Ultrahigh molecular weight polyethylene composite material and preparation method thereof

Abstract

The invention provides an ultra-high molecular weight polyethylene composite material and a preparation method thereof, and the ultra-high molecular weight polyethylene composite material comprises the following components in percentage by mass: 20%-30% of ultra-high molecular weight polyethylene, 70%-80% of high density polyethylene, 0.4%-0.7% of a graphene sheet layer and 0.15%-0.2% of an antioxidant, the ultra-high molecular weight polyethylene composite material has excellent melt fluidity and wear resistance, and can be processed and produced in batches.

Description

Technical Field

[0001] The invention belongs to the technical field of wear-resistant materials, and in particular relates to an ultra-high molecular weight polyethylene composite material and a preparation method thereof. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) is a linear polyethylene with a molecular weight greater than 1.5 million. UHMWPE has excellent wear resistance and is often used as a wear-resistant material. It has great advantages and important roles in high-performance fibers, lightweight composite materials, aerospace, defense equipment, etc. However, UHMWPE has a long molecular chain structure, and long molecular chains are prone to entanglement, resulting in poor fluidity of UHMWPE in the molten state, which limits the batch processing and wide application of UHMWPE.

[0003] Therefore, how to provide an ultra-high molecular weight polyethylene composite material with good melt fluidity and wear resistance is a technical problem to be solved urgently in this field. Summary of the invention

[0004] The invention provides an ultra-high molecular weight polyethylene composite material. The ultra-high molecular weight polyethylene composite material has excellent melt fluidity and wear resistance and can be processed and produced in batches.

[0005] The present invention also provides a method for preparing an ultra-high molecular weight polyethylene composite material. The ultra-high molecular weight polyethylene composite material prepared by the preparation method has excellent melt fluidity and wear resistance. At the same time, the preparation method has a simple process and is convenient for industrial production.

[0006] In a first aspect, the present invention provides an ultra-high molecular weight polyethylene composite material, comprising the following components, by mass percentage: 20%-30% ultra-high molecular weight polyethylene, 70%-80% high-density polyethylene, 0.4%-0.7% graphene sheet, and 0.15%-0.2% antioxidant.

[0007] The ultra-high molecular weight polyethylene composite material as described above, wherein the particle size of the graphene sheet layer is 7.00 μm-12.00 μm, and the thickness is less than 1 nm.

[0008] The ultra-high molecular weight polyethylene composite material as described above, wherein the molecular weight of the ultra-high molecular weight polyethylene is 3 million to 6 million;

[0009] The molecular weight of the high-density polyethylene is 500,000-1,000,000.

[0010] In the ultra-high molecular weight polyethylene composite material as described above, the antioxidant comprises a hindered phenol antioxidant.

[0011] The ultra-high molecular weight polyethylene composite material as described above, wherein the melt index of the ultra-high molecular weight polyethylene composite material is 6.7 g / 10 min-8.5 g / 10 min.

[0012] In a second aspect, the present invention provides a method for preparing the above-mentioned ultra-high molecular weight polyethylene composite material, comprising the following steps:

[0013] Ultra-high molecular weight polyethylene, high-density polyethylene, graphene sheets and antioxidants are melt-blended to obtain a blended material, which is then hot-pressed to obtain the ultra-high molecular weight polyethylene composite material.

[0014] The preparation method as described above, wherein the temperature of the melt blending is 180-200°C; and / or,

[0015] The melt blending time is 5 min-15 min.

[0016] The preparation method as described above, wherein the temperature of the hot pressing molding is 180-200°C.

[0017] The preparation method as described above, wherein the hot pressing forming comprises step-by-step hot pressing forming;

[0018] The conditions for the step-by-step hot pressing molding are: first pressurize to 2MPa-5MPa, release the pressure and exhaust after 1min-2min, then pressurize to 5MPa-7MPa, release the pressure and exhaust after 1min-2min, continue to pressurize to 8MPa-10MPa, release the pressure and exhaust after 1min-2min, and then pressurize to 12MPa-13MPa, release the pressure and exhaust after 7min-10min.

