Polytetrafluoroethylene composite material filled with superfine molybdenum-oxygen nano material as well as preparation method and application of polytetrafluoroethylene composite material

Abstract

The invention relates to the technical field of nano composite materials, in particular to a polytetrafluoroethylene composite material filled with a superfine molybdenum oxide nano material as well as a preparation method and application of the polytetrafluoroethylene composite material. According to the invention, the ultrafine molybdenum-oxygen nano material and polytetrafluoroethylene are mixed, sieved, molded and sintered to obtain the polytetrafluoroethylene composite material filled with the ultrafine molybdenum-oxygen nano material; according to the invention, the superfine molybdenum oxide nano material is used as a raw material and is filled in polytetrafluoroethylene, so that on one hand, the superfine molybdenum oxide nano material has the advantage of fine size and can be uniformly dispersed in ethanol; on the other hand, the superfine molybdenum oxide nano material can be mixed with PTFE in ethyl alcohol, the performance of the obtained product is stable and controllable, and the tribological performance and the mechanical performance of the polytetrafluoroethylene composite material are remarkably improved through the nano size advantage of the reinforcement superfine molybdenum oxide nano material; the technical defects existing in the nanometer material filling process in the prior art are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of nanocomposites, and particularly to a polytetrafluoroethylene composite filled with ultrafine molybdenum oxide nanomaterials, a preparation method thereof, and an application thereof. Background Art

[0002] Polytetrafluoroethylene (PTFE), as a high-performance special engineering plastic, is often used in the aerospace field. PTFE has become one of the high-performance special engineering plastics with the largest consumption in the aerospace field, especially aerospace sealing materials. Due to its special chemical structure, PTFE exhibits excellent physical and chemical properties, specifically: stable chemical properties (acid resistance, alkali resistance, strong oxidant resistance, organic solvent resistance), aging resistance, and excellent high and low temperature resistance, making it an ideal sealing material.

[0003] PTFE products are formed by molding and sintering fine PTFE powder particles. Because there are voids between PTFE powder particles during the molding process and the viscosity of the PTFE melt is extremely high and difficult to flow, void defects exist in the sintered PTFE, thus reducing the mechanical properties of PTFE; in addition, the PTFE molecular chains are prone to sliding relative to each other and are easily peeled off under friction, so the wear resistance is poor; and due to the special chemical structure of PTFE, the load-bearing capacity of PTFE is poor, which limits the application of PTFE as a sealing material in the sealing field.

[0004] In order to improve the mechanical properties, wear resistance, or load-bearing capacity of PTFE, PTFE is often modified. The modification of PTFE is divided into three categories: blending modification, surface modification, and filling modification. Among them, filling modification is widely used in the modification of PTFE because it is simple to operate and most effective. In filling modification, nanomaterials have become one of the preferred methods for filling and modifying PTFE due to their small size, large specific surface area, and easy dispersion.

[0005] In the prior art of filling and modifying PTFE with nanomaterials, the technical difficulties mainly lie in the mixing process. Specifically: generally, nanomaterials with a width of several hundred nanometers are used for filling, and since the filling material is an inorganic material, it is difficult to disperse in the liquid phase. Either surface treatment is required, which is not only costly but also cumbersome; or the nanomaterials and PTFE are mechanically mixed, but due to the large amount of heat generated by the high-speed rotating blades, agglomeration of PTFE particles and / or nanomaterials occurs, resulting in insufficient and uneven mixing of the final obtained mixture, and further leading to poor and unstable product performance. Summary of the Invention

[0006] In view of the deficiencies in the above-mentioned prior art, the present invention provides a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials, a preparation method and an application thereof. The present invention adopts ultrafine molybdenum oxide nanomaterials and polytetrafluoroethylene, and mixes, sieves, molds and then sinters to obtain a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials; the present invention uses ultrafine molybdenum oxide nanomaterials as raw materials and fills them in polytetrafluoroethylene. On the one hand, due to the advantage of small size, the ultrafine molybdenum oxide nanomaterials can be evenly dispersed in ethanol; on the other hand, the ultrafine molybdenum oxide nanomaterials can be mixed with PTFE in ethanol, and the performance of the obtained product is stable and controllable. Thanks to the nanometer size advantage of the ultrafine molybdenum oxide nanomaterials of the reinforcement, the tribological properties and mechanical properties of the polytetrafluoroethylene composite material are significantly improved, thereby overcoming the technical defects existing in the nanomaterial filling process of the prior art.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The preparation method of the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial comprises the following steps:

[0009] Ultrafine molybdenum oxide nanomaterials are dispersed in a solvent, and then polytetrafluoroethylene is added, mixed, and dried to obtain a mixture. The mixture is sequentially broken up, sieved, molded, and then sintered to obtain a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials.

