Gradient doping modification method of ultra-high molecular weight polyethylene for snowboard
By using gradient doping technology in skis with nanofillers of carbon nitride polymer, graphene oxide and hexagonal boron nitride, the problems of poor friction performance and low layer structure connection force of ultra-high molecular weight polyethylene skis are solved, and the problem of poor friction performance and low layer structure connection force is achieved. Better drag reduction performance and environmentally friendly production.
Patent Information
- Application Number
- CN202411235071.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-04
- Publication Date
- 2024-12-10
AI Technical Summary
The friction coefficient of ultra-high molecular weight polyethylene skis increases during use, resulting in sliding obstacles. The products of the prior art have poor dimensional accuracy and low layer structure connection force, which easily disintegrates, increasing maintenance difficulty and environmental pollution.
Using gradient doping method, carbon nitride polymer, graphene oxide and hexagonal boron nitride are used as nanofillers to enhance the friction performance and interlayer connection strength of ultra-high molecular weight polyethylene, and a three-layer structure is formed through hot pressing forming technology. Snowboard board.
It significantly reduces the friction coefficient, improves wear resistance and board strength, enhances the drag reduction and mechanical properties of the skis, and reduces the amount of snow wax, and improves the environmental protection of production.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of polymer material preparation, and in particular relates to a gradient doping modification method of ultra-high molecular weight polyethylene for ski boards. Background Art
[0002] Ultra-high molecular weight polyethylene is polyethylene with a molecular weight of more than 1 million. It is a linear thermoplastic engineering plastic with excellent comprehensive properties. The extremely high molecular weight leads to strong entanglement between molecules, which brings excellent mechanical properties, making it have good lubrication, impact resistance, chemical corrosion resistance and other properties. However, compared with other engineering plastics, its resistance to friction and wear is poor, which affects its use effect and application range.
[0003] Snowboards are a type of sports equipment that facilitates people to move forward on the snow and is used to increase skiing speed. The bottom of the snowboard is generally made of ultra-high molecular weight polyethylene. Although this polymer material has strong wear resistance, self-lubrication, relatively high strength, stable chemical properties, and strong anti-aging properties, it is easy to be damaged after sliding on the snow for a long time, and the friction coefficient becomes larger, which hinders sliding on the snow. Therefore, it needs to be waxed and maintained frequently during use. However, there are a series of problems such as waxing is inconvenient and the fluorine element in the snow wax will pollute the environment. At the same time, it also increases the difficulty of large-scale production of corresponding snowboards.
[0004] The Chinese invention patent with application number 202010449541.8 discloses a process for preparing ultra-high molecular weight polyethylene for skis, including the preparation of the upper and lower structures of the skis, and has the following steps: adding hexane solvent, catalyst, and activator into the reaction space, and pressurizing and heating the inside of the closed reaction space; gradually introducing ethylene into the closed reaction space to ensure that the temperature and pressure in the reaction space are constant to generate ultra-high molecular weight polyethylene material; heating a portion of the ultra-high molecular weight polyethylene finished material to a molten state and then compounding it with carbon nanotubes to generate an ultra-high molecular weight polyethylene composite material; extruding it into a mold structure to make a lower structure; continuing to heat the remaining part of the ultra-high molecular weight polyethylene finished material to a molten state, extruding it into the mold structure to make an upper structure and combining it with the lower structure into a whole.
[0005] The Chinese invention patent with application number 201410262850.9 discloses a method for preparing a low-temperature resistant special fiber reinforced ski board, wherein the inner core is made of polybutylene terephthalate (PBT) as the main body, functionalized polyolefin elastomer as the toughening agent, and carbon fiber as the reinforcing material, with a thickness of 5 to 7 mm, the bottom plate is a functionalized linear low-density polyethylene (LLDPE) material with a thickness of 1 to 2 mm, and the surface layer is made of a glass fiber reinforced PBT composite material with a thickness of 2 to 3 mm. The inner core layer made of a functionalized polyolefin elastomer toughened PBT resin blend has quite good toughness, high impact strength at the use temperature of the ski board, and considerable strength after being compounded with carbon fiber, and each layer is well combined together through the heating molding process.
