A nanofiller modified polytetrafluoroethylene material and a preparation method thereof

Abstract

This invention relates to the field of polytetrafluoroethylene (PTFE) preparation, specifically to a nanofiller-modified PTFE material and its preparation method. The prepared nanofiller-modified PTFE material is composed of the following substances: 70-85 parts PTFE resin, 0.5-5 parts aminated graphene oxide, 5-10 parts surface-modified silicon carbide nanowires, and Ti3C2T... x The composition includes 0-2 parts MXene nanosheets, 3-6 parts potassium titanate whiskers, 1-2 parts hollow TiO2 nanotubes, 0.3-2 parts coupling agent, and 1-2 parts lubricant. This invention also provides a method for preparing this product. The prepared nanofiller-modified polytetrafluoroethylene composite material exhibits high thermal conductivity, low coefficient of friction, low wear rate per unit area, high heat distortion temperature, and excellent performance. The preparation method is simple, the process conditions are mild, and it is easy to promote and apply.

Description

Technical Field

[0001] This invention relates to the field of polytetrafluoroethylene (PTFE) preparation, specifically to a nanofiller-modified PTFE material and its preparation method. Background Technology

[0002] Polytetrafluoroethylene (PTFE) possesses excellent chemical stability, a low coefficient of friction, and resistance to high and low temperatures, making it widely used in numerous fields such as chemical engineering, machinery, electronics, military, and medical applications. However, PTFE also has some inherent drawbacks, such as low hardness, poor wear resistance, and poor creep resistance. These shortcomings limit its application in situations where high material performance is required.

[0003] Traditional methods for modifying polytetrafluoroethylene (PTFE) include adding glass fibers and carbon fibers. However, these conventional fillers are relatively large, making it difficult to achieve uniform dispersion within the PTFE matrix and potentially compromising the original properties of PTFE. In recent years, the development of nanotechnology has provided new avenues for PTFE modification. Nanofillers possess unique properties such as small size effects and surface effects, enabling the modification of PTFE at the microscale, thereby significantly improving the material's overall performance. However, the application of nanofillers in PTFE still faces some challenges, such as poor compatibility between nanofillers and the PTFE matrix, leading to agglomeration and hindering the full realization of their advantages. Therefore, developing a modification method that effectively solves the dispersion problem of nanofillers and improves their compatibility with the PTFE matrix is ​​of significant practical importance.

[0004] CN109851962B relates to the field of composite material technology, specifically to a graphene-like nano-carbon nitride modified polytetrafluoroethylene (PTFE) friction material, its preparation method, and its application. The provided graphene-like nano-carbon nitride modified PTFE friction material, by mass parts, comprises the following raw materials: 50-80 parts of PTFE; 5-15 parts of polyimide; 5-10 parts of polyphenylene ester; 5-20 parts of aramid pulp; 5-15 parts of potassium titanate whiskers; and 0.5-1.3 parts of graphene-like nano-carbon nitride. The graphene-like nano-carbon nitride modified PTFE friction material prepared using the above-mentioned raw materials exhibits a stable coefficient of friction, a low mass wear rate, and a high conversion efficiency, meeting the requirements for friction materials in ultrasonic motors. However, the formulation uses a relatively large amount of organic matter, and its application areas are not wide-ranging.

[0005] Therefore, it is of great significance to develop a nanofiller-modified polytetrafluoroethylene material and its preparation method that can effectively improve the overall performance of polytetrafluoroethylene. Summary of the Invention

[0006] The present invention relates to a nanofiller-modified polytetrafluoroethylene composite material, which is composed of the following substances in parts by mass:

[0007] 70-85 parts of polytetrafluoroethylene resin

[0008] 0.5–5 parts of aminated graphene oxide

[0009] 5-10 parts of surface-modified silicon carbide nanowires

[0010] Ti3C2T x 0-2 parts of MXene nanosheets

[0011] 3-6 parts of potassium titanate whiskers

[0012] 1-2 parts of hollow TiO2 nanotubes

[0013] Coupling agent 0.3-2 parts

[0014] 1 to 2 parts of lubricant.

