Carbon fiber / graphene composite nylon modifier, preparation method and application thereof

Abstract

This invention discloses a carbon fiber / graphene composite nylon modifier, its preparation method, and its application. The modifier comprises a matrix composed of chopped carbon fibers and graphene bonded to its surface; the graphene is bonded to the carbon fiber surface through partial thermal decomposition products of polyvinyl butyral. The preparation method includes: providing a solution of polyvinyl butyral; mixing it with chopped carbon fibers and graphene, and kneading the mixture to obtain a modifier precursor; and performing an annealing treatment to cause partial thermal decomposition of the polyvinyl butyral to obtain the carbon fiber / graphene composite nylon modifier. This invention uses polyvinyl butyral as a connecting unit between graphene and carbon fibers, and welds them through partial pyrolysis at high temperatures. Using it as a nylon modifier improves the thermal and electrical conductivity pathways between carbon fibers, graphene, and nylon, facilitating rapid heat and charge transfer, and significantly improving mechanical properties.

Description

Technical Field

[0001] This invention application relates to the field of polymer material modification technology, and in particular to a carbon fiber / graphene composite nylon modifier, its preparation method and application. Background Technology

[0002] With the increasing integration of electronic devices, the miniaturization and weight reduction of components, and the higher speed and power of electronic components, heat is becoming more concentrated inside the devices, affecting their accuracy and lifespan. Effective thermal management of materials can ensure the reliable operation of functional devices. Therefore, higher requirements are placed on the thermal conductivity and mechanical properties of polymer materials. Developing functional plastics that combine good mechanical, electrical, and thermal conductivity has significant economic and practical value.

[0003] Graphene possesses high thermal conductivity, electrical conductivity, specific surface area, and mechanical properties. Theoretically, it can be used to modify engineering plastics to achieve high thermal conductivity, high electrical conductivity, high strength, and lightweight properties. However, in practical applications, using a single graphene material to construct a continuous heat transfer network to improve the thermal or electrical conductivity of polymer materials usually leads to a decrease in mechanical properties. Therefore, finding a way to balance the improvement of high thermal conductivity, electrical conductivity, and mechanical strength in graphene-modified polymer materials has always been an important development direction for graphene functionalized composite materials.

[0004] Carbon fibers, with their continuous structure and anisotropic characteristics, can not only exert their mechanical load-bearing capacity but also construct interconnected heat transport networks between carbon fibers, graphene, and polymer layers. By modifying the surfaces of graphene and carbon fibers, the interfacial properties of fillers can be improved, enhancing the compatibility between carbon fibers and the resin matrix and strengthening the interfacial bonding of composite materials. This helps to construct a thermally and electrically conductive interconnected network between the polymer matrix, improving the interfacial thermal resistance, contact resistance, and stress transmission between graphene, carbon fibers, and the resin matrix. Consequently, the thermal conductivity, electrical properties, and strength of the composite material are simultaneously enhanced.

[0005] In existing technologies, Chinese invention patents CN114921952A and CN113293605A use graphene oxide sizing agents to modify the surface and interface of carbon fibers to enhance the interfacial properties, interfacial shear strength, and interlaminar shear strength of carbon fiber composites. Chinese invention patent CN105862428A uses graphene and graphene oxide to modify carbon fibers with epoxy resin to improve interlaminar shear strength. However, these patents do not involve improving the thermal and electrical conductivity of the modified materials, and the surface-treated resin is not further treated but only used for auxiliary reinforcement, which may have an adverse effect on the electrical and thermal conductivity of the materials. Furthermore, they do not explain the application performance of injection-molded polymer resin materials.

[0006] Other existing technologies, such as Chinese invention patent CN109265986A, use carbon fiber and graphene to be blended and composited separately. The thermal conductivity is 2.1 W / m·k, and the tensile strength is only 55 MPa, which is obviously low and has great potential for improvement. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a carbon fiber / graphene composite nylon modifier, its preparation method and application.

[0008] To achieve the aforementioned objectives, the technical solution adopted in this invention application includes:

[0009] In a first aspect, the present invention provides a carbon fiber / graphene composite nylon modifier, comprising a matrix composed of short-cut carbon fibers and graphene bonded to the surface of the carbon fibers.