[0010] Wherein, the ultrafine molybdenum oxygen nanomaterial is selected from ultrafine molybdenum oxygen nanowires, ultrafine molybdenum oxygen nanoquantum dots or ultrafine molybdenum oxygen nanosheets.

[0011] Preferably, in the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial, the mass percentage of ultrafine molybdenum oxide nanomaterial is 5wt% to 50wt%. If it is lower than 5wt%, the performance of the polytetrafluoroethylene composite material will be generally improved. If it is higher than 50wt%, the cost will increase. In general, the filling modification should not exceed 50wt%.

[0012] Preferably, the molding conditions are: maintaining the pressure at 30-40 MPa for 4-5 minutes. If the pressure is too low, there will be vacancies and defects inside the blank; if the pressure is too high, the internal stress of the blank will be too high, and the blank will crack. The purpose of maintaining the pressure is to ensure that the air inside the blank is removed as much as possible to reduce the pores, and to ensure the strength of the blank.

[0013] Preferably, the sintering and forming conditions are as follows: heating from room temperature to 330 °C, holding at 330 °C for 1 - 2 h; heating from 330 °C to 370 - 380 °C, holding at 370 - 380 °C for 1 - 2 h; cooling from 370 - 380 °C to 330 °C, holding at 330 °C for 1 - 2 h and then cooling to room temperature. Since PTFE has poor thermal conductivity, too fast heating and cooling rates will cause too large temperature difference inside PTFE and result in thermal stress. Therefore, hold for a period of time near the melting point (327 °C) of PTFE to ensure that PTFE has as few internal cracking problems caused by thermal stress as possible during sintering. Holding at 370 - 380 °C is to ensure that the PTFE material is fully melted during sintering, improve the sintering degree of PTFE, and improve the tribological properties and mechanical properties of the polytetrafluoroethylene composite filled with ultrafine molybdenum oxide nanomaterials.

[0014] Preferably, a 100 - mesh sieve is used for sieving. First, the larger the mesh number of the sieve, the smaller the aperture of the sieve, and vice versa, the smaller the mesh number, the larger the aperture. Greater than 100 meshes means that the aperture of the sieve is getting smaller and the sieved powder is finer. However, the size of the mechanically dispersed mixture powder can only be reduced to a certain extent. Therefore, powders cannot be sieved when the mesh number is too large.

[0015] Preferably, the ultrafine molybdenum oxide nanowires are prepared according to the following steps:

[0016] Add a glycine solution and an acid solution to an ammonium molybdate solution, and obtain ultrafine molybdenum oxide nanowires through a hydrothermal reaction.

[0017] Among them, the molar ratio of ammonium molybdate to glycine is 1:30 - 40, and the molar ratio of ammonium molybdate to the acid in the acid solution is 1:225 - 250. At this ratio, ultrafine molybdenum oxide nanowires can be successfully and stably prepared.

[0018] Preferably, the ultrafine molybdenum oxide nanodots are prepared according to the following steps:

[0019] Add a thiomalic acid solution and an acid solution to an ammonium molybdate solution, mix evenly and then spray - dry to obtain ultrafine molybdenum oxide nanodots.

[0020] Among them, the mass ratio of ammonium molybdate to thiomalic acid is 1:0.1 - 0.2, and the molar ratio of ammonium molybdate to the acid in the acid solution is 1:8 - 10. At this ratio, ultrafine molybdenum oxide nanodots can be successfully and stably prepared.