[0015] In this invention, potassium titanate whiskers act as a friction modifier to reduce the coefficient of friction, while silicon carbide nanowires serve as the main load-bearing framework to suppress cold flow deformation. Ti3C2T... x MXene nanosheets serve as conductive and thermally conductive bridges, forming a self-lubricating interface layer that enhances the product's wear resistance and thermal conductivity.

[0016] Furthermore, the preparation method of the aminated graphene oxide is as follows: graphene oxide is added to 5 times its mass of ethanol, and then 0.2 times its mass of ethylenediamine is added. Nitrogen gas is then introduced, and the pressure is maintained between 0.1 and 0.15 MPa. The reaction is carried out at 80 to 110°C for 8 to 10 hours. After cooling, filtration, washing, and drying, aminated graphene oxide is obtained. The aminated graphene oxide enhances the interfacial compatibility with polytetrafluoroethylene resin through amino grafting. The amino groups form a hydrogen bond network with the polytetrafluoroethylene resin segments, resulting in better bonding. At the same time, the graphene oxide fragments also have the function of a lubricant, resulting in better performance.

[0017] Furthermore, the preparation method of the surface-modified silicon carbide nanowires is as follows: silicon carbide nanowires are added to an ethanol solution of 5wt% KH-550 at 5 times their mass, refluxed at 80°C for 2 hours, cooled, filtered, washed, and dried to obtain surface-modified silicon carbide nanowires. The surface-modified silicon carbide nanowires not only have good thermal conductivity, but also have good bonding force due to the condensation of surface hydroxyl groups and coupling agents. They also work synergistically with potassium titanate whiskers to withstand multi-directional stress. At the same time, silicon carbide nanowires can bridge cracks and improve fracture resistance.

[0018] Furthermore, the aspect ratio of the potassium titanate whiskers is ≥40:1.

[0019] Furthermore, the coupling agent is a mixture of KH-550 and perfluorooctyltriethoxysilane in a 1:1 mass ratio or 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. When the coupling agent is a mixture of KH-550 and perfluorooctyltriethoxysilane in a 1:1 mass ratio, KH-550 connects the inorganic filler, and perfluorooctyltriethoxysilane is oriented at the polytetrafluoroethylene resin interface to form a Si-O-Si three-dimensional network, reducing the interfacial energy. The mixture contains two different functional groups, one end of which can chemically react with the hydroxyl groups on the surface of the nanofiller, and the other end of which can physically entangle or chemically react with the polytetrafluoroethylene molecular chains, thereby forming a bridge between the nanofiller and the polytetrafluoroethylene body and improving their compatibility. When the coupling agent is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, the ionic liquid replaces silane, possessing both dispersion and lubrication functions. The cationic adsorbs onto the filler surface, while the anionic forms a charge transfer complex with polytetrafluoroethylene, repairing scratches under frictional heat triggering, thus exhibiting self-healing function.

[0020] Furthermore, the hollow TiO2 nanotubes are silver-supported hollow TiO2 nanotubes. Hollow TiO2 nanotubes have a large specific surface area, adsorb polytetrafluoroethylene degradation products, and also have photocatalytic activity to inhibit oil adsorption. In the presence of silver ions, they can also increase the antibacterial effect and extend the product's service life.

[0021] Furthermore, the lubricant is molybdenum disulfide, which can reduce the coefficient of friction and prevent high-temperature agglomeration.

[0022] The present invention also provides a method for preparing the above-mentioned nanofiller-modified polytetrafluoroethylene composite material, comprising the following steps:

[0023] S1. Amminated graphene oxide, surface-modified silicon carbide nanowires, and Ti3C2T x MXene nanosheets, potassium titanate whiskers, silver-supported hollow TiO2 nanotubes, coupling agents and lubricants are mixed in a high-speed mixer, then vacuum dried, and then dried a second time at 200-260℃ under nitrogen for 1-2 hours to obtain mixture A. The second drying can further remove moisture and improve the dispersion properties of mixture A, which is beneficial to the mixing of components in the product.