[0010] The graphene is bonded to the surface of the carbon fiber via some thermal decomposition products of polyvinyl butyral.

[0011] Secondly, the present invention also provides a method for preparing a carbon fiber / graphene composite nylon modifier, comprising:

[0012] Provide a solution of polyvinyl butyral;

[0013] The solution was mixed with chopped carbon fibers and graphene, and the mixture was kneaded to obtain a modifier precursor.

[0014] The modifier precursor is annealed to cause a partial thermal decomposition reaction of the polyvinyl butyral, and the graphene is bonded to the surface of the short-cut carbon fiber through the thermal decomposition products to obtain a carbon fiber / graphene composite nylon modifier.

[0015] Thirdly, the present invention also provides a method for preparing a composite nylon material, comprising:

[0016] The above-mentioned carbon fiber / graphene composite nylon modifier and selected additives are used to blend and modify nylon to obtain composite nylon materials.

[0017] Fourthly, the present invention also provides composite nylon materials prepared by the preparation method.

[0018] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention include:

[0019] The technical solution provided by this invention uses polyvinyl butyral as the connecting unit for graphene and carbon fiber. Under high-temperature treatment, the graphene and carbon fiber are welded through partial pyrolysis of polyvinyl butyral, providing good interfacial compatibility. It is used as a modifier for nylon, forming an interpenetrating structure that effectively inhibits the aggregation of the two fillers, resulting in a highly dispersed, highly exfoliated composite material with nanoscale dispersion. This improves the thermal and electrical conductivity pathways between carbon fiber, graphene, and nylon, facilitating rapid heat and charge transfer, and significantly improving the mechanical properties of the composite material.

[0020] The above description is merely an overview of the technical solution of the present invention. In order to enable those skilled in the art to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described below. Detailed Implementation

[0021] In current technologies, graphene / carbon fiber nylon composite modified nylon materials involve surface modification of several materials and then granulation with nylon to construct a polymer matrix. However, the thermal and electrical conductivity between these materials and the strength is often significantly unbalanced, indicating a large potential for improvement in the thermal and electrical conductivity interconnect network.

[0022] In view of the shortcomings of the prior art, the inventors of this invention have proposed the technical solution of the present invention through long-term research and extensive practice.

[0023] The main concept of this technical solution is to use polyvinyl butyral (PVB) as a composite modifier for graphene and carbon fiber. Graphene and carbon fiber are welded under high temperature treatment, and the welded material is used as a modifier for nylon. By adding other auxiliary materials such as modified silanol, polar polyester lubricant, toughening agent, and antioxidant, the composite material is obtained through twin-screw extrusion granulation, thereby overcoming the problems existing in the above-mentioned prior art.

[0024] The following will provide a further explanation of the technical solution, its implementation process, and its principles.

[0025] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0026] The first aspect of the present invention provides a carbon fiber / graphene composite nylon modifier, comprising a matrix composed of chopped carbon fibers and graphene bonded to the surface of the carbon fibers.

[0027] The graphene is bonded to the surface of the carbon fiber via some thermal decomposition products of polyvinyl butyral.

[0028] In the above technical solutions, the graphene can be mechanically exfoliated graphene or graphene prepared by CVD. The graphene can be directly purchased or made in-house. Similarly, the chopped carbon fibers used can be selected from commercially available materials or can be purchased and cut into finished carbon fibers for self-manufacturing.

[0029] In some embodiments, the mass ratio of graphene to chopped carbon fibers is preferably 1:10-5:1, the length of the chopped carbon fibers is 5-25 mm, and the size of the graphene is 0.1-5000 μm with a thickness of 0.5-10 nm.

[0030] The second aspect of this invention provides a method for preparing a carbon fiber / graphene composite nylon modifier, comprising the following steps:

[0031] A solution of polyvinyl butyral is provided.

[0032] The solution was mixed with chopped carbon fibers and graphene, and the mixture was kneaded to obtain a modifier precursor.

[0033] The modifier precursor is annealed to cause a partial thermal decomposition reaction of the polyvinyl butyral, and the graphene is bonded to the surface of the short-cut carbon fiber through the thermal decomposition products to obtain a carbon fiber / graphene composite nylon modifier.

[0034] In some embodiments, the mixture can be kneaded and then granulated, with the resulting particles used as precursors for the modifier.