[0021] Preferably, the ultrafine molybdenum oxide nanosheets are prepared according to the following steps:

[0022] Add oleylamine and oleic acid to an ammonium molybdate solution, and obtain ultrafine molybdenum oxide nanosheets through a hydrothermal reaction;

[0023] Among them, the mass-volume ratio of the ammonium molybdate solution is 40-50 g / L, and the volume ratio of the ammonium molybdate solution, oleylamine and oleic acid is 2:2:5.

[0024] The present invention also protects a polytetrafluoroethylene composite material filled with the ultrafine molybdenum oxide nanomaterial prepared by the above preparation method.

[0025] Preferably, in the polytetrafluoroethylene composite material filled with the ultrafine molybdenum oxide nanomaterial, the width of the ultrafine molybdenum oxide nanowire is 10-20 nm, the particle size of the ultrafine molybdenum oxide nanodot is 1-5 nm, and the particle size of the ultrafine molybdenum oxide nanosheet is 100-200 nm.

[0026] The present invention also protects the application of the polytetrafluoroethylene composite material filled with the ultrafine molybdenum oxide nanomaterial in the preparation of special engineering plastics.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. In the present invention, the ultrafine molybdenum oxide nanomaterial is filled into polytetrafluoroethylene to obtain a polytetrafluoroethylene composite material filled with the ultrafine molybdenum oxide nanomaterial. The reason for filling with molybdenum oxide compounds is that molybdenum oxide compounds have excellent chemical and physical properties, making them widely used and highly adjustable; the change in the oxidation state of molybdenum elements allows the control of crystal structure and morphology, thus obtaining molybdenum oxide compounds with different structural sizes. Due to the extremely small size advantage of the ultrafine molybdenum oxide nanomaterial, the ultrafine molybdenum oxide nanomaterial can be filled in the voids of PTFE, reducing the pore defects of the PTFE composite material, thereby improving the mechanical properties of PTFE products. In addition, the ultrafine molybdenum oxide nanomaterial can act as an "anchor point" to anchor the polytetrafluoroethylene molecular chains, thereby enhancing the interaction between the polytetrafluoroethylene molecular chains and improving the wear resistance of polytetrafluoroethylene. Therefore, the present invention provides a polytetrafluoroethylene composite material filled with the ultrafine molybdenum oxide nanomaterial and its preparation method.

[0029] In addition, in the present invention, the ultrafine molybdenum oxide nanomaterial is used as the raw material. Due to the size advantage of the ultrafine molybdenum oxide nanomaterial, it can be well dispersed in ethanol, thus well solving the problem that the filling material is difficult to disperse in the liquid phase; in addition, the liquid-phase mixing method is adopted to prevent the problem of powder agglomeration caused by the heat generated during the mechanical mixing process. Therefore, using the ultrafine molybdenum oxide nanomaterial as the filling material for polytetrafluoroethylene overcomes the technical barriers in the preparation method and effectively improves the product performance.

[0030] 2. The present invention provides a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials. Using ammonium molybdate as the molybdenum source, ultrafine molybdenum oxide nanomaterials are obtained. The ultrafine molybdenum oxide nanomaterials are dissolved in ethanol and stirred and mixed with PTFE powder, dried, dispersed, and sieved. Finally, the polytetrafluoroethylene composite material is obtained by molding and sintering. In the preparation method provided by the present invention, since the ultrafine molybdenum oxide nanomaterials can be dissolved in ethanol, the ultrafine molybdenum oxide nanomaterials and polytetrafluoroethylene powder are fully mixed under liquid-phase mixing conditions.

[0031] 3. The polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials provided by the present invention has a more uniform mixture obtained by liquid-phase mixing compared with the traditional mechanical mixing of PTFE composites. The polytetrafluoroethylene composite material obtained after molding and sintering has fewer pore defects, so its performance is better. In addition, the ultrafine molybdenum oxide nanomaterials are simple to prepare, have low energy consumption, large output, fast production speed, and controllable cost, and are easy to be mass-produced industrially. Brief Description of the Drawings

[0032] Figure 1 Among them, (a) is the TEM image of ultrafine molybdenum oxide nanowires, (b) is the TEM image of ultrafine molybdenum oxide nanosheets, and (c) is the TEM image of ultrafine molybdenum oxide nanodots.

[0033] Figure 2 This is the SEM image and the EDS mapping spectra of F, O, and Mo elements of the ultrafine molybdenum oxide nanomaterials and PTFE powder after molding in Example 2 of the present invention.