[0024] S2. After ultrasonically dispersing mixture A, add it together with polytetrafluoroethylene resin into a twin-screw extruder and melt-blend at 180-220°C. The screw speed is 100-150 rpm and the mixing time is 30-50 min to ensure that all components are fully and evenly mixed to obtain mixture B.

[0025] S3. The mixture B is extruded and granulated using an extruder. The granules are then placed in a mold and molded under a pressure of 10–20 MPa. The molding temperature is increased gradually: 260–290℃ for 0.5 h, 290–330℃ for 0.5 h, and 330–370℃ for 1 h. The mixture is then allowed to cool naturally to room temperature to obtain nanofiller-modified polytetrafluoroethylene material. The gradient heating process can make the prepared product more uniform and tougher.

[0026] Furthermore, in step S1, after the materials are mixed in the high-speed mixer, they are ball-milled and then vacuum-dried.

[0027] The nanofiller-modified polytetrafluoroethylene composite material prepared by this invention has high thermal conductivity, low coefficient of friction, low unit wear rate, high heat distortion temperature, excellent performance, simple preparation method, mild process conditions, and is easy to promote and apply. Detailed Implementation

[0028] 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] A nanofiller-modified polytetrafluoroethylene composite material, composed of the following substances:

[0031] 75kg of polytetrafluoroethylene resin

[0032] 2kg of aminated graphene oxide

[0033] Surface-modified silicon carbide nanowires 6kg

[0034] 4 kg of potassium titanate whiskers, aspect ratio 45

[0035] 1 kg of hollow TiO2 nanotubes

[0036] 1 kg of coupling agent

[0037] 1 kg of molybdenum disulfide.

[0038] The preparation method of the aminated graphene oxide is as follows: graphene oxide is added to 5 times its mass of ethanol, and then 0.2 times its mass of ethylenediamine is added. Nitrogen gas is then introduced and the pressure is maintained between 0.11 and 0.13 MPa. The reaction is carried out at 90 to 92°C for 8 hours. After cooling, filtration, washing, and drying, aminated graphene oxide is obtained.

[0039] The preparation method of the surface-modified silicon carbide nanowires is as follows: silicon carbide nanowires are added to an ethanol solution of 5wt% KH-550 at 5 times their mass, refluxed at 80°C for 2 hours, cooled, filtered, washed, and dried to obtain surface-modified silicon carbide nanowires.

[0040] The coupling agent is a mixture of 0.5 kg KH-550 and 0.5 kg perfluorooctyltriethoxysilane.

[0041] The preparation method of the above-mentioned nanofiller-modified polytetrafluoroethylene composite material is characterized by comprising the following steps:

[0042] S1. Aminated graphene oxide, surface-modified silicon carbide nanowires, potassium titanate whiskers, silver-supported hollow TiO2 nanotubes, coupling agent and lubricant are mixed in a high-speed mixer, then vacuum dried, and then dried a second time at 220-230℃ under nitrogen for 1 hour to obtain mixture A.

[0043] S2. After ultrasonically dispersing mixture A, add it together with polytetrafluoroethylene resin into a twin-screw extruder and melt-blend at 200-205°C. The screw speed is 120 rpm and the mixing time is 40 min to ensure that all components are fully and evenly mixed to obtain mixture B.

[0044] S3. The mixture B is extruded and granulated using an extruder. The granules are then placed in a mold and molded under a pressure of 15 MPa. The molding temperature is increased gradually, with a holding pressure of 280℃ for 0.5 h, 310℃ for 0.5 h, and 360℃ for 1 h. The mixture is then naturally cooled to room temperature to obtain nanofiller modified polytetrafluoroethylene material.

[0045] Example 2

[0046] A nanofiller-modified polytetrafluoroethylene composite material, composed of the following substances:

[0047] 75kg of polytetrafluoroethylene resin

[0048] 2kg of aminated graphene oxide

[0049] Surface-modified silicon carbide nanowires 6kg

[0050] Ti3C2T x MXene nanosheets 1kg

[0051] 4 kg of potassium titanate whiskers, aspect ratio 45

[0052] 1 kg of hollow TiO2 nanotubes

[0053] 1 kg of coupling agent

[0054] 1 kg of molybdenum disulfide.