[0035] In some implementations, the kneading process is carried out at a temperature of 10-70°C for 5-30 minutes.

[0036] In some embodiments, the concentration of polyvinyl butyral in the solution can be 10-200 g / L.

[0037] In some embodiments, the viscosity of the polyvinyl butyral can be 3-50 seconds, more preferably 3-10 seconds.

[0038] In some embodiments, the ratio of the polyvinyl butyral solution to the total mass of the chopped carbon fibers and graphene is 10-250 g / kg, and the concentration of the polyvinyl butyral solution can be 10-200 g / L.

[0039] In some embodiments, the temperature of the thermal decomposition reaction can be 180-220°C, the time can be 5-60 min, more preferably 5-15 min, or the time can be controlled such that the mass thermal weight loss is 0.5%-5%.

[0040] In some embodiments, the thermal decomposition reaction is preferably carried out in a protective atmosphere.

[0041] A third aspect of the present invention provides a method for preparing a composite nylon material, comprising the following steps:

[0042] The carbon fiber / graphene composite nylon modifier provided by any of the above embodiments or prepared by the above preparation method, along with selected additives, are used to blend and modify nylon to obtain a composite nylon material.

[0043] As some typical application examples of the above technical solutions, the composite nylon material provided by the present invention can be prepared using the following preparation process:

[0044] (1) Prepare an ethanol solution of polyvinyl butyral (PVB), slowly add it to the initial mixture of graphene and short-cut carbon fibers, perform pre-dispersion treatment using a kneading device, and then extrude and granulate it at room temperature (usually 15-30℃) using a single screw extruder and dry it.

[0045] (2) The composite particles pre-dispersed and dried in the first step are decomposed by high temperature treatment to decompose part of the PVB. During this process, the partially decomposed PVB products weld graphene and carbon fiber together, while the undecomposed PVB molecular chain segments remain connected to the above decomposition products, forming a unique microstructure of one welding point (PVB pyrolysis product) and three connecting materials (undecomposed PVB molecular chain segments, graphene, and short-cut carbon fiber). The retained PVB molecular chain segments can also interact with additives or nylon molecules in the preparation of composite nylon, thereby further improving the overall performance.

[0046] (3) Use it as a modifier for nylon. By adding coupling agents, toughening agents, lubricants, antioxidants and other selected additives, high thermal conductivity, electrical conductivity and high strength composite functional plastic masterbatch is prepared by twin-screw granulation equipment, which is also a composite nylon material.

[0047] Of course, the solvents for dissolving PVB are not limited to ethanol; any organic solvent that can dissolve this type of polymer and is volatile can achieve the above-mentioned technical effects.

[0048] In some embodiments, the selected additives may include, for example, any one or a combination of two or more of coupling agents, toughening agents, lubricants, and antioxidants.

[0049] In some embodiments, the blending modification method may include, but is not limited to, twin-screw extrusion. Other blending modification methods, such as roll extrusion, are also applicable to the modification of nylon materials, as long as they can achieve the function of blending modification.

[0050] In some embodiments, the coupling agent may include modified silanol.

[0051] In some embodiments, the coupling agent preferably includes polyether-modified terminal hydroxyl silanol.

[0052] As some specific implementation examples, the solid content (weight fraction) of the polyvinyl butyral in ethanol is 10-15%. The ratio of graphene to carbon fiber is 1:1. The pre-dispersion treatment time in the kneading equipment is 15 min. The high-temperature annealing treatment temperature is 210°C, and the treatment time is 10 min. The coupling agent is modified silanol, more preferably polyether-modified hydroxyl-terminated silanol. The toughening agent can be selected as maleic anhydride-grafted polyethylene wax, for example, Mitsui HI-WAX1105A. The lubricant can be selected as, for example, polar polyester wax MJU WAX 7902. The antioxidant can be selected as, for example, a composite of two antioxidants, 1010 and 168. The nylon is preferably PA6 with a viscosity of about 2.0.

[0053] Through long-term practice, the inventors have also discovered that the coupling agent is preferably polyether-modified terminal hydroxyl silanol, which can interact with some segments of incompletely pyrolyzed polyvinyl butyral to further improve the high dispersibility of the filler in the polymer matrix, and ultimately further enhance the comprehensive performance of the composite material.

