reacted at 50℃ for 1.5h, and then washed and dried to obtain oxidized carbon fiber.

[0031] Under the same conditions, the high-strength and high-toughness polyamide composite materials prepared in each embodiment and comparative example were prepared into standard specimens, and their tensile strength (refer to ISO 527), flexural strength (refer to ISO 178) and notched impact strength (refer to ISO 179) were tested respectively.

[0032] Example 1

[0033] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0034] The composition consists of 80 parts of long-chain semi-aromatic polyamide 10T, 20 parts of oxidized carbon fiber, 10 parts of toughening agent (maleic anhydride-grafted SEBS), 5 parts of saline resin 9320, 1 part of dipentaerythritol, and processing aids (0.5 parts of antioxidant 1010, 0.5 parts of coupling agent KH550, and 0.5 parts of lubricant calcium stearate). Tested results show a tensile strength of 214 MPa, a flexural strength of 256 MPa, and a notched impact strength of 12.5 kJ / m. 2 .

[0035] Example 2

[0036] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0037] The composition consists of 100 parts of long-chain semi-aromatic polyamide 10T, 28 parts of oxidized carbon fiber, 20 parts of toughening agent (maleic anhydride-grafted ethylene-octene copolymer), 9 parts of saline resin 9320, 3 parts of dipentaerythritol, and processing aids (2 parts of antioxidant 1010, 2 parts of coupling agent KH550, and 2 parts of lubricant zinc stearate). Testing revealed a tensile strength of 221 MPa, a flexural strength of 271 MPa, and a notched impact strength of 13.4 kJ / m. 2 .

[0038] Example 3

[0039] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0040] The composition consists of 90 parts of long-chain semi-aromatic polyamide 10T, 30 parts of oxidized carbon fiber, 15 parts of toughening agent (maleic anhydride-grafted ethylene-octene copolymer), 8 parts of saline resin 9320, 2 parts of dipentaerythritol, and processing aids (1.5 parts of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). Testing revealed a tensile strength of 232 MPa, a flexural strength of 274 MPa, and a notched impact strength of 12.9 kJ / m. 2 .

[0041] Example 4

[0042] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0043] The composition consists of 82 parts of long-chain semi-aromatic polyamide 10T, 27 parts of oxidized carbon fiber, 11 parts of toughening agent (maleic anhydride-grafted SEBS), 8.5 parts of saline resin 9320, 1.2 parts of dipentaerythritol, and processing aids (0.5 parts of antioxidant 1010, 2 parts of coupling agent KH550, and 1.8 parts of lubricant PTFE). Tested results show a tensile strength of 237 MPa, a flexural strength of 272 MPa, and a notched impact strength of 14.1 kJ / m. 2 .

[0044] Example 5

[0045] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0046] The composition consists of 90 parts of long-chain semi-aromatic polyamide 10T, 25 parts of oxidized carbon fiber, 15 parts of toughening agent (maleic anhydride-grafted ethylene-octene copolymer), 10 parts of saline resin 9320, 2 parts of dipentaerythritol, and processing aids (1.5 parts of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). Testing revealed a tensile strength of 219 MPa, a flexural strength of 264 MPa, and a notched impact strength of 13.6 kJ / m. 2 .

[0047] Example 6

[0048] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0049] The composition consists of 85 parts of long-chain semi-aromatic polyamide 10T, 23 parts of oxidized carbon fiber, 13 parts of toughening agent (maleic anhydride-grafted ethylene-octene copolymer), 6 parts of saline resin 9320, 1.5 parts of dipentaerythritol, and processing aids (0.8 parts of antioxidant 1010, 1.2 parts of coupling agent KH550, and 1.1 parts of lubricant talc). Testing revealed a tensile strength of 226 MPa, a flexural strength of 275 MPa, and a notched impact strength of 13.5 kJ / m. 2 .

[0050] Example 7

[0051] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0052] The composition consists of 95 parts of long-chain semi-aromatic polyamide 10T, 25 parts of oxidized carbon fiber, 18 parts of toughening agent (maleic anhydride-grafted SEBS), 7 parts of saline resin 9320, 2.5 parts of dipentaerythritol, and processing aids (1.5 parts of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant calcium stearate). Tested results show a tensile strength of 231 MPa, a flexural strength of 282 MPa, and a notched impact strength of 14.2 kJ / m. 2 .