[0034] Figure 3 This is the SEM image and the EDS mapping spectra of F, O, and Mo elements of the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials in Example 2 of the present invention.

[0035] Figure 4 This is the XRD pattern of the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials in Example 2 of the present invention.

[0036] Figure 5 Among them, (a) is the test chart of the compressive mechanical properties of the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials and polytetrafluoroethylene in Example 2 of the present invention, and (b) is the compressive elastic modulus chart.

[0037] Figure 6 This is the reciprocating friction and wear test chart of the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials and polytetrafluoroethylene in Example 2 of the present invention.

[0038] Figure 7 This is the scanning electron microscope image of the wear debris obtained after the reciprocating friction and wear of polytetrafluoroethylene.

[0039] Figure 8SEM image of wear debris obtained after reciprocating friction and wear of PTFE composite filled with ultrafine molybdenum oxide nanomaterials in Example 2 of the present invention.

[0040] Figure 9 In (A), the figure shows the volume wear of PTFE composites filled with different nickel-titanium particles; in (B), the figure shows the compressive elastic modulus of PTFE composites filled with different nickel-titanium particles. Detailed implementation manners

[0041] The following describes the detailed implementation manners of the present invention in detail, but it should be understood that the protection scope of the present invention is not limited by the detailed implementation manners. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0042] A preparation method of a PTFE composite filled with ultrafine molybdenum oxide nanomaterials includes the following steps:

[0043] The ultrafine molybdenum oxide nanomaterials are selected from ultrafine molybdenum oxide nanowires or ultrafine molybdenum oxide nanodots or ultrafine molybdenum oxide nanosheets.

[0044] The ultrafine molybdenum oxide nanowires are prepared as follows: Using ammonium molybdate and glycine as raw materials, synthesizing ultrafine molybdenum oxide nanowires in an acidic aqueous solution; wherein, the molar ratio of ammonium molybdate to glycine is 1:30 - 40, the molar ratio of ammonium molybdate to hydrochloric acid is 1:225 - 250, and the reaction conditions are 180 °C for 12 h.

[0045] The ultrafine molybdenum oxide nanodots are prepared as follows: Using ammonium molybdate and thiomalic acid as raw materials, synthesizing ultrafine molybdenum oxide nanodots in an acidic aqueous solution; wherein, the mass ratio of ammonium molybdate to thiomalic acid is 1:0.1 - 0.2, the molar ratio of ammonium molybdate to hydrochloric acid is 1:8 - 10, and spray drying is used for preparation.

[0046] The ultrafine molybdenum oxide nanosheets are prepared as follows: Using ammonium molybdate, oleylamine and oleic acid as raw materials, synthesizing ultrafine molybdenum oxide nanosheets in deionized water; wherein, the mass-volume ratio of the ammonium molybdate solution is 40 - 50 g / L, the volume ratio of the ammonium molybdate solution, oleylamine and oleic acid is 2:2:5, and the reaction conditions are 200 °C for 6 h.

[0047] After dissolving the ultrafine molybdenum oxide nanomaterials in ethanol, adding PTFE powder, stirring and drying to obtain a mixture, placing the mixture in a high-speed mixer to disperse it, and sieving it through a 100-mesh sieve, a uniform mixed powder is obtained. The mixed powder is molded by die pressing and sintering to obtain a PTFE composite filled with ultrafine molybdenum oxide nanomaterials.

[0048] The PTFE resin model is selected from CGM-16(F), M18, M18-F or M11.

[0049] The mass percentage of the ultrafine molybdenum oxide nanomaterial in the polytetrafluoroethylene composite material is 5wt% - 50wt%.

[0050] The pressure during the molding of the mixed powder is 30 - 40 MPa, and the pressure holding time is 4 - 5 min.

[0051] The process conditions during sintering are as follows: heating from room temperature to 330 °C at a heating rate of 120 - 200 °C / h, holding at 330 °C for 1 - 2 h; heating from 330 °C to 370 - 380 °C at a heating rate of 120 - 200 °C / h, holding at 370 - 380 °C for 1 - 2 h; cooling from 370 - 380 °C to 330 °C at a cooling rate of 120 - 200 °C / h, holding at 330 °C for 1 - 2 h; cooling from 330 °C to room temperature at a cooling rate of 30 - 120 °C / h.