[0054] However, the specific examples described above are merely demonstrations of a common selection from the numerous optional raw materials of this invention, and do not represent that this invention is only applicable to the aforementioned selections. Clearly, the main inventive concept of this invention lies in forming a special carbon fiber-graphene welded structure as described above through specific polymer materials and high-temperature treatment under certain conditions, thereby bringing about the excellent comprehensive performance of the composite nylon material. Regarding the selection of nylon materials and various selected auxiliary materials, except for the coupling agent, which has a further impact on the comprehensive performance, the selection of other auxiliary materials and main materials can be achieved by replacing common auxiliary materials. Equivalent replacement of all auxiliary materials with the same function can achieve comparable technical effects.

[0055] A fourth aspect of the present invention provides a composite nylon material prepared by the method for preparing nylon composite materials provided in any of the above embodiments.

[0056] In some embodiments, the tensile strength of the composite nylon material is 90-180 MPa.

[0057] In some embodiments, the notched impact strength of the composite nylon material is 4.5-9 J / m. 2 .

[0058] In some embodiments, the surface resistivity of the composite nylon material is 0.1-150Ω.

[0059] In some embodiments, the thermal conductivity of the composite nylon material is 2-10 W / m·K.

[0060] The technical solution of the present invention will be further described in detail below through several embodiments. However, the selected embodiments are only used to illustrate the present invention and do not limit the scope of the present invention. The following embodiments are merely further explanations of the present invention and do not represent that the scope of protection of the present invention is limited thereto. All equivalent substitutions made according to the ideas of the present invention are within the scope of the present invention.

[0061] Unless otherwise specified, the processing temperature in this invention is room temperature. Regarding the specific source of the raw materials, the graphene used was prepared in-house using common existing techniques. The preparation process is as follows:

[0062] First, a polyvinylpyrrolidone ethanol solution of a certain concentration is prepared. Then, 80-mesh expanded graphite is dispersed into the solution, wherein the weight (mass) ratio of expanded graphite, polyvinylpyrrolidone, and water is 6:0.3:93.7, and the temperature is 40℃. The mixed solution is dispersed and sheared in a colloid mill for 50 minutes to obtain a graphite dispersion. The dispersion is then processed in a ball mill for 2 hours at a speed of 300 r / min, and then homogenized using a microfluidic jet for 2 hours at a pressure of 200 MPa to obtain a graphene-modified ethanol dispersion. Finally, the dispersion is subjected to pressure filtration and drying to obtain few-layer graphene.

[0063] All other raw materials and reagents were commercially purchased.

[0064] The carbon fiber short fibers are Toray T700 from Japan.

[0065] The surface coupling agent is modified silanol, polyether-modified hydroxyl-terminated silanol, Momentive Advanced Materials (China) Co., Ltd.

[0066] The toughening agent is maleic anhydride-grafted polyethylene wax, model number Mitsui HI-WAX1105A.

[0067] The lubricant is a polar polyester wax, model MJU WAX 7902.

[0068] The antioxidants are 168 and 1010.

[0069] The nylon materials are PA6, PA66, PA46, and PA1010.

[0070] Example 1

[0071] This embodiment illustrates the preparation and testing process of the composite nylon modifier and the modified composite nylon material, as detailed below:

[0072] 1) Preparation of the modifier: Prepare a 1 kg 15% polyvinyl butyral (PVB, viscosity 3-10 seconds) ethanol solution as a graphene and carbon fiber composite modifier. Add it to a kneader containing 10 kg of graphene and carbon fiber (mass ratio 1:1) and knead for 15 min. Granulate by single-screw extrusion at room temperature and vacuum dry. Treat at 210℃ for 15 min under nitrogen atmosphere to weld the graphene and carbon fiber together as a nylon modifier, denoted as "Composite A".

[0073] 2) Based on the above-mentioned "composite A" modifier, composite nylon materials are prepared using a twin-screw extrusion process. The specific twin-screw extrusion granulation process is as follows:

[0074] The twin-screw extruder contains 6-10 zones, with the following temperatures and screw speeds for each zone: Zone 1: 165-225°C; Zone 2: 170-230°C; Zone 3: 175-235°C; Zone 4: 180-265°C; Zone 5: 180-270°C; Zone 6: 180-275°C; Die head: 180-275°C, and so on; Screw speed: 200-350 rpm. After air-cooling and pelletizing, graphene / carbon fiber composite nylon modified engineering plastic is obtained.