[0053] Example 8

[0054] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0055] The composition includes 92 parts of long-chain semi-aromatic polyamide 10T, 26 parts of oxidized carbon fiber, 14 parts of toughening agent (maleic anhydride-grafted ethylene-octene copolymer), 7.5 parts of saline resin 9320, 2.2 parts of dipentaerythritol, and processing aids (1.6 parts of antioxidant 1010, 1.3 parts of coupling agent KH550, and 1.7 parts of lubricant polytetrafluoroethylene). Tested results show a tensile strength of 227 MPa, a flexural strength of 267 MPa, and a notched impact strength of 13.8 kJ / m. 2 .

[0056] Example 9

[0057] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0058] The composition consists of 90 parts of long-chain semi-aromatic polyamide 10T, 25 parts of oxidized carbon fiber, 15 parts of toughening agent (maleic anhydride-grafted ethylene-octene copolymer), 8 parts of saline resin 9320, 2 parts of dipentaerythritol, and processing aids (1.5 parts of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). Testing revealed a tensile strength of 236 MPa, a flexural strength of 284 MPa, and a notched impact strength of 14.6 kJ / m. 2 .

[0059] Comparative Example 1

[0060] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0061] The composition consists of 90 parts of long-chain semi-aromatic polyamide 10T, 25 parts of oxidized carbon fiber, 15 parts of toughening agent (maleic anhydride-grafted ethylene-octene copolymer), 0 parts of saline resin 9320, 10 parts of dipentaerythritol, and processing aids (1.5 parts of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). The tensile strength is 201 MPa, the flexural strength is 248 MPa, and the notched impact strength is 9.8 kJ / m. 2 .

[0062] Comparative Example 2

[0063] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0064] The composition consists of 90 parts of long-chain semi-aromatic polyamide 10T, 25 parts of oxidized carbon fiber, 15 parts of toughening agent (maleic anhydride-grafted ethylene-octene copolymer), 10 parts of saline resin 9320, 0 parts of dipentaerythritol, and processing aids (1.5 parts of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). The tensile strength is 186 MPa, the flexural strength is 225 MPa, and the notched impact strength is 12.1 kJ / m. 2 .

[0065] Comparative Example 3

[0066] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0067] The composition consists of 90 parts of long-chain semi-aromatic polyamide 10T, 25 parts of oxidized carbon fiber, 15 parts of toughening agent (maleic anhydride-grafted ethylene-octene copolymer), 2 parts of saline resin 9320, 8 parts of dipentaerythritol, and processing aids (1.5 parts of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). Testing revealed a tensile strength of 194 MPa, a flexural strength of 233 MPa, and a notched impact strength of 10.6 kJ / m. 2 .

[0068] Comparative Example 4

[0069] A high-strength, high-toughness polyamide composite material, comprising the following components in parts by weight:

[0070] The composition consists of 90 parts of long-chain semi-aromatic polyamide 10T, 25 parts of carbon fiber, 15 parts of toughening agent (maleic anhydride-grafted ethylene-octene copolymer), 8 parts of saline resin 9320, 2 parts of dipentaerythritol, and processing aids (1.5 parts of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). Testing revealed a tensile strength of 183 MPa, a flexural strength of 227 MPa, and a notched impact strength of 9.7 kJ / m. 2 .

[0071] As can be seen from the above examples and comparative examples, the addition of ethylene-acrylic acid ionomer and pentaerythritol-based polyol promotes the interfacial interaction between oxidized carbon fiber and long-chain semi-aromatic polyamide. During melt blending, the ethylene-acrylic acid ionomer can migrate and accumulate at the interface between carbon fiber and polyamide, forming a transition layer that effectively reduces the interfacial energy between the two phases and the contact angle of the melt on the fiber surface, allowing the polyamide melt to better encapsulate the fiber. Meanwhile, the pentaerythritol-based polyol, with its high functionality and symmetrical molecular structure, can form a dense hydrogen bond network with polyamide, oxidized carbon fiber, and ethylene-acrylic acid ionomer or initiate cross-linking in the interfacial region during melt processing. This not only improves the thermal stability of the toughening agent and the ethylene-acrylic acid ionomer but also enhances the strength of the interfacial phase.