[0006] It can be seen that for products such as skis, the main component is polyethylene or other polyesters, and the performance is adjusted by additives. The processing method is all in the form of heated molding. Heated molding generally puts powder, granular, pelletized, sheet, or even preforms made into a shape similar to the product in the cavity of a heated mold, and then closes the mold and presses it to form and solidify or vulcanize it, and then demolds it to obtain the product. This method is particularly suitable for the molding of thermosetting plastics. For thermoplastic ultra-high molecular weight polyethylene materials, the disadvantage is that the product size accuracy is poor, the connection force of the product's various layers is low, and it is easy to disintegrate during use. Summary of the invention
[0007] The purpose of the present invention is to provide a gradient doping modification method for ultra-high molecular weight polyethylene for skis, which overcomes the shortcomings of the prior art. Based on an ultra-high molecular weight polyethylene substrate, carbon nitride polymer, graphene oxide, and hexagonal boron nitride are used as nanofillers, and gradient doping technology is adopted to enhance the connection strength between layers. The ultra-high molecular weight polyethylene is modified to reduce its friction coefficient and increase its wear resistance, thereby obtaining better drag reduction performance and board strength.
[0008] To achieve the above object, the present invention is implemented through the following technical solutions:
[0009] A gradient doping modification method for ultra-high molecular weight polyethylene for skis, characterized in that the gradient doping method is adopted, the upper layer is ultra-high molecular weight polyethylene powder, the middle layer is ultra-high molecular weight polyethylene powder added with carbon nitride polymer, and the lower layer is ultra-high molecular weight polyethylene powder added with hybrid filler, and the specific operation steps are as follows: 1) Preparation of carbon nitride polymer, take urea and put it into an oven, dry it at a temperature of 80-85°C for 10-12 hours, put the dried urea in a crucible, and transfer it to a muffle furnace, Heat to 500-550°C, keep warm for 4-6 hours, cool naturally to room temperature, and obtain a pale yellow graphite phase carbon nitride polymer, which is ground for later use; 2) Preparation of hybrid filler, take 0.2-0.3g carbon nitride polymer, 0.1-0.2g graphene oxide and 0.1-0.2g hexagonal boron nitride as precursors, add 15-25mL deionized water and stir evenly, transfer the obtained mixed solution to a hydrothermal kettle, and hydrothermally react at 180-200°C for 12-24h; the obtained product is filtered, washed and , drying to obtain a hybrid filler of carbon nitride polymer + graphene oxide + hexagonal boron nitride; 3) preparing ingredients, preparing modified bottom layer material A, weighing 2-20% of the weight percentage of the hybrid filler prepared in step 2), and the balance being ultra-high molecular weight polyethylene powder, using a ball mill to mix and stir evenly; preparing middle layer material B, weighing 4-40% g of carbon nitride polymer, and the balance being ultra-high molecular weight polyethylene powder, using a ball mill to mix and stir evenly; preparing upper layer material C, all of which are ultra-high molecular weight polyethylene powder. Molecular weight polyethylene powder; 4) gradient doping, filling the powder material into the mold in layers in the order of top, middle and bottom, and hot pressing molding, the hot pressing process is divided into three steps: ① room temperature ~ 160 ℃ stage, the heating rate is 5 ~ 10 ℃ / min; ②>160~180 ℃ stage, pressurize and degas the mold with a pressure of 20~25MPa; ③>180 ℃ stage, at a temperature of 180~230 ℃, maintain a pressure of 10~12MPa, keep warm for 20~30min, and obtain the board material for ski board.
[0010] In the step 3), the weight ratio of the three layers of materials is A:B:C=1:1-2:1-2.
[0011] The ultra-high molecular weight polyethylene has a molecular weight of 4 to 5 million, an average powder particle size of 15 to 20 μm, and a melting point of 140 to 150° C. It is produced by Dongguan Jinheng Plastic Co., Ltd.
[0012] The urea was of analytical grade and produced by Shanghai Aladdin Biochemical Technology Co., Ltd.
[0013] The graphene oxide is a single-layer graphene oxide with a sheet diameter of 1-10 μm, produced by Shenzhen Suiheng Technology Co., Ltd.
[0014] The physical and chemical parameters of the hexagonal boron nitride are: average particle size 10 μm, purity 99%, and density 2.27 g / cm3.
