Polyethylene sheets are divided into high-pressure LDPE and low-pressure HDPE. They have advantages such as non-toxic, smooth surface, flatness, corrosion resistance, excellent electrical insulation properties, and good low-temperature performance. They are widely used in industries such as chemicals and electricity. HDPE sheets can also be used as engineering plastics in machinery and chemical equipment.
   
    1. Improved wear resistance. One remarkable property of high molecular weight polyethylene sheets is their extremely high wear resistance, which is very valuable in many engineering applications. Among all plastics, its wear resistance is the best, even surpassing many metal materials (such as carbon steel, stainless steel, bronze, etc.). As the molecular weight of polyethylene increases, the material becomes more wear-resistant.
   
    2. Extremely high impact resistance. The impact strength of polyethylene sheets is related to their molecular weight. When the molecular weight is below 2 million, the impact strength increases with the molecular weight, reaching a peak around 2 million. Beyond this point, further increases in molecular weight may actually decrease impact strength. This is due to the molecular chains interfering with their crystalline structure, resulting in large amorphous regions within the macromolecules that can absorb substantial impact energy.
   
    According to literature, the impact strength values of polyethylene and other plastics measured by the ASTM-D256 method show that ultra-high molecular weight polyethylene’s room temperature impact resistance rivals that of impact-resistant polycarbonate, which is commonly used in engineering plastics. Ultra-high molecular weight polyethylene maintains good impact resistance even at low temperatures of -40°C, and can still exhibit considerable impact resistance at temperatures as low as -269°C. This excellent low-temperature characteristic expands the application of ultra-high molecular weight polyethylene to low-temperature engineering fields.
   
    3. Very low friction coefficient. Ultra-high molecular weight polyethylene is highly wear-resistant, has a low friction coefficient, and possesses good self-lubrication properties, making it an ideal material for bearing sleeves, sliding blocks, and liners.
   
    Using ultra-high molecular weight polyethylene as friction components in equipment can not only enhance wear resistance but also achieve energy-saving effects.
   
    4. Good chemical corrosion resistance. Ultra-high molecular weight polyethylene has good chemical corrosion resistance; it is resistant to all alkaline and acidic solutions except for concentrated nitric acid. It can be applied in concentrations at temperatures of up to 80°C, remains stable in <20% nitric acid, and <75% sulfide solutions, and is also stable to water and liquid detergents.
   
    However, ultra-high molecular weight polyethylene is prone to swelling in aromatic or halogenated compounds (especially at higher temperatures), so caution is advised during use.
   
    5. Very low water absorption. Ultra-high molecular weight polyethylene has a very low water absorption rate; it is almost non-absorbent and does not swell in water, significantly lower than nylon's water absorption.
   
    6. Thermal properties. According to ASTM (load 4.6kg/cm²) testing, the heat distortion temperature is 85°C. Under lighter loads, the use temperature can reach 90°C, and under special circumstances, it can be used at higher temperatures. Due to the excellent toughness of ultra-high molecular weight polyethylene, its low-temperature performance is also outstanding, retaining some ductility at -269°C without signs of brittleness.
   
    7. Electrical properties. Ultra-high molecular weight polyethylene exhibits excellent electrical properties over a wide temperature range, with a volume resistivity of 10^18 cm and a breakdown voltage of 50 kV/mm, and a dielectric constant of 2.3. Its electrical properties vary very little across a broad range of temperatures and frequencies. It is well-suited as structural material in electrical engineering and for use in paper mills.
   
    8. Non-toxic. Ultra-high molecular weight polyethylene is odorless, tasteless, and non-toxic, with no corrosive properties, possessing physiological cycle and adaptability. It is approved by the FDA and USDA for use in contact with food and pharmaceuticals.
   
    These characteristics, especially wear resistance, impact resistance, and self-lubricating properties, make it one of the best materials in engineering plastics.