[0072] Specifically, compared to Example 9, Comparative Examples 1-2 lacked ethylene-acrylic acid ionomer and pentaerythritol-based polyol, respectively, resulting in reduced interfacial interaction between oxidized carbon fibers and long-chain semi-aromatic polyamides, leading to decreased strength and toughness of the composite material. In Comparative Example 3, the amount of ethylene-acrylic acid ionomer was too small, while the amount of pentaerythritol-based polyol was too large. As a small molecule filler, excessive use of pentaerythritol-based polyol can easily lead to surface migration during processing, which is detrimental to filler dispersion and improvement of composite material performance. Comparative Example 4 shows that the surface of pure carbon fibers is inert and lacks active groups, making it unable to interact with ethylene-acrylic acid ionomer and pentaerythritol-based polyol through chemical bonds. The molten long-chain semi-aromatic polyamide has poor wettability on carbon fibers, failing to fully spread and encapsulate them, easily forming tiny voids and defects at the interface. When the material is under stress, the load cannot be effectively transferred from the matrix to the high-strength, high-modulus carbon fibers, causing the resin matrix to yield or break.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-strength, high-toughness polyamide composite material, characterized in that, It contains the following components in parts by weight: 80-100 parts of long-chain semi-aromatic polyamide, 20-30 parts of oxidized carbon fiber, 10-20 parts of toughening agent, 5-10 parts of ethylene-acrylic acid ionomer, 1-3 parts of pentaerythritol-based polyol, and 1-6 parts of processing aid.

2. The high-strength, high-toughness polyamide composite material as described in claim 1, characterized in that, The long-chain semi-aromatic polyamide is one or more of polyamide 9T, polyamide 9I, polyamide 10T, polyamide 10I, polyamide 11T, polyamide 11I, polyamide 12T, polyamide 12I, polyamide 14T, polyamide 14I, polyamide 16T, polyamide 16I, polyamide 18T, and polyamide 18I.

3. The high-strength, high-toughness polyamide composite material as described in claim 1, characterized in that, The process for preparing the oxidized carbon fiber is as follows: carbon fiber is placed in a strong oxidizing acid, subjected to ultrasonic reaction for a period of time, and then washed and dried to obtain oxidized carbon fiber.

4. The high-strength, high-toughness polyamide composite material as described in claim 3, characterized in that, The strong oxidizing acid is one or more of concentrated nitric acid or concentrated sulfuric acid.

5. The high-strength, high-toughness polyamide composite material as described in claim 1, characterized in that, The toughening agent is one or more of the following: maleic anhydride-grafted polystyrene, maleic anhydride-grafted polyphenylene ether, maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene octene copolymer, maleic anhydride-grafted ethylene propylene diene monomer (EPDM) rubber, and maleic anhydride-grafted SEBS.

6. The high-strength, high-toughness polyamide composite material as described in claim 1, characterized in that, The ethylene-acrylic acid ionomer is Salin resin 9320; the pentaerythritol-based polyol is one or more of pentaerythritol, dipentaerythritol, and tripentaerythritol.

7. The high-strength, high-toughness polyamide composite material as described in claim 1, characterized in that, The processing aid is one or more of the following: coupling agent, lubricant, antioxidant, flow modifier, release agent, plasticizer, and heat stabilizer.

8. The method for preparing a high-strength, high-toughness polyamide composite material as described in claim 1, characterized in that, The process includes the following steps: (1) mixing long-chain semi-aromatic polyamide, toughening agent, ethylene-acrylic acid ionomer, pentaerythritol-based polyol and processing aid evenly to obtain a mixture; (2) adding the mixture into a twin-screw extruder from the main feed port, and adding carbon oxidized carbon fiber into the twin-screw extruder from the side feed port, and extruding and granulating to obtain a high-strength and high-toughness polyamide composite material.

9. The method for preparing a high-strength, high-toughness polyamide composite material as described in claim 8, characterized in that, The screw speed of the twin-screw extruder is 200-500 r / min.

10. The method for preparing a high-strength, high-toughness polyamide composite material as described in claim 8, characterized in that, The extrusion temperature is 250-350℃.