[0075] 3) The above-mentioned composite nylon material was tested for electrical conductivity, thermal conductivity, and mechanical strength. The testing instruments and methods used are as follows:

[0076] Conductivity testing instrument: Four-probe tester, RTS-8, Guangzhou Four-Probe Technology Co., Ltd.

[0077] Thermal conductivity test method: ASTM D5470 (heat flow method), DRL-III heat flow thermal conductivity meter, Xiangtan Xiang Instrument Co., Ltd.

[0078] Tensile strength test standard: ISO 527.

[0079] Notched impact strength test standard: ISO 179.

[0080] Furthermore, for the sake of full understanding, the raw materials used in this embodiment, their mass proportions, and the test results are listed in Table 1 below.

[0081] Example 2

[0082] This embodiment still describes the preparation and testing process of the composite nylon modifier and the modified composite nylon material, as detailed below:

[0083] A 1 kg solution of 15% polyvinyl butyral (PVB, viscosity 3-10 seconds) in ethanol was prepared as a graphene and carbon fiber composite modifier. This solution was added to a kneader containing 5 kg of graphene and carbon fiber (mass ratio 1:2) and kneaded for 10 min. The mixture was then granulated by single-screw extrusion at room temperature and vacuum dried. After treatment at 210℃ for 10 min under a nitrogen atmosphere, the graphene and carbon fiber were welded together to serve as a modifier for nylon, denoted as "Composite B".

[0084] The preparation and testing of the composite nylon material are largely the same as those in Example 1. The main difference is that the proportions used in preparing the composite nylon material have been adjusted. Specific details and test results are shown in Table 1 below.

[0085] Example 3

[0086] This embodiment is still the same as the preparation process of the composite nylon modifier and composite nylon material in Example 1. The main difference is that the specific raw material selection and ratio have been adjusted, as shown in Table 1 below.

[0087] The thermal conductivity, electrical conductivity and mechanical strength testing methods used are exactly the same as those in Example 1, and the test results are listed in Table 1 below.

[0088] Example 4

[0089] This embodiment is still the same as the preparation process of the composite nylon modifier and composite nylon material in Example 2. It is largely the same as Example 1, except that the specific raw material selection and ratio are adjusted, as shown in Table 1 below.

[0090] The thermal conductivity, electrical conductivity and mechanical strength testing methods used are exactly the same as those in Example 1, and the test results are listed in Table 1 below.

[0091] Comparative Example 1

[0092] The preparation process of the composite nylon modifier and composite nylon material in this comparative example is shown below:

[0093] 1) Preparation of composite nylon modifier: The raw material ratio is the same as in Example 1, but graphene and carbon fiber are not combined in any way. Instead, they are directly blended together and used as composite nylon modifier.

[0094] The preparation and testing processes for the remaining composite nylons using twin-screw extruders were completely consistent with those in Example 1.

[0095] Furthermore, for the sake of full understanding, the raw materials used in this comparative example, their mass proportions, and the test results are also listed in Table 1 below.

[0096] Comparative Example 2

[0097] The preparation process of the composite nylon modifier and composite nylon material in this comparative example is shown below:

[0098] 1) Preparation of composite nylon modifier: The raw material ratio is the same as in Example 2, but graphene and carbon fiber are not combined in any way. Instead, they are directly blended together and used as composite nylon modifier.

[0099] The preparation and testing process of the remaining composite nylon twin-screw extruders were completely consistent with that in Example 2.

[0100] Furthermore, for the sake of full understanding, the raw materials used in this comparative example, their mass proportions, and the test results are also listed in Table 1 below.

[0101] Comparative Example 3

[0102] The preparation process of the composite nylon modifier and composite nylon material in this comparative example is shown below:

[0103] 1) Preparation of composite nylon modifier: The raw material ratio is the same as in Example 1, but the difference is that the high-temperature annealing step is not performed, and the granulated particles after kneading are used directly as composite nylon modifier.

[0104] The preparation and testing processes for the remaining composite nylons using twin-screw extruders were completely consistent with those in Example 1.

[0105] Furthermore, for the sake of full understanding, the raw materials used in this comparative example, their mass proportions, and the test results are also listed in Table 1 below.