[0019] The preparation method as described above, wherein the preparation method further comprises the following steps: after the hot pressing forming, cold pressing the obtained hot pressing forming product to obtain the composite wear-resistant material;

[0020] The cold press forming conditions are: pressurizing to 12MPa-13MPa at 10-30°C and maintaining for 12min-16min.

[0021] The ultra-high molecular weight polyethylene composite material of the invention comprises ultra-high molecular weight polyethylene, high-density polyethylene, graphene sheets and antioxidants with specific contents. The ultra-high molecular weight polyethylene composite material has excellent melt fluidity and wear resistance and can be processed and produced in batches. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a dynamic mechanical analysis curve diagram of the ultra-high molecular weight polyethylene composite material in Example 1, the UHMWPE material in Comparative Example 1, and the UHMWPE-HDPE material in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In a first aspect, the present invention provides an ultra-high molecular weight polyethylene composite material, comprising the following components, by mass percentage: 20%-30% ultra-high molecular weight polyethylene, 70%-80% high-density polyethylene, 0.4%-0.7% graphene sheet, and 0.15%-0.2% antioxidant.

[0025] The ultra-high molecular weight polyethylene composite material of the present invention comprises specific contents of UHMWPE, HDPE, graphene sheets and antioxidants, and has excellent melt fluidity and wear resistance. Among them, compared with UHMWPE, HDPE has a lower molecular weight and melt viscosity, which can improve the melt fluidity of the ultra-high molecular weight polyethylene composite material; the graphene sheet has the advantages of low friction coefficient, good self-lubrication and high mechanical strength. The specific content of graphene sheets is dispersed in UHMWPE, which can form physical intervals in the amorphous region of UHMWPE, reduce the entanglement between molecular chains, and thus improve the melt fluidity and mechanical strength of the ultra-high molecular weight polyethylene composite material; the antioxidant can prevent UHMWPE and HDPE from oxidative degradation and extend the service life of the ultra-high molecular weight polyethylene composite material.

[0026] For example, in the ultra-high molecular weight polyethylene composite material, the mass percentage of ultra-high molecular weight polyethylene may be 20%, 22%, 24%, 26%, 28% or 30%, etc.

[0027] For example, in the ultra-high molecular weight polyethylene composite material, the mass percentage of high-density polyethylene may be 70%, 72%, 74%, 76%, 78% or 80%, etc.

[0028] For example, in the ultra-high molecular weight polyethylene composite material, the mass percentage of graphene sheets can be 0.4%, 0.5%, 0.6% or 0.7%, etc.

[0029] For example, in the ultra-high molecular weight polyethylene composite material, the mass percentage of the antioxidant may be 0.15%, 0.16%, 0.17%, 0.18%, 0.19% or 0.2%, etc.

[0030] In some embodiments, the particle size of the graphene sheet is 7.00 μm-12.00 μm, for example, it can be 7.00 μm, 8.00 μm, 9.00 μm, 10.00 μm, 11.00 μm or 12.00 μm, etc., and the thickness of the graphene sheet is less than 1 nm, for example, it can be 0.3 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm or 0.9 nm, etc. The graphene sheet within the above particle size and thickness range is conducive to the uniform dispersion of the graphene sheet in UHMWPE, so that the ultra-high molecular weight polyethylene composite material has better melt fluidity and mechanical strength.

[0031] In general, ultra-high molecular weight polyethylene (UHMWPE) refers to linear polyethylene with a molecular weight of 3 million to 6 million, and high-density polyethylene (HDPE) refers to a polyethylene with a crystallinity of 80% to 90% and a density of 0.941 g / cm 3 -0.965 g / cm 3 of polyethylene.

[0032] In the present invention, the molecular weight of the ultra-high molecular weight polyethylene is 3 million to 6 million, for example, 3 million, 3.5 million, 4 million, 4.5 million, 5 million, 5.5 million, 6 million, which can give the ultra-high molecular weight polyethylene composite material better wear resistance and mechanical properties.

[0033] In some embodiments, the molecular weight of the high-density polyethylene is 500,000-1,000,000, for example, 500,000, 600,000, 700,000, 800,000, 900,000, or 1,000,000, which can further improve the melt fluidity of the ultra-high molecular weight polyethylene composite material.