[0015] The qualified physical and chemical indicators of the hybrid filler are: average particle size 10-15 μm, average density 1.25-1.55 g / cm3.
[0016] The bending strength of the snowboard plate is 33-35 MPa, the impact strength is 139-142 MPa, and the hardness is 43-45 MPa.
[0017] The elastic modulus of the snowboard plate is 610-612 MPa.
[0018] The working principle of each component of the present invention is described as follows:
[0019] The role of carbon nitride polymer is to give ultra-high molecular weight polyethylene surface active sites and rough microstructure to enhance the interfacial interaction of the composite material, which is beneficial to the transfer of stress from ultra-high molecular weight polyethylene to the interface of the composite material during sliding. At the same time, the carbon nitride polymer nanosheet structure can give the composite material excellent self-lubricating properties by promoting the formation of transfer film.
[0020] The role of graphene oxide is: the modified graphene-based material adheres to the friction contact surface during the friction process and fills the damaged area to ensure rapid and stable dispersion of the material, thereby reducing wear.
[0021] The role of hexagonal boron nitride is to improve the interfacial compatibility, thereby enhancing the processability of modified ultra-high molecular weight polyethylene, and to improve the mechanical properties of the composite material by forming hydrogen bonds.
[0022] The role of the hybrid filler is: through the synergistic effect of carbon nitride polymer, graphene oxide and hexagonal boron nitride, the modified ultra-high molecular weight polyethylene material is given better mechanical properties, the stable dispersion of the filler is promoted, and the transfer film is formed by enhancing the interface effect, thereby enhancing the tribological properties of the ultra-high molecular weight polyethylene.
[0023] Compared with the prior art, the present invention has the following beneficial effects:
[0024] 1) On the ultra-high molecular weight polyethylene ski board substrate, carbon nitride polymer, graphene oxide and hexagonal boron nitride are used as nanofillers, and the ultra-high molecular weight polyethylene is modified by gradient doping technology, which enhances the connection strength between the layers, reduces the friction coefficient and increases the wear resistance, thereby obtaining better drag reduction performance and board strength. Compared with the existing materials for making snowboards, the ultra-high molecular weight polyethylene modified with carbon nitride has a lower friction coefficient and significantly improved wear resistance.
[0025] 2) Carbon nitride polymer is obtained by direct calcination of urea, which is low-cost and contains only two elements, carbon and nitrogen, in its structure. It is green and environmentally friendly. Graphene oxide and hexagonal boron nitride are layered anti-friction agents with excellent anti-friction effect, which can reduce the amount of snow wax used and is more green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 The SEM photos of the microscopic comparison of the friction surface between the gradient doped modified plate (b) and the pure ultra-high molecular weight polyethylene substrate (a) in Example 1 of the present invention;
[0027] Figure 2 is the XRD spectrum of the graphite phase carbon nitride sample prepared in step 2) of the present invention;
[0028] Figure 3 is a SEM image of an ultra-high molecular weight polyethylene sample prepared under the conditions of hot pressing molding in step 4) of the present invention;
[0029] Figure 4 2 is a strength comparison diagram of the embodiments of the present invention. DETAILED DESCRIPTION
[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.
[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the specific embodiments required to be used in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some implementation methods of the present invention. For ordinary technicians in this field, other specific embodiments can be obtained based on these specific embodiments without paying creative work.
[0032] The components of the embodiments of the present invention generally described and shown in the specific embodiments herein can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the specific embodiments is not intended to limit the scope of the invention claimed, but merely represents selected embodiments of the present invention.
[0033] The components used in the following examples are described as follows: The molecular weight of ultra-high molecular weight polyethylene is 4-5 million, the average particle size of the powder is 15-20 μm, the melting point is 140-150°C, and it is produced by Dongguan Jinheng Plastic Co., Ltd. Urea is analytically pure and is produced by Shanghai Aladdin Biochemical Technology Co., Ltd. Graphene oxide is a single-layer graphene oxide with a sheet diameter of 1-10 μm, produced by Shenzhen Suiheng Technology Co., Ltd. The physicochemical parameters of hexagonal boron nitride are: average particle size 10 μm, purity 99%, and density 2.27 g / cm3. The qualified physicochemical indicators of the hybrid filler are: average particle size 10-15 μm, average density 1.25-1.55 g / cm3.