[0052] The technical solution of the present invention is studied by the following examples, and the specific research methods and results are as follows:

[0053] Example 1

[0054] A preparation method of a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial, comprising the following steps:

[0055] S1. Dissolve 1.235 g of ammonium molybdate and 3.0 g of glycine in 200 mL of pure water respectively. The molar ratio of ammonium molybdate to glycine is 1:40. Add 4.5 mL of 12.0 mol / L hydrochloric acid solution to the ammonium molybdate solution. The molar ratio of ammonium molybdate to hydrochloric acid is 1:250. Then add the glycine solution, place it in an oven for hydrothermal reaction at 180 °C for 12 h, wash and dry to obtain the ultrafine molybdenum oxide nanomaterial.

[0056] S2. Dissolve 1 g of ultrafine molybdenum oxide nanomaterial in ethanol, then add 1.5 g of PTFE powder, stir and dry to obtain a mixture. Place the mixture in a high-speed mixer to disperse it, and sieve it through a 100-mesh sieve to obtain a uniform mixed powder. Mold the mixed powder with a molding pressure of 30 MPa and a pressure holding time of 4 min, and then sinter it into a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial.

[0057] Among them, the PTFE resin model is CGM-16(F), and the mass percentage of the ultrafine molybdenum oxide nanomaterial in the polytetrafluoroethylene composite material is 40%; the sintering process conditions are: rising from room temperature to 330 °C, with a heating rate of 120 °C / h, holding at 330 °C for 2 h; rising from 330 °C to 380 °C, with a heating rate of 200 °C / h, holding at 380 °C for 2 h; dropping from 380 °C to 330 °C, with a cooling rate of 200 °C / h, holding at 330 °C for 2 h; dropping from 330 °C to room temperature, with a cooling rate of 120 °C / h.

[0058] Example 2

[0059] A preparation method of a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials includes the following steps:

[0060] S1. Dissolve 2.5 g of ammonium molybdate and 0.25 g of thiomalic acid in 100 mL of pure water respectively. The mass ratio of ammonium molybdate to thiomalic acid is 1:0.1. Add 20 mL of 1 mol / L hydrochloric acid solution to the ammonium molybdate solution. The molar ratio of ammonium molybdate to hydrochloric acid is 1:10. Then add the thiomalic acid solution to finally obtain a blue solution. Spray drying is used to obtain ultrafine molybdenum oxide nanomaterials.

[0061] S2. Dissolve 2 g of ultrafine molybdenum oxide nanomaterials in ethanol, then add 3 g of PTFE powder. After stirring and drying, a mixture is obtained. The mixture is placed in a high-speed mixer to be dispersed and sieved through a 100-mesh sieve to obtain a uniform mixed powder. The mixed powder is molded under a molding pressure of 30 MPa and a pressure holding time of 4 min, and then sintered into a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials.

[0062] Among them, the PTFE resin model is CGM-16(F), and the mass percentage of the ultrafine molybdenum oxide nanomaterial in the polytetrafluoroethylene composite material is 40%; the sintering process conditions are: rising from room temperature to 330 °C, with a heating rate of 120 °C / h, holding at 330 °C for 2 h; rising from 330 °C to 380 °C, with a heating rate of 200 °C / h, holding at 380 °C for 2 h; dropping from 380 °C to 330 °C, with a cooling rate of 200 °C / h, holding at 330 °C for 2 h; dropping from 330 °C to room temperature, with a cooling rate of 120 °C / h.

[0063] Example 3

[0064] A preparation method of a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials includes the following steps:

[0065] S1. Dissolve 2.5 g of ammonium molybdate and 0.5 g of thiomalic acid in 100 mL of pure water respectively. The mass ratio of ammonium molybdate to thiomalic acid is 1:0.2. Add 16 mL of 1 mol / L hydrochloric acid solution to the ammonium molybdate solution. The molar ratio of ammonium molybdate to hydrochloric acid is 1:8. Then add the thiomalic acid solution. Finally, a blue solution is obtained. Spray drying is adopted to obtain ultrafine molybdenum oxide nanomaterials.