[0034] According to the technical solution of the present invention, the antioxidant includes a hindered phenol antioxidant, which has excellent compatibility and thermal stability, can effectively capture and neutralize free radicals, prevent the ultra-high molecular weight polyethylene composite material from degradation, and make the ultra-high molecular weight polyethylene composite material have better antioxidant properties.

[0035] In some embodiments, the melt index of the ultra-high molecular weight polyethylene composite material is 6.7g / 10min-8.5g / 10min. The melt index is an important parameter for measuring the melt flow characteristics of the ultra-high molecular weight polyethylene composite material. When the melt index of the ultra-high molecular weight polyethylene composite material is within the above range, the ultra-high molecular weight polyethylene composite material has excellent melt fluidity, is easy to process, helps to shorten the processing cycle, and improves production efficiency.

[0036] Exemplarily, the melt index of the ultra high molecular weight polyethylene composite material can be 6.7 g / 10 min, 6.9 g / 10 min, 7.1 g / 10 min, 7.3 g / 10 min, 7.5 g / 10 min, 7.7 g / 10 min, 7.9 g / 10 min, 8.1 g / 10 min, 8.3 g / 10 min or 8.5 g / 10 min, etc.

[0037] In a second aspect, the present invention provides a method for preparing the above-mentioned ultra-high molecular weight polyethylene composite material, comprising the following steps: melt-blending ultra-high molecular weight polyethylene, high-density polyethylene, graphene sheets and antioxidants to obtain a blended material, and hot-pressing the blended material to obtain an ultra-high molecular weight polyethylene composite material.

[0038] The ultra-high molecular weight polyethylene composite material prepared by the preparation method has excellent melt fluidity and wear resistance, and the preparation method is simple in process and convenient for industrial production.

[0039] In some embodiments, the preparation method of the ultra-high molecular weight polyethylene composite material includes: first pre-blending UHMWPE and graphene sheets to obtain a pre-blended material; then adding HDPE into the material chamber of an internal mixer for melting, adding the pre-blended material to the HDPE after 20-40 seconds for melt blending, and adding an antioxidant during the melt blending process to obtain a blended material; and then using a closed vulcanizer to hot-press the blended material to obtain an ultra-high molecular weight polyethylene composite material.

[0040] In the embodiments of the present invention, a conventional internal mixer in the art may be used for melt blending, and a conventional closed vulcanizer or other equipment with a hot pressing function may be used for hot pressing processing, without particular limitation.

[0041] In some embodiments, the speed of the internal mixer is set to 10 r / min-20 r / min in the first two minutes, and then increased to 40 r / min-60 r / min, so that the UHMWPE, HDPE and graphene sheets are fully mixed and evenly dispersed, and the viscosity change of the melted blended material during the mixing process is monitored by recording the curve of the torque rheometer.

[0042] In the present invention, the temperature of melt blending is 180-200° C., and the time of melt blending is 5-15 minutes, so that UHMWPE, HDPE, graphene sheets and antioxidant are fully melt mixed.

[0043] In some embodiments, the temperature of the hot pressing molding is 180-200° C. to ensure that the blended material can be completely melted and flowed.

[0044] In some embodiments, the hot pressing molding includes step-by-step hot pressing molding, and the step-by-step hot pressing molding conditions are: first pressurizing to 2MPa-5MPa, 1min-2min later, then pressurizing to 5MPa-7MPa, 1min-2min later, then pressurizing to 8MPa-10MPa, 1min-2min later, then pressurizing to 12MPa-13MPa, 7min-10min later. By gradually increasing the pressure and performing pressure relief and exhaust at each stage, bubbles in the ultra-high molecular weight polyethylene composite material can be effectively removed, and the molding quality of the blended material and the density of the ultra-high molecular weight polyethylene composite material can be improved.

[0045] According to the technical solution of the present invention, the preparation method further comprises the following steps: after hot pressing, the obtained hot pressing product is cold pressed to obtain an ultra-high molecular weight polyethylene composite material. Cold pressing is beneficial to eliminate the residual stress inside the ultra-high molecular weight polyethylene composite material and improve the dimensional stability and mechanical properties of the ultra-high molecular weight polyethylene composite material.

[0046] Furthermore, the cold press molding conditions are: pressurizing to 12MPa-13MPa at 10-30°C and maintaining for 12min-16min, which can further improve the dimensional stability and mechanical properties of the ultra-high molecular weight polyethylene composite material.