[0055] The preparation method of the aminated graphene oxide is as follows: graphene oxide is added to 5 times its mass of ethanol, and then 0.2 times its mass of ethylenediamine is added. Nitrogen gas is then introduced and the pressure is maintained between 0.11 and 0.13 MPa. The reaction is carried out at 90 to 92°C for 8 hours. After cooling, filtration, washing, and drying, aminated graphene oxide is obtained.

[0056] The preparation method of the surface-modified silicon carbide nanowires is as follows: silicon carbide nanowires are added to an ethanol solution of 5wt% KH-550 at 5 times their mass, refluxed at 80°C for 2 hours, cooled, filtered, washed, and dried to obtain surface-modified silicon carbide nanowires.

[0057] The coupling agent is a mixture of 0.5 kg KH-550 and 0.5 kg perfluorooctyltriethoxysilane.

[0058] The preparation method of the above-mentioned nanofiller-modified polytetrafluoroethylene composite material is characterized by comprising the following steps:

[0059] S1. Amminated graphene oxide, surface-modified silicon carbide nanowires, and Ti3C2T x MXene nanosheets, potassium titanate whiskers, silver-supported hollow TiO2 nanotubes, coupling agents and lubricants were mixed in a high-speed mixer, then vacuum dried, and then dried a second time under nitrogen at 220-230°C for 1 hour to obtain mixture A.

[0060] S2. After ultrasonically dispersing mixture A, add it together with polytetrafluoroethylene resin into a twin-screw extruder and melt-blend at 200-205°C. The screw speed is 120 rpm and the mixing time is 40 min to ensure that all components are fully and evenly mixed to obtain mixture B.

[0061] S3. The mixture B is extruded and granulated using an extruder. The granules are then placed in a mold and molded under a pressure of 15 MPa. The molding temperature is increased gradually, with a holding pressure of 280℃ for 0.5 h, 310℃ for 0.5 h, and 360℃ for 1 h. The mixture is then naturally cooled to room temperature to obtain nanofiller modified polytetrafluoroethylene material.

[0062] Example 3

[0063] A nanofiller-modified polytetrafluoroethylene composite material, composed of the following substances:

[0064] 75kg of polytetrafluoroethylene resin

[0065] 2kg of aminated graphene oxide

[0066] Surface-modified silicon carbide nanowires 6kg

[0067] 4 kg of potassium titanate whiskers, aspect ratio 45

[0068] 1 kg of silver-supported hollow TiO2 nanotubes

[0069] 1 kg of coupling agent

[0070] 1 kg of molybdenum disulfide.

[0071] The preparation method of the aminated graphene oxide is as follows: graphene oxide is added to 5 times its mass of ethanol, and then 0.2 times its mass of ethylenediamine is added. Nitrogen gas is then introduced and the pressure is maintained between 0.11 and 0.13 MPa. The reaction is carried out at 90 to 92°C for 8 hours. After cooling, filtration, washing, and drying, aminated graphene oxide is obtained.

[0072] The preparation method of the surface-modified silicon carbide nanowires is as follows: silicon carbide nanowires are added to an ethanol solution of 5wt% KH-550 at 5 times their mass, refluxed at 80°C for 2 hours, cooled, filtered, washed, and dried to obtain surface-modified silicon carbide nanowires.

[0073] The coupling agent is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0074] The preparation method of the above-mentioned nanofiller-modified polytetrafluoroethylene composite material is characterized by comprising the following steps:

[0075] S1. Aminated graphene oxide, surface-modified silicon carbide nanowires, potassium titanate whiskers, silver-supported hollow TiO2 nanotubes, coupling agent and lubricant are mixed in a high-speed mixer, then vacuum dried, and then dried a second time at 220-230℃ under nitrogen for 1 hour to obtain mixture A.

[0076] S2. After ultrasonically dispersing mixture A, add it together with polytetrafluoroethylene resin into a twin-screw extruder and melt-blend at 200-205°C. The screw speed is 120 rpm and the mixing time is 40 min to ensure that all components are fully and evenly mixed to obtain mixture B.