[0066] S2. Dissolve 5 g of ultrafine molybdenum oxide nanomaterials in ethanol, then add 5 g of PTFE powder. After stirring and drying, a mixture is obtained. The mixture is placed in a high-speed mixer to be dispersed and sieved through a 100-mesh sieve to obtain a uniform molybdenum mixed powder. The mixed powder is molded under a molding pressure of 40 MPa and a pressure holding time of 4.5 min, and then sintered into shape to obtain a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials.

[0067] Among them, the PTFE resin model is M18-F, and the mass percentage of the ultrafine molybdenum oxide nanomaterials in the polytetrafluoroethylene composite material is 50%; the process conditions of the sintering are as follows: rise from room temperature to 330 °C at a heating rate of 200 °C / h, hold at 330 °C for 1.5 h; rise from 330 °C to 370 °C at a heating rate of 150 °C / h, hold at 370 °C for 2 h; drop from 370 °C to 330 °C at a cooling rate of 200 °C / h, hold at 330 °C for 2 h; drop from 330 °C to room temperature at a cooling rate of 30 °C / h.

[0068] Example 4

[0069] A preparation method of a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials, comprising the following steps:

[0070] S1. Dissolve 1.235 g of ammonium molybdate and 2.25 g of glycine in 200 mL of pure water respectively. The molar ratio of ammonium molybdate to glycine is 1:30. Add 4.5 mL of 10.8 mol / L hydrochloric acid solution to the ammonium molybdate solution. The molar ratio of ammonium molybdate to hydrochloric acid is 1:225. Then add the glycine solution, and carry out hydrothermal reaction at 180 °C in an oven for 12 h. Wash and dry to obtain ultrafine molybdenum oxide nanomaterials.

[0071] S2. Dissolve 5 g of ultrafine molybdenum oxide nanomaterials in ethanol, then add 95 g of PTFE powder. After stirring and drying, a mixture is obtained. The mixture is placed in a high-speed mixer to be dispersed and sieved through a 100-mesh sieve to obtain a uniform molybdenum mixed powder. The mixed powder is molded under a molding pressure of 35 MPa and a pressure holding time of 5 min, and then sintered into shape to obtain a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials.

[0072] Among them, the PTFE resin model is M18-F, and the mass percentage of the ultrafine molybdenum oxide nanomaterial in the polytetrafluoroethylene composite material is 5%; the sintering process conditions are: rising from room temperature to 330 °C at a heating rate of 150 °C / h, holding at 330 °C for 1 h; rising from 330 °C to 375 °C at a heating rate of 120 °C / h, holding at 375 °C for 1 h; cooling from 375 °C to 330 °C at a cooling rate of 120 °C / h, holding at 330 °C for 1 h; cooling from 330 °C to room temperature at a cooling rate of 100 °C / h.

[0073] Example 5

[0074] A preparation method of a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials, comprising the following steps:

[0075] S1. Mix 2 mL of ammonium molybdate aqueous solution, 2 mL of oleylamine and 5 mL of oleic acid. The mass of ammonium molybdate in the ammonium molybdate aqueous solution is 0.1 g. Place it in an oven and carry out a hydrothermal reaction at 200 °C for 6 h, wash and dry to obtain ultrafine molybdenum oxide nanomaterials.

[0076] S2. Dissolve 0.5 g of ultrafine molybdenum oxide nanomaterials in ethanol, then add 1.5 g of PTFE powder, stir and dry to obtain a mixture. Place the mixture in a high-speed mixer to disperse it, and sieve it through a 100-mesh sieve to obtain a uniform mixed powder. Mould the mixed powder, with a moulding pressure of 30 MPa and a pressure holding time of 4 min, and then sinter it into a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials.

[0077] Among them, the PTFE resin model is CGM-16(F), and the mass percentage of the ultrafine molybdenum oxide nanomaterial in the polytetrafluoroethylene composite material is 20%; the sintering process conditions are: rising from room temperature to 330 °C at a heating rate of 120 °C / h, holding at 330 °C for 2 h; rising from 330 °C to 380 °C at a heating rate of 200 °C / h, holding at 380 °C for 2 h; cooling from 380 °C to 330 °C at a cooling rate of 200 °C / h, holding at 330 °C for 2 h; cooling from 330 °C to room temperature at a cooling rate of 120 °C / h.