[0034] Example 1
[0035] The invention discloses a gradient doping modification method for ultra-high molecular weight polyethylene for skis, which adopts a gradient doping method, wherein the upper layer is ultra-high molecular weight polyethylene powder, the middle layer is ultra-high molecular weight polyethylene powder added with carbon nitride polymer, and the lower layer is ultra-high molecular weight polyethylene powder added with hybrid filler. The specific operation steps are as follows:
[0036] 1) Preparation of carbon nitride polymer: put urea into an oven, dry it at 80-85°C for 10-12 hours, put the dried urea into a crucible, transfer it to a muffle furnace, heat it to 500-550°C, keep it warm for 4-6 hours, and naturally cool it to room temperature to obtain a pale yellow graphite phase carbon nitride polymer, which is ground for later use; the XRD spectrum of the carbon nitride polymer has two characteristic peaks, which are located at 2θ=13° and 27.5°, respectively corresponding to the two-dimensional planar structure and interlayer structure of graphite phase carbon nitride, see Figure 2 .
[0037] 2) Preparation of hybrid filler: 0.25 g carbon nitride polymer, 0.125 g graphene oxide and 0.125 g hexagonal boron nitride were taken as precursors, added into 20 mL deionized water and stirred evenly, and the obtained mixed solution was transferred into a hydrothermal kettle, and hydrothermally reacted at 180° C. for 12 h; the obtained product was filtered, washed and dried to obtain a qualified hybrid filler of carbon nitride polymer + graphene oxide + hexagonal boron nitride;
[0038] 3) Ingredients: prepare modified bottom layer material A, weigh 0.5g of the hybrid filler prepared in step 2), and the balance is 4.5g of ultra-high molecular weight polyethylene powder, and mix and stir evenly using a ball mill; prepare middle layer material B, weigh 0.25g of carbon nitride polymer in terms of weight percentage, and the balance is 4.75g of ultra-high molecular weight polyethylene powder, and mix and stir evenly using a ball mill; prepare 5g of upper layer material C, which is all ultra-high molecular weight polyethylene powder; the weight ratio of the three layers of materials A:B:C is 1:1:1.
[0039] 4) Gradient doping, filling the powder materials into the mold in layers in the order of top, middle and bottom, and hot pressing and sintering are carried out. The hot pressing process is divided into three steps: ① room temperature ~ 160 ℃ heating stage, the heating rate is 10 ℃ / min; ② ≥ 160 ~ 180 ℃ heating stage, pressurizing and degassing the mold with a pressure of 20MPa; ③>180 ℃ stage, at a temperature of 180 ℃, maintaining a pressure of 10MPa, keeping warm for 20min, and obtaining the board for skis.
[0040] Example 2
[0041] The invention discloses a gradient doping modification method for ultra-high molecular weight polyethylene for skis, which adopts a gradient doping method, wherein the upper layer is ultra-high molecular weight polyethylene powder, the middle layer is ultra-high molecular weight polyethylene powder added with carbon nitride polymer, and the lower layer is ultra-high molecular weight polyethylene powder added with hybrid filler. The specific operation steps are as follows:
[0042] 1) Preparation of carbon nitride polymer, same as in Example 1;
[0043] 2) Preparation of hybrid filler: 0.20 g carbon nitride polymer, 0.15 g graphene oxide and 0.15 g hexagonal boron nitride were taken as precursors, added into 20 mL deionized water and stirred evenly, and the obtained mixed solution was transferred into a hydrothermal kettle, and hydrothermally reacted at 200° C. for 12 h; the obtained product was filtered, washed and dried to obtain a qualified hybrid filler of carbon nitride polymer + graphene oxide + hexagonal boron nitride;
[0044] 3) Ingredients: weigh 4.0 g of ultra-high molecular weight polyethylene powder, add 1.0 g of the hybrid filler prepared in step 2), use a ball mill to mix and stir for 6 hours, and collect as a modified bottom layer material A; weigh 9.6 g of ultra-high molecular weight polyethylene powder, add 0.4 g of carbon nitride polymer, use a ball mill to mix and stir for 6 hours, and collect as a middle layer material B; weigh 10 g of ultra-high molecular weight polyethylene powder as an upper layer material C; the weight ratio of the three layers A:B:C is 1:2:2.