[0077] S3. The mixture B is extruded and granulated using an extruder. The granules are then placed in a mold and molded under a pressure of 15 MPa. The molding temperature is increased gradually, with a holding pressure of 280℃ for 0.5 h, 310℃ for 0.5 h, and 360℃ for 1 h. The mixture is then naturally cooled to room temperature to obtain nanofiller modified polytetrafluoroethylene material.

[0078] Example 4

[0079] A nanofiller-modified polytetrafluoroethylene composite material, composed of the following substances:

[0080] 75kg of polytetrafluoroethylene resin

[0081] 2kg of aminated graphene oxide

[0082] Surface-modified silicon carbide nanowires 6kg

[0083] Ti3C2T x MXene nanosheets 1kg

[0084] 4 kg of potassium titanate whiskers, aspect ratio 45

[0085] 1 kg of hollow TiO2 nanotubes

[0086] 1 kg of coupling agent

[0087] 1 kg of molybdenum disulfide.

[0088] The preparation method of the aminated graphene oxide is as follows: graphene oxide is added to 5 times its mass of ethanol, and then 0.2 times its mass of ethylenediamine is added. Nitrogen gas is then introduced and the pressure is maintained between 0.11 and 0.13 MPa. The reaction is carried out at 90 to 92°C for 8 hours. After cooling, filtration, washing, and drying, aminated graphene oxide is obtained.

[0089] The preparation method of the surface-modified silicon carbide nanowires is as follows: silicon carbide nanowires are added to an ethanol solution of 5wt% KH-550 at 5 times their mass, refluxed at 80°C for 2 hours, cooled, filtered, washed, and dried to obtain surface-modified silicon carbide nanowires.

[0090] The coupling agent is a mixture of 0.5 kg KH-550 and 0.5 kg perfluorooctyltriethoxysilane.

[0091] The preparation method of the above-mentioned nanofiller-modified polytetrafluoroethylene composite material is characterized by comprising the following steps:

[0092] S1. Amminated graphene oxide, surface-modified silicon carbide nanowires, and Ti3C2T x MXene nanosheets, potassium titanate whiskers, silver-supported hollow TiO2 nanotubes, coupling agents and lubricants were mixed in a high-speed mixer and then ball-milled. After vacuum drying, they were then dried a second time under nitrogen at 220-230°C for 1 hour to obtain mixture A.

[0093] S2. After ultrasonically dispersing mixture A, add it together with polytetrafluoroethylene resin into a twin-screw extruder and melt-blend at 200-205°C. The screw speed is 120 rpm and the mixing time is 40 min to ensure that all components are fully and evenly mixed to obtain mixture B.

[0094] S3. The mixture B is extruded and granulated using an extruder. The granules are then placed in a mold and molded under a pressure of 15 MPa. The molding temperature is increased gradually, with a holding pressure of 280℃ for 0.5 h, 310℃ for 0.5 h, and 360℃ for 1 h. The mixture is then naturally cooled to room temperature to obtain nanofiller modified polytetrafluoroethylene material.

[0095] Comparative Example 1

[0096] The aminated graphene oxide in Example 1 was replaced with graphene oxide, and the rest was the same as in Example 1, so it will not be repeated here.

[0097] Comparative Example 2

[0098] The surface-modified silicon carbide nanowire component in Example 1 was removed, and the rest was the same as in Example 1, so it will not be repeated here.

[0099] Comparative Example 3

[0100] The secondary drying step in step S1 of Example 1 is removed, and the rest is the same as in Example 1, so it will not be described again.

[0101] Comparative Example 4

[0102] The 0.5 kg KH-550 and 0.5 kg perfluorooctyltriethoxysilane components in Example 1 were replaced with 1 kg KH-550. The rest were the same as in Example 1 and will not be repeated here.

[0103] The performance of the nanofiller-modified polytetrafluoroethylene composite materials prepared in the above examples and comparative examples was tested, and the test results are shown in Table 1.