[0047] Hereinafter, the present invention will be further described in detail through specific examples.

[0048] The sources of raw materials used in the examples and comparative examples of the present invention are as follows:

[0049] UHMWPE: Shanghai Lianle Chemical Technology Co., Ltd., Lelian 500W;

[0050] HDPE: Qatar Petrochemical Company Limited, Qatar Q500;

[0051] Graphene sheets: Shenzhen Suiheng Graphene Technology Co., Ltd.

[0052] The manufacturers and models of the equipment used in the embodiments and comparative examples of the present invention are as follows:

[0053] Internal mixer: Plasti-Corder type internal mixer from Brabender, Germany;

[0054] Closed-type vulcanizing press: LHHS20 closed-type vulcanizing press of Guangdong Lina Industrial Co., Ltd.

[0055] Example 1

[0056] The preparation method of the ultra-high molecular weight polyethylene composite material of this embodiment comprises the following steps:

[0057] (1) pre-blending 210 g of UHMWPE and 6 g of graphene sheets to obtain a pre-blended material;

[0058] (2) 790 g of HDPE was added into the mixer cavity for melting. After 20 seconds, the pre-blended material and 2 g of antioxidant 1010 were added into the HDPE, and melt-blended at 190° C. for 10 minutes to obtain a blended material.

[0059] (3) The blended material is subjected to step-by-step hot pressing and cold pressing by a closed vulcanizing machine to obtain an ultra-high molecular weight polyethylene composite material.

[0060] The particle size of the graphene sheet is 7 μm-12 μm, and the thickness is less than 1 nm. The molecular weight of UHMWPE is 5 million, and the molecular weight of HDPE is 500,000.

[0061] The temperature of the step-by-step hot pressing molding is 190°C, and the conditions of the step-by-step hot pressing molding are: first pressurize to 3MPa, release and exhaust after 1.5min, then pressurize to 6MPa, release and exhaust after 1.5min, continue to pressurize to 9MPa, release and exhaust after 1.5min, and then pressurize to 12.8MPa, release and exhaust after 10min;

[0062] The cold press molding conditions are: pressurizing to 12.8 MPa at 25°C and maintaining for 15 minutes.

[0063] Example 2

[0064] The preparation method of the ultra-high molecular weight polyethylene composite material of this embodiment comprises the following steps:

[0065] (1) pre-blending 300 g of UHMWPE and 6 g of graphene sheets to obtain a pre-blended material;

[0066] (2) 700 g of HDPE was added into the material chamber of the internal mixer for melting. After 20 seconds, the pre-blended material and 1.5 g of antioxidant 1010 were added into the HDPE, and melt-blended at 180° C. for 10 minutes to obtain a blended material.

[0067] (3) The blended material is subjected to step-by-step hot pressing and cold pressing by a closed vulcanizing machine to obtain an ultra-high molecular weight polyethylene composite material.

[0068] The particle size of the graphene sheet is 7 μm-12 μm, the thickness is less than 1 nm, the molecular weight of UHMWPE is 5 million, and the molecular weight of HDPE is 500,000.

[0069] The temperature of the step-by-step hot pressing molding is 180°C, and the conditions of the step-by-step hot pressing molding are: first pressurize to 3MPa, release the pressure and exhaust after 1.5 minutes, then pressurize to 6MPa, release the pressure and exhaust after 1.5 minutes, continue to pressurize to 9MPa, release the pressure and exhaust after 1.5 minutes, and then pressurize to 13MPa, release the pressure and exhaust after 10 minutes.

[0070] The cold press molding conditions are: pressurizing to 13 MPa at 20°C and maintaining for 15 minutes.

[0071] Example 3

[0072] The preparation method of the ultra-high molecular weight polyethylene composite material of this embodiment is basically the same as that of Example 1. Compared with Example 1, the difference is that in step (1), 210 g of UHMWPE and 4 g of graphene sheets are pre-blended to obtain a pre-blended material.

[0073] Comparative Example 1

[0074] The preparation method of the UHMWPE material of this comparative example comprises the following steps:

[0075] 1000g of UHMWPE was subjected to step-by-step hot pressing and cold pressing in sequence using a closed vulcanizer to obtain a UHMWPE material.