[0045] 4) Gradient doping, filling the powder material into the mold in layers in the order of top, middle and bottom, and hot pressing and sintering are carried out. The hot pressing process is divided into three steps: ① Initial heating stage: room temperature ~ 160℃, heating rate is 5℃ / min; ② 160~180℃ stage, pressurize and degas the mold with a pressure of 25MPa; ③ 180℃ stage, at a temperature of 200℃, maintain a pressure of 12MPa, keep warm for 30min, and obtain the board for skis.
[0046] Example 3
[0047] The invention discloses a gradient doping modification method for ultra-high molecular weight polyethylene for skis, which adopts a gradient doping method, wherein the upper layer is ultra-high molecular weight polyethylene powder, the middle layer is ultra-high molecular weight polyethylene powder added with carbon nitride polymer, and the lower layer is ultra-high molecular weight polyethylene powder added with hybrid filler. The specific operation steps are as follows:
[0048] 1) Preparation of carbon nitride polymer, same as in Example 1;
[0049] 2) Preparation of hybrid filler: 0.30 g carbon nitride polymer, 0.10 g graphene oxide and 0.10 g hexagonal boron nitride were taken as precursors, added into 20 mL deionized water and stirred evenly, and the obtained mixed solution was transferred into a hydrothermal kettle and subjected to hydrothermal reaction at 190° C. for 24 h; the obtained product was filtered, washed and dried to obtain a qualified hybrid filler of carbon nitride polymer + graphene oxide + hexagonal boron nitride;
[0050] 3) Ingredients: prepare modified bottom layer material A, weigh 0.25g of the hybrid filler prepared in step 2), and the balance is 4.75g of ultra-high molecular weight polyethylene powder, and mix and stir evenly using a ball mill; prepare middle layer material B, weigh 2.5g of carbon nitride polymer in terms of weight percentage, and the balance is 7.5g of ultra-high molecular weight polyethylene powder, and mix and stir evenly using a ball mill; prepare 5g of upper layer material C, which is all ultra-high molecular weight polyethylene powder; the weight ratio of the three layers of material A:B:C is 1:2:1.
[0051] 4) Gradient doping, filling the powder material into the mold in layers in the order of top, middle and bottom, and hot pressing is carried out. The hot pressing process is divided into three steps: ① room temperature ~ 160 ℃ heating stage, the heating rate is 8 ℃ / min; ②>160~180 ℃ heating stage, pressurizing and degassing the mold with a pressure of 22MPa; ③>180 ℃ stage, at a temperature of 210 ℃, maintaining a pressure of 12MPa, keeping warm for 30min, and obtaining the board for skis.
[0052] Example 4
[0053] The invention discloses a gradient doping modification method for ultra-high molecular weight polyethylene for skis, which adopts a gradient doping method, wherein the upper layer is ultra-high molecular weight polyethylene powder, the middle layer is ultra-high molecular weight polyethylene powder added with carbon nitride polymer, and the lower layer is ultra-high molecular weight polyethylene powder added with hybrid filler. The specific operation steps are as follows:
[0054] 1) Preparation of carbon nitride polymer, same as in Example 1;
[0055] 2) Preparation of hybrid filler: 0.25 g carbon nitride polymer, 0.175 g graphene oxide and 0.175 g hexagonal boron nitride were taken as precursors, added into 25 mL deionized water and stirred evenly, and the obtained mixed solution was transferred into a hydrothermal kettle and subjected to hydrothermal reaction at 200° C. for 20 h; the obtained product was filtered, washed and dried to obtain a hybrid filler of carbon nitride polymer + graphene oxide + hexagonal boron nitride;
[0056] 3) Ingredients: prepare modified bottom layer material A, weigh 0.75g of the hybrid filler prepared in step 2), and the balance is 4.25g of ultra-high molecular weight polyethylene powder, and mix and stir evenly using a ball mill; prepare middle layer material B, weigh 1.0g of carbon nitride polymer in terms of weight percentage, and the balance is 4.0g of ultra-high molecular weight polyethylene powder, and mix and stir evenly using a ball mill; prepare 10g of upper layer material C, which is all ultra-high molecular weight polyethylene powder; the weight ratio of the three layers of materials A:B:C is 1:1:2.