[0104] Table 1 Performance Test Results

[0105]

[0106] Table 1 shows that the nanofiller-modified polytetrafluoroethylene composite materials prepared in Examples 1-4 exhibit high thermal conductivity, low coefficient of friction, low wear rate per unit area, and high heat distortion temperature, demonstrating excellent performance. A comparison of the data from Examples 1 and 2 indicates that Ti3C2T… x MXene nanosheets significantly improve the thermal conductivity of the product. A comparison of data from Examples 1 and 4 shows that the ball milling step improves product performance. Data from Comparative Example 1 indicates that aminated graphene oxide has better technical effects. Data from Comparative Example 2 shows that surface-modified silicon carbide nanowires can improve product performance. Data from Comparative Example 3 shows that secondary drying is beneficial for preparing high-performance products. Data from Comparative Example 4 shows that the synergistic effect of KH-550 and perfluorooctyltriethoxysilane is even better.

Claims

1. A nanofiller-modified polytetrafluoroethylene composite material, characterized in that, Composed of the following substances in parts by mass: 70-85 parts of polytetrafluoroethylene resin 0.5-5 parts of aminated graphene oxide 5-10 parts of surface-modified silicon carbide nanowires Ti3C2T x MXene nanoplatelets 0-2 parts 3-6 parts of potassium titanate whiskers 1-2 parts of hollow TiO2 nanotubes 0.3 to 2 parts of coupling agent 1-2 parts lubricant; The preparation method of the aminated graphene oxide is as follows: graphene oxide is added to 5 times its mass of ethanol, and then 0.2 times its mass of ethylenediamine is added. Nitrogen gas is then introduced and the pressure is maintained between 0.1 and 0.15 MPa. The reaction is carried out at 80 to 110°C for 8 to 10 hours. The mixture is then cooled, filtered, washed, and dried to obtain the aminated graphene oxide. The preparation method of the surface-modified silicon carbide nanowires is as follows: silicon carbide nanowires are added to an ethanol solution of 5wt% KH-550 at 5 times their mass, refluxed at 80°C for 2 hours, cooled, filtered, washed, and dried to obtain surface-modified silicon carbide nanowires. The coupling agent is a mixture of KH-550 and perfluorooctyltriethoxysilane in a mass ratio of 1:1 or 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; The preparation method of the nanofiller-modified polytetrafluoroethylene composite material includes the following steps: S1. Amminated graphene oxide, surface-modified silicon carbide nanowires, and optionally Ti3C2T x MXene nanosheets, potassium titanate whiskers, hollow TiO2 nanotubes, coupling agents and lubricants are mixed in a high-speed mixer, then vacuum dried, and then a second drying is carried out at 200~260℃ under nitrogen for 1~2h to obtain mixture A. The second drying can further remove moisture from mixture A and improve dispersion performance, which is beneficial to the mixing of components. S2. After ultrasonically dispersing mixture A, add it together with polytetrafluoroethylene resin into a twin-screw extruder and melt-blend at 180~220℃, with a screw speed of 100~150 rpm and a mixing time of 30~50 min, so that the components are fully mixed and homogeneous to obtain mixture B; S3. The mixture B is extruded and granulated using an extruder. The granules are then placed in a mold and molded under a pressure of 10-20 MPa. The molding temperature is increased gradually, with the following conditions: 260-290℃ for 0.5 h, 290-330℃ for 0.5 h, and 330-370℃ for 1 h. The mixture is then naturally cooled to room temperature to obtain nanofiller-modified polytetrafluoroethylene material.

2. The nanofiller-modified polytetrafluoroethylene composite material according to claim 1, characterized in that, The aspect ratio of the potassium titanate whiskers is ≥40:

1.

3. The nanofiller-modified polytetrafluoroethylene composite material according to claim 1, characterized in that, The hollow TiO2 nanotubes are silver nanotubes supported on hollow TiO2 nanotubes.

4. The nanofiller-modified polytetrafluoroethylene composite material according to claim 1, characterized in that, The lubricant is molybdenum disulfide.

5. The preparation method according to claim 1, characterized in that, In step S1, after the materials are mixed in the high-speed mixer, they are ball-milled and then vacuum dried.

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