[0078] Comparative Example 1

[0079] A preparation method of a polytetrafluoroethylene composite material filled with nickel-titanium particles, comprising the following steps:

[0080] Polytetrafluoroethylene-nickel titanium mixtures containing nickel-titanium particles with different mass fractions (0 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt% respectively) were dispersed in ethanol. The resulting suspension was thoroughly mixed in a high-speed mixer (IKA T18 basic ultra-high-speed disperser) at a speed of 9000 r / min for 10 min. Then the powder was dried, and cylindrical molds with diameters of 10 mm and 20 mm were used respectively to cold press for 10 min under pressures of 10 MPa, 20 MPa, 30 MPa, 40 MPa and 50 MPa. It is disclosed in the prior art Tribological and compressive creep properties of polytetrafluoroethylene / nickel-titanium shape memory alloy composites.

[0081] In Examples 1 to 5 of the present invention, polytetrafluoroethylene composites filled with ultrafine molybdenum oxide nanomaterials with high mechanical properties and tribological properties were prepared. Taking the polytetrafluoroethylene composites filled with ultrafine molybdenum oxide nanomaterials in Examples 1, 2 and 5 as examples for research, the specific research methods and results are as follows:

[0082] Figure 1 The TEM spectrum shows that the obtained ultrafine molybdenum oxide nanomaterials are molybdenum oxide nanowires, molybdenum oxide nanosheets or molybdenum oxide quantum dots. The width of the molybdenum oxide nanowires is about 10 nm, and the length is about several micrometers. The particle size of the molybdenum oxide nanosheets is 100 - 200 nm, and the particle size of the molybdenum oxide quantum dots is 1 - 5 nm.

[0083] Figure 2 The SEM data shows that the ultrafine molybdenum oxide quantum dots are evenly filled and distributed in the PTFE powder particles.

[0084] According to Figure 3 The SEM data shows that in the sintered polytetrafluoroethylene composite filled with ultrafine molybdenum oxide nanomaterials, the ultrafine molybdenum oxide quantum dots are evenly filled and distributed in the PTFE.

[0085] According to Figure 4 As shown by the XRD data, PTFE corresponds to PDF card No. 41 - 2217, and the ultrafine molybdenum oxide quantum dots correspond to PDF card No. 76 - 1003.

[0086] Figure 5 is the compressive mechanical property diagram of pure PTFE (pure PTFE) and the polytetrafluoroethylene composite filled with ultrafine molybdenum oxide nanomaterials (MoO 3 / PTFE), Figure 5The results show that, compared with pure PTFE, the compression modulus and compression strength of MoO 3 / PTFE are both improved, and the mechanical properties are better.

[0087] Figure 6 Figure for the reciprocating friction and wear performance of pure PTFE (pure PTFE) and polytetrafluoroethylene composite filled with ultrafine molybdenum oxide nanomaterials (MoO 3 / PTFE), Figure 6 The results show that, compared with pure PTFE, MoO 3 / PTFE is more wear-resistant under both low and high loads, and the tribological properties are better.

[0088] Wear rate = Wearrate(MoO 3 / PTFE) - Wearrate(PTFE) / Wearrate(PTFE).

[0089] Figure 7 Figure for the scanning electron microscope of wear debris obtained from the reciprocating friction and wear of pure PTFE (pure PTFE). The results show that there are a large number of cracks on the surface of the wear debris, indicating that PTFE is not resistant to shear.

[0090] Figure 8 Figure for the scanning electron microscope of wear debris obtained from the reciprocating friction and wear of polytetrafluoroethylene composite filled with ultrafine molybdenum oxide nanomaterials. Compared with the wear debris of pure polytetrafluoroethylene, the number of cracks on the surface of the wear debris of the polytetrafluoroethylene composite filled with ultrafine molybdenum oxide nanomaterials is less and the size is smaller, indicating that the polytetrafluoroethylene composite filled with ultrafine molybdenum oxide nanomaterials is more wear-resistant.