[0057] 4) Gradient doping, filling the powder material into the mold in layers in the order of top, middle and bottom, and hot pressing is carried out. The hot pressing process is divided into three steps: ① room temperature ~ 160 ℃ heating stage, the heating rate is 7.5 ℃ / min; ②>160~180 ℃ heating stage, pressurizing and degassing the mold with a pressure of 20MPa; ③>180 ℃ stage, at a temperature of 230 ℃, maintaining a pressure of 10MPa, keeping warm for 25min, and obtaining the board for skis.
[0058] Comparative Example 1 (pure ultra-high molecular weight polyethylene)
[0059] Weigh 15g of ultra-high molecular weight polyethylene powder and carry out hot pressing sintering. The hot pressing process is divided into three steps: ① initial heating stage: room temperature ~ 160℃, heating rate is 10℃ / min; ② 160~180℃ stage, pressurize and degas the mold with 5MPa pressure; ③ 180℃ stage, at a temperature of ≥180℃, maintain a pressure of 10MPa, keep warm for 20min, and obtain the ski board.
[0060] Comparative Example 2 (without addition of carbon nitride polymer)
[0061] 1) Preparation of hybrid filler: 0.25 g of graphene oxide and 0.25 g of hexagonal boron nitride were taken as precursors, added into 20 mL of deionized water and stirred evenly, and the obtained mixed solution was transferred into a hydrothermal reactor and subjected to hydrothermal reaction at 180° C. for 12 h; the obtained product was filtered, washed and dried to obtain a hybrid filler of graphene oxide + hexagonal boron nitride;
[0062] 2) Ingredients: weigh 14.5 g of ultra-high molecular weight polyethylene powder, add 0.25 g of the hybrid filler prepared in step 1), use a ball mill to mix and stir for 6 hours, and perform hot pressing sintering. The hot pressing process is divided into three steps: ① At room temperature ~ 160°C, the heating rate is 10°C / min; ② At a temperature of 160-180°C, pressurize and degas the mold with a pressure of 5MPa; ③ At a temperature of 180°C, maintain a pressure of 10MPa and keep warm for 20 minutes to obtain a plate for a ski board.
[0063] Comparative Example 3 (two-layer structure)
[0064] 1) Preparation of hybrid filler: 0.25 g of graphene oxide and 0.25 g of hexagonal boron nitride were taken as precursors, added into 20 mL of deionized water and stirred evenly, and the obtained mixed solution was transferred into a hydrothermal reactor and subjected to hydrothermal reaction at 180° C. for 12 h; the obtained product was filtered, washed and dried to obtain a hybrid filler of graphene oxide + hexagonal boron nitride;
[0065] 2) Ingredients: Prepare modified bottom layer material A, weigh 0.5 g of the hybrid filler prepared in step 1), and the remainder is 4.5 g of ultra-high molecular weight polyethylene powder, and mix and stir evenly using a ball mill; prepare 5 g of upper layer material B, which is entirely ultra-high molecular weight polyethylene powder; the weight ratio of the two layers of material A:B is 1:1.
[0066] 3) Gradient doping, filling the powder material into the mold in layers in an upward and downward order, and hot pressing and sintering are carried out. The hot pressing process is divided into three steps: ① room temperature to 160℃ heating stage, the heating rate is 10℃ / min; ② ≥160~180℃ heating stage, pressurizing and degassing the mold with a pressure of 20MPa; ③>180℃ stage, at a temperature of 180℃, maintaining a pressure of 10MPa, and keeping warm for 20min to obtain the ski board.
[0067] The performance parameters of the embodiments of the present invention and the comparative examples are shown in Table 1.
[0068] Table 1
[0069]
[0070] The friction and wear performance test in the above embodiments and comparative examples of the present invention is to use MFT-4000 multifunctional material surface performance tester, with a silicon nitride ball of 2 mm in diameter as the friction pair, at room temperature (25°C), a sliding speed of 70 mm / min, a test time of 1 hour, and an applied load of 80 MPa to study the friction and wear performance of ultra-high molecular weight polyethylene modified by the gradient doping method under different application load conditions. The friction coefficient is automatically output after the collected data is processed by the connected computer.