[0076] Among them, the molecular weight of UHMWPE is 5 million.

[0077] The temperature of the step-by-step hot pressing molding is 190°C, and the conditions of the step-by-step hot pressing molding are: first pressurize to 3MPa, release and exhaust after 1.5min, then pressurize to 6MPa, release and exhaust after 1.5min, continue to pressurize to 9MPa, release and exhaust after 1.5min, and then pressurize to 12.8MPa, release and exhaust after 10min;

[0078] The cold press molding conditions are: pressurizing to 12.8 MPa at 25°C and maintaining for 15 minutes.

[0079] Comparative Example 2

[0080] The preparation method of the HDPE material of this comparative example comprises the following steps:

[0081] A closed vulcanizer is used to perform step-by-step hot-pressing and cold-pressing on 1000 g of HDPE to obtain a HDPE material.

[0082] Among them, the molecular weight of HDPE is 500,000.

[0083] The temperature of the step-by-step hot pressing molding is 190°C, and the conditions of the step-by-step hot pressing molding are: first pressurize to 3MPa, release and exhaust after 1.5min, then pressurize to 6MPa, release and exhaust after 1.5min, continue to pressurize to 9MPa, release and exhaust after 1.5min, and then pressurize to 12.8MPa, release and exhaust after 10min;

[0084] The cold press molding conditions are: pressurizing to 12.8 MPa at 25°C and maintaining for 15 minutes.

[0085] Comparative Example 3

[0086] The preparation method of the UHMWPE-HDPE material of this comparative example comprises the following steps:

[0087] (1) 790 g of HDPE was added into the mixer cavity for melting. After 20 seconds, 210 g of UHMWPE was added into the HDPE and melt-blended at 180° C. for 10 minutes to obtain a blended material.

[0088] (2) The blended materials are subjected to step-by-step hot pressing and cold pressing in a closed vulcanizing machine to obtain UHMWPE-HDPE materials.

[0089] Among them, the molecular weight of UHMWPE is 5 million, and the molecular weight of HDPE is 500,000.

[0090] The temperature of the step-by-step hot pressing molding is 190°C, and the conditions of the step-by-step hot pressing molding are: first pressurize to 3MPa, release and exhaust after 1.5min, then pressurize to 6MPa, release and exhaust after 1.5min, continue to pressurize to 9MPa, release and exhaust after 1.5min, and then pressurize to 12.8MPa, release and exhaust after 10min;

[0091] The cold press molding conditions are: pressurizing to 12.8 MPa at 25°C and maintaining for 15 minutes.

[0092] Comparative Example 4

[0093] The preparation method of the ultra-high molecular weight polyethylene composite material of this comparative example is basically the same as that of Example 1. Compared with Example 1, the difference is that in step (1), 210 g of UHMWPE and 2 g of graphene sheets are pre-blended to obtain a pre-blended material.

[0094] Comparative Example 5

[0095] The preparation method of the ultra-high molecular weight polyethylene composite material of this comparative example is basically the same as that of Example 1. Compared with Example 1, the difference is that in step (1), 210 g of UHMWPE and 8 g of graphene sheets are pre-blended to obtain a pre-blended material.

[0096] Performance Testing

[0097] The ultra-high molecular weight polyethylene composite materials, UHMWPE materials, HDPE materials, and UHMWPE-HDPE materials in the embodiments and comparative examples were tested for yield strength, breaking strength, elongation at break, melt index, crystallization behavior, wear amount, and dynamic mechanical analysis. The ultra-high molecular weight polyethylene composite materials, UHMWPE materials, HDPE materials, and UHMWPE-HDPE materials are referred to as samples in the following tests.

[0098] (1) Yield strength, breaking strength and elongation at break: Defect-free samples in the embodiments and comparative examples were selected and 25 mm × 4 mm dumbbell-shaped tensile specimens were cut with a cutter. The specimens were tested using a high-temperature universal material testing machine of model WDL-5000N in accordance with standard GB / T528-2009 at a tensile rate of 20 mm / min. The results are shown in Table 1.

[0099] (2) Melt index: Prepare samples according to GB / T3682.1-2018, and ensure that the samples are properly dried and treated before testing to eliminate the influence of moisture and other volatile substances. Set the temperature of the melt flow rate meter to 190°C.