[0106] Comparative Example 4

[0107] The preparation process of the composite nylon modifier and composite nylon material in this comparative example is shown below:

[0108] 1) Preparation of composite nylon modifier: The raw material ratio is the same as in Example 1, but the difference is that during high-temperature annealing, the temperature is adjusted to 300°C and the time is extended to 1 hour to ensure that the composite polyvinyl butyral is completely pyrolyzed rather than partially pyrolyzed.

[0109] The preparation and testing processes for the remaining composite nylons using twin-screw extruders were completely consistent with those in Example 1.

[0110] Furthermore, for the sake of full understanding, the raw materials used in this comparative example, their mass proportions, and the test results are also listed in Table 1 below.

[0111] Comparative Example 5

[0112] This comparative example demonstrates the preparation process of a composite nylon modifier and composite nylon material. The modifier used is "Composite A" prepared in Example 1. The difference lies in the selection of additives in the preparation of the composite nylon modification, as detailed below:

[0113] 2) Preparation of composite nylon modifier: The proportion of main raw materials is the same as in Example 1, but the difference is that the coupling agent is replaced with other common coupling agents, namely a silane coupling agent, specifically named 3-aminopropyltriethoxysilane, commercially known as KH550.

[0114] The preparation and testing processes for the remaining composite nylons using twin-screw extruders were completely consistent with those in Example 1.

[0115] Furthermore, for the sake of full understanding, the raw materials used in this comparative example, their mass proportions, and the test results are also listed in Table 1 below.

[0116] Table 1. Raw material composition and properties of composite nylon materials in Examples 1-4 and Comparative Examples 1-2

[0117]

[0118]

[0119] As can be seen from the data in Examples 1-2 and Comparative Examples 1-2 in Table 1, using polyvinyl butyral (PVB) as a composite modifier for graphene and carbon fiber, and then welding graphene and carbon fiber together, and using it as a modifier for nylon 6, can significantly improve the thermal conductivity of the composite material by nearly double. It also significantly improves the tensile strength of the composite material. The data in Examples 3-4 show that modifying nylon 66 with carbon fiber / graphene welding material can also yield composite materials with good performance, and the composite materials also maintain good notched impact strength.

[0120] Furthermore, the comparison between Example 1 and Comparative Example 3 shows that the modification effect obtained by the "welding" treatment with appropriate high-temperature annealing is greater than that without welding. Comparative Examples 4 and 5 show that the partial thermal decomposition structure brought about by appropriate welding temperature and time, combined with the selected coupling agent, can further improve the overall performance.

[0121] Example 5

[0122] The preparation process of the composite nylon modifier and composite nylon material in this comparative example is largely the same as that in Example 1, with the main difference being:

[0123] In step 1), during the preparation of the composite nylon modifier, the mass ratio of graphene to chopped carbon fiber is 1:10; the viscosity of polyvinyl butyral is about 50 seconds, and its mass fraction in the solution is 20%; the kneading time is 6 minutes; and the high-temperature annealing temperature is 180°C for 10 minutes.

[0124] The remaining steps are the same as in Example 1.

[0125] The composite nylon material obtained in this embodiment produces the same technical effect as that in Example 1, with a tensile strength of 180 MPa and a notched impact strength of 7.3 J / m. 2 The surface resistivity is 15Ω and the thermal conductivity is 2.1W / m·k, which are significant improvements compared to the unmodified implementation and the implementation of independent mixing of graphene and carbon fiber.

[0126] Example 6

[0127] The preparation process of the composite nylon modifier and composite nylon material in this comparative example is largely the same as that in Example 1, with the main difference being:

[0128] In step 1), during the preparation of the composite nylon modifier, the mass ratio of graphene to chopped carbon fiber is 5:1; the viscosity of polyvinyl butyral is about 30 seconds, and its mass fraction in the solution is 2%; the kneading time is 15 minutes; and the high-temperature annealing temperature is 220°C for 5 minutes.

[0129] The remaining steps are the same as in Example 1.

[0130] The composite nylon material obtained in this embodiment produces the same technical effect as that in Example 1, with a tensile strength of 110 MPa and a notched impact strength of 4.7 J / m. 2 The surface resistivity is 220Ω and the thermal conductivity is 5.1W / m·k, which are significant improvements compared to the unmodified implementation and the implementation of independent mixing of graphene and carbon fiber.