[0071] The specific wear rate is calculated with reference to the specific wear rate of the fabric lining material, using the formula K=AV / P·L, where: K is the specific wear rate; AV is the wear volume; P is the applied load; and L is the sliding distance.
[0072] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A gradient doping modification method for ultra-high molecular weight polyethylene for skis, It is characterized in that The gradient doping method is adopted, the upper layer is ultra-high molecular weight polyethylene powder, the middle layer is ultra-high molecular weight polyethylene powder added with carbon nitride polymer, and the lower layer is ultra-high molecular weight polyethylene powder added with hybrid filler. The specific operation steps are as follows: 1) Preparation of carbon nitride polymer: put urea into an oven, dry it at 80-85°C for 10-12 hours, put the dried urea into a crucible, transfer it to a muffle furnace, heat it to 500-550°C, keep it warm for 4-6 hours, and naturally cool it to room temperature to obtain a light yellow graphite phase carbon nitride polymer, which is ground for later use; 2) Preparation of hybrid filler: 0.2-0.3 g carbon nitride polymer, 0.1-0.2 g graphene oxide and 0.1-0.2 g hexagonal boron nitride are taken as precursors, added into 15-25 mL deionized water and stirred evenly, and the obtained mixed solution is transferred into a hydrothermal kettle, and hydrothermally reacted at 180-200° C. for 12-24 h; the obtained product is filtered, washed and dried to obtain a hybrid filler of carbon nitride polymer + graphene oxide + hexagonal boron nitride; 3) Mixing ingredients: preparing modified bottom layer material A, weighing 2-20% by weight of the hybrid filler prepared in step 2), and the balance being ultra-high molecular weight polyethylene powder, and mixing and stirring them evenly using a ball mill; preparing middle layer material B, weighing 4-40% by weight of carbon nitride polymer, and the balance being ultra-high molecular weight polyethylene powder, and mixing and stirring them evenly using a ball mill; preparing upper layer material C, which is entirely ultra-high molecular weight polyethylene powder; 4) Gradient doping, filling the powder material into the mold in layers in the order of top, middle and bottom, and hot pressing is carried out. The hot pressing process is divided into three steps: ① room temperature to 160℃ heating stage, the heating rate is 5-10℃ / min; ②>160~180℃ heating stage, pressurizing and degassing the mold with a pressure of 20-25MPa; ③>180℃ stage, at a temperature of 180~230℃, maintaining a pressure of 10~12MPa, and keeping warm for 20~30min to obtain the plate for ski board.
2. A gradient doping modification method for ultra-high molecular weight polyethylene for skis according to claim 1, Features: In the step 3), the weight ratio of the three layers of materials is A:B:C=1:1-2:1-2.
3. The gradient doping modification method of ultra-high molecular weight polyethylene for skis according to claim 1, Features: The molecular weight of the ultra-high molecular weight polyethylene is 4 to 5 million, the average particle size of the powder is 15 to 20 μm, and the melting point is 140 to 150° C.
4. The gradient doping modification method of ultra-high molecular weight polyethylene for skis according to claim 1, Features: The urea was analytically pure.
5. The gradient doping modification method of ultra-high molecular weight polyethylene for skis according to claim 1, Features: The graphene oxide is a single-layer graphene oxide with a sheet diameter of 1-10 μm.
6. The gradient doping modification method of ultra-high molecular weight polyethylene for skis according to claim 1, Features: The average particle size of the hexagonal boron nitride is 10-15 μm, the purity is ≥99%, and the density is 2.27-2.45 g / cm 3 .
7. The gradient doping modification method of ultra-high molecular weight polyethylene for snowboards according to claim 1, Features: The qualified physical and chemical indicators of the hybrid filler are: average particle size 10-15 μm, average density 1.25-1.55 g / cm 3 .
8. The gradient doping modification method of ultra-high molecular weight polyethylene for snowboards according to claim 1, Features: The bending strength of the snowboard plate is 33-35 MPa, the impact strength is 139-142 MPa, and the hardness is 43-45 MPa.
9. The gradient doping modification method of ultra-high molecular weight polyethylene for snowboards according to claim 1, Features: The elastic modulus of the snowboard plate is 610-612 MPa.