[0100] The sample is placed in the barrel of the melt flow rate meter and preheated at the set temperature until the sample is completely melted. After the test starts, the sample extruded from the melt flow rate meter is cut off every 1 minute, and the sample extruded in each time interval is collected and weighed. The mass flow rate (MFR) of the sample per unit time (10 minutes) is calculated, that is, the melt index of the sample, in g / 10min. The results are shown in Table 1.

[0101] (3) Crystallization behavior: A differential scanning calorimeter (NETZSCH, 204 F1) was used to study the crystallinity and melting behavior of the samples in the examples and comparative examples. Each sample was heated from room temperature to 190°C at a heating rate of 10°C / min under a nitrogen atmosphere (flow rate of 20 ml / min), and kept warm for 5 min, cooled to 20°C and kept warm for 5 min to eliminate all thermal history, and then repeated the above heating process for a second heating cycle to obtain more accurate crystallinity data. The crystallization enthalpy △H measured by DSC f Calculate the crystallinity of the sample using the following formula:

[0102] X c (%) = △H f / △H 0 f ×100

[0103] Among them, X c is the crystallinity of the sample, △H fis the crystallization enthalpy of the sample, △H 0 f is the theoretical crystallization enthalpy of a perfect polyethylene crystal, △H 0 f Known to be 293 J·g -1 The results are shown in Table 2.

[0104] (4) Wear amount: The wear amount of the samples in the embodiments and comparative examples was tested using a wear tester. The wear tester consists of a swing mechanism and a sample fixture. The initial mass m1 of the sample was measured and recorded. The sample was fixed on the sample fixture of the wear tester. The swing mechanism of the tester was set to perform a sinusoidal reciprocating tilting motion from -33° to +33°. The wear speed was adjusted to 36 times / min. The results are shown in Table 2.

[0105] The wear medium is completely dried silicon carbide particles, and the wear medium includes 70 g of silicon carbide particles with a particle size of 1 mm-3 mm and 50 g of silicon carbide particles with a particle size of 3 mm-5 mm.

[0106] A single-cycle wear test was conducted, with the number of single-cycle wear being 100,000 times. The wear medium was replaced after each 100,000 wear cycles, for a total of three cycles. After each cycle, the sample was removed and cleaned with ethanol, ultrasonically cleaned for 1 hour, cleaned with ethanol, and dried until there was no obvious wear medium residue on the sample surface, and its mass m was measured. x (The mass of the sample after the first cycle is m1, the mass of the sample after the second cycle is m2, and the mass of the sample after the third cycle is m3), wear width d x (wear width d1 of the sample after the first cycle, wear width d2 of the sample after the second cycle, wear width d3 of the sample after the third cycle) and wear length l x (The wear length of the sample after the first cycle is l1, the wear width of the sample after the second cycle is l2, and the wear width of the sample after the third cycle is l3).

[0107] The following formulas were used to calculate the wear amount of the sample after the first cycle (wear amount 1), the wear amount after the second cycle (wear amount 2), and the wear amount after the third cycle (wear amount 3). The results are shown in Table 3.

[0108] Wear x =(m0-m x ) / d x .l x

[0109] (5) Dynamic Mechanical Analysis (DMA): The storage modulus (G') was measured by a DMA tester (TA Q800, TA Corporation, USA) to evaluate the degree of entanglement of the amorphous regions of the samples in the examples and comparative examples in the molten state. In the molten state, a higher G' value generally indicates that the amorphous regions of the sample have a higher degree of entanglement, indicating that the interaction between the molecular chains is stronger.

[0110] The sample was cut into rectangular strips of 10 mm × 4 mm × 2 mm. The test mode was tensile mode, the test temperature was 80°C-180°C, the heating rate was 5°C / min, the oscillation frequency was 1 Hz, the strain amplitude was 0.2%, and the G' of the sample at 100°C, 120°C and 140°C were G' respectively. 100℃ , G' 120℃ , G' 140℃ , the results are shown in Figure 1 and Table 4.