[0131] Based on the above embodiments and comparative examples, it is clear that the technical solution provided by the embodiments of the present invention uses polyvinyl butyral as the connecting unit of graphene and carbon fiber. Under high temperature treatment, graphene and carbon fiber are welded by partial pyrolysis of polyvinyl butyral, which is used as a modifier for nylon. This improves the thermal and electrical conductivity pathways between carbon fiber, graphene and nylon, which can help the rapid transfer of heat and charge, and can also significantly improve the mechanical properties of composite materials.

[0132] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be used to limit the scope of protection of the present invention.

[0133] All references to this invention are incorporated herein by reference as if each reference were individually incorporated herein by reference. Furthermore, it is understood that after reading the foregoing teachings of this invention, those skilled in the art may make various modifications or alterations to this invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0134] All equivalent changes or modifications made in accordance with the spirit and essence of this invention shall be covered within the scope of protection of this invention.

Claims

1. A carbon fiber / graphene composite nylon modifier characterized by, It includes a matrix composed of chopped carbon fibers and graphene bonded to the surface of the chopped carbon fibers. The graphene is bonded to the surface of the carbon fiber via partial thermal decomposition products of polyvinyl butyral; the preparation method of the carbon fiber / graphene composite nylon modifier includes: Provide a solution of polyvinyl butyral; The solution was mixed with chopped carbon fibers and graphene, and the mixture was kneaded to obtain a modifier precursor. The modifier precursor is annealed to cause a partial thermal decomposition reaction of the polyvinyl butyral, and the graphene is bonded to the surface of the short-cut carbon fiber through the thermal decomposition products to obtain a carbon fiber / graphene composite nylon modifier. The thermal decomposition reaction is carried out at a temperature of 180-220°C for 5-60 minutes, or the thermal decomposition reaction time is controlled to be such that the mass thermal weight loss is 0.5%-5%.

2. The carbon fiber / graphene composite nylon modifier of claim 1, wherein, The mass ratio of graphene to chopped carbon fiber is 1:10-5:1, the length of the chopped carbon fiber is 5-25 mm, and the size of the graphene is 0.1-5000 μm with a thickness of 0.5-10 nm.

3. A method for preparing a carbon fiber / graphene composite nylon modifier, characterized in that, include: Provide a solution of polyvinyl butyral; The solution was mixed with chopped carbon fibers and graphene, and the mixture was kneaded to obtain a modifier precursor. The modifier precursor is annealed to cause a partial thermal decomposition reaction of the polyvinyl butyral, and the graphene is bonded to the surface of the short-cut carbon fiber through the thermal decomposition products to obtain a carbon fiber / graphene composite nylon modifier. The thermal decomposition reaction is carried out at a temperature of 180-220°C for 5-60 minutes, or the thermal decomposition reaction time is controlled to be such that the mass thermal weight loss is 0.5%-5%.

4. The preparation method according to claim 3, characterized in that, After kneading the mixture, it is granulated, and the resulting particles are used as the precursor of the modifier. The kneading process is carried out at a temperature of 10-70℃ for 5-30 minutes.

5. The preparation method according to claim 3, characterized in that, The mass fraction of polyvinyl butyral in the solution is 1-20%; And / or, the viscosity of the polyvinyl butyral is 3-50 seconds; And / or, the ratio of the polyvinyl butyral solution to the total mass of the chopped carbon fibers and graphene is 10-250 g / kg, and the concentration of the polyvinyl butyral solution is 10-200 g / L.

6. A method of making a composite nylon material, characterized by, include: The carbon fiber / graphene composite nylon modifier described in any one of claims 1-2 and selected additives are used to blend and modify nylon to obtain a composite nylon material.

7. The preparation method according to claim 6, characterized in that, The selected additives include any one or a combination of two or more of coupling agents, toughening agents, lubricants, and antioxidants; And / or, the method of blending modification includes twin-screw extrusion.

8. The preparation method according to claim 7, characterized in that, The coupling agent includes modified silanol.

9. The production method according to claim 8, characterized by, The coupling agent includes polyether-modified terminal hydroxyl silanol.

10. A composite nylon material prepared by any one of claims 6-9.

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