[0091] Figure 4 and Figure 5 and Figure 9 The comparison results show that, compared with the polytetrafluoroethylene composite filled with nickel-titanium particles in Comparative Example 1, the wear rate of the polytetrafluoroethylene composite filled with ultrafine molybdenum oxide nanomaterials of the present invention is reduced to 20 - 25%, and the wear rate of Comparative Example 1 is reduced to 30 - 35%. Compared with the polytetrafluoroethylene composite filled with nickel-titanium particles in Comparative Example 1, the compression modulus of the polytetrafluoroethylene composite filled with ultrafine molybdenum oxide nanomaterials of the present invention is increased by 5 - 6 times.

[0092] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations. The above-described embodiments are merely preferred embodiments given to fully illustrate the present invention, and the scope of protection is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the scope of protection of the present invention, and the scope of protection of the present invention is subject to the claims.

Claims

1. A method for preparing a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials, characterized in that: The steps include: The ultrafine molybdenum oxide nanomaterial is dispersed in a solvent, and then polytetrafluoroethylene is added, mixed, and dried to obtain a mixture, and the mixture is sequentially dispersed, sieved, molded, and then sintered to obtain a polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial; Wherein, the ultrafine molybdenum oxygen nanomaterial is selected from ultrafine molybdenum oxygen nanowires, ultrafine molybdenum oxygen nanoquantum dots or ultrafine molybdenum oxygen nanosheets.

2. The method for preparing the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial according to claim 1, characterized in that: In the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials, the mass percentage of the ultrafine molybdenum oxide nanomaterials is 5wt% to 50wt%.

3. The method for preparing the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial according to claim 1, characterized in that: The molding conditions are: maintaining the pressure at 30-40 MPa for 4-5 minutes.

4. The method for preparing the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial according to claim 1, characterized in that: The sintering conditions are as follows: heating from room temperature to 330°C, keeping at 330°C for 1 to 2 hours; heating from 330°C to 370-380°C, keeping at 370-380°C for 1 to 2 hours; cooling from 370-380°C to 330°C, keeping at 330°C for 1 to 2 hours and then cooling to room temperature.

5. The method for preparing the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial according to claim 1, characterized in that: Ultrafine molybdenum oxide nanowires are prepared according to the following steps: Adding glycine solution and acid solution into ammonium molybdate solution, and obtaining ultrafine molybdenum-oxygen nanowires through hydrothermal reaction; The molar ratio of ammonium molybdate to glycine is 1:30-40, and the molar ratio of ammonium molybdate to the acid in the acid solution is 1:225-250.

6. The method for preparing the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial according to claim 1, characterized in that: Ultrafine molybdenum oxide nano-quantum dots were prepared according to the following steps: Adding thiomalic acid solution and acid solution to ammonium molybdate solution, mixing evenly and then spray drying to obtain ultrafine molybdenum oxygen nano-quantum dots; The mass ratio of ammonium molybdate to thiomalic acid is 1:0.1-0.2, and the molar ratio of ammonium molybdate to the acid in the acid solution is 1:8-10.

7. The method for preparing the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterial according to claim 1, characterized in that: Ultrafine molybdenum oxide nanosheets are prepared according to the following steps: Adding oleylamine and oleic acid into ammonium molybdate solution, and undergoing hydrothermal reaction, ultrafine molybdenum oxide nanosheets are obtained; The mass volume ratio of the ammonium molybdate solution is 40-50 g / L, and the volume ratio of the ammonium molybdate solution, oleylamine and oleic acid is 2:2:

5.

8. A polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials prepared by the preparation method according to any one of claims 1 to 7.

9. The polytetrafluoroethylene composite material filled with ultrafine molybdenum oxide nanomaterials according to claim 8, characterized in that: In the polytetrafluoroethylene composite material filled with ultrafine molybdenum oxygen nanomaterials, the width of the ultrafine molybdenum oxygen nanowires is 10 to 20 nm, the particle size of the ultrafine molybdenum oxygen nanoquantum dots is 1 to 5 nm, and the particle size of the ultrafine molybdenum oxygen nanosheets is 100 to 200 nm.

10. Use of the polytetrafluoroethylene composite material filled with the ultrafine molybdenum oxide nanomaterial according to claim 8 in the preparation of special engineering plastics.

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