[0111] Table 1

[0112]

[0113] From the analysis of Table 1, it can be seen that the elongation at break of the UHMWPE material in Comparative Example 1 is 276.72%, the melt index is 0 g / 10 min, and it has poor flexibility and melt fluidity; the elongation at break of the HDPE material in Comparative Example 2 is 855.67%, the melt index is 8.35 g / 10 min, and it has excellent flexibility and melt fluidity.

[0114] Compared with Comparative Examples 4-5, the ultra-high molecular weight polyethylene composite materials in Examples 1-3 include a specific content of graphene sheets, and the graphene sheets are uniformly dispersed in the amorphous region of UHMWPE to form physical intervals, reduce the entanglement between UHMWPE molecular chains, and enable the ultra-high molecular weight polyethylene composite materials to have both excellent flexibility and melt fluidity.

[0115] Table 2

[0116]

[0117] From the analysis of Table 2, it can be seen that the ultra-high molecular weight polyethylene composite materials in Examples 1-3 have suitable crystallinity, so that the ultra-high molecular weight polyethylene composite materials have good melt fluidity while maintaining excellent wear resistance.

[0118] Table 3

[0119]

[0120] It can be seen from Table 3 that, compared with Comparative Examples 2-5, the ultra-high molecular weight polyethylene composite materials in Examples 1-3 have better wear resistance.

[0121] Table 4

[0122]

[0123] analyze Figure 1 As shown in Table 4, compared with Comparative Examples 1-5, the ultra-high molecular weight polyethylene composites in Examples 1-3 have a lower storage modulus. This is because the graphene sheets are uniformly dispersed in the amorphous region of UHMWPE, reducing the entanglement between UHMWPE molecular chains.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ultra-high molecular weight polyethylene composite material, characterized in that: Calculated by mass percentage, it includes the following components: 20%-30% ultra-high molecular weight polyethylene, 70%-80% high-density polyethylene, 0.4%-0.7% graphene sheet, and 0.15%-0.2% antioxidant.

2. The ultra-high molecular weight polyethylene composite material according to claim 1, characterized in that: The particle size of the graphene sheet is 7.00 μm-12.00 μm, and the thickness is less than 1 nm.

3. The ultra-high molecular weight polyethylene composite material according to claim 1 or 2, characterized in that: The molecular weight of the ultra-high molecular weight polyethylene is 3 million to 6 million; The molecular weight of the high-density polyethylene is 500,000-1,000,000.

4. The ultra-high molecular weight polyethylene composite material according to any one of claims 1 to 3, characterized in that: The antioxidant includes a hindered phenol antioxidant.

5. The ultra-high molecular weight polyethylene composite material according to any one of claims 1 to 4, characterized in that: The ultra-high molecular weight polyethylene composite material has a melt index of 6.7 g / 10 min-8.5 g / 10 min.

6. A method for preparing an ultra-high molecular weight polyethylene composite material according to any one of claims 1 to 5, characterized in that: The preparation method comprises: Ultra-high molecular weight polyethylene, high-density polyethylene, graphene sheets and antioxidants are melt-blended to obtain a blended material, which is then hot-pressed to obtain the ultra-high molecular weight polyethylene composite material.

7. The preparation method according to claim 6, characterized in that: The temperature of the melt blending is 180-200°C; and / or, The melt blending time is 5 min-15 min.

8. The preparation method according to claim 6 or 7, characterized in that: The temperature of the hot pressing molding is 180-200°C.

9. The preparation method according to any one of claims 6 to 8, characterized in that: The hot pressing forming includes step-by-step hot pressing forming; The conditions for the step-by-step hot pressing molding are: first pressurize to 2MPa-5MPa, release the pressure and exhaust after 1min-2min, then pressurize to 5MPa-7MPa, release the pressure and exhaust after 1min-2min, continue to pressurize to 8MPa-10MPa, release the pressure and exhaust after 1min-2min, and then pressurize to 12MPa-13MPa, release the pressure and exhaust after 7min-10min.

10. The preparation method according to any one of claims 6 to 9, characterized in that: The preparation method further comprises the following steps: after the hot pressing forming, cold pressing the obtained hot pressing forming product to obtain the ultra-high molecular weight polyethylene composite material; The cold press forming conditions are: pressurizing to 12MPa-13MPa at 10-30°C and maintaining for 12min-16min.

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