UHMWPE's extremely high molecular weight gives it excellent performance, and it is a moderately priced and excellent thermoplastic engineering plastic. It has almost all the advantages of various plastics. It has unmatched wear resistance and resistance to ordinary polyethylene and other engineering plastics. Impact, self-lubricating, anti-corrosion, absorption of impact energy, low temperature resistance, hygienic non-toxic, not easy to adhere, not easy to absorb water, low density and other comprehensive properties. In fact, there is currently no single polymer material with so many excellent properties.
The wear resistance of UHMWPE is the crown of plastic and exceeds some metals. Figure 1 compares the wear resistance of UHMWPE with other materials. As can be seen from Figure 1, the sanding wear index of UHMWPE is only 1/5 of PA66, 1/10 of HEPE and PVC compared with other engineering plastics; 1/7 of carbon steel compared with metal, brass 1/27. Such a high wear resistance makes it difficult to test the degree of wear resistance by the general plastic abrasion test method, and thus a mortar abrasion test device is specifically designed. The wear resistance of UHMWPE is proportional to the molecular weight, and the higher the molecular weight, the better the wear resistance.
The impact strength of UHMWPE is among the best in all engineering plastics. Figure 2 compares the impact strength of UHMWPE with other engineering plastics. It can be seen from Figure 2 that the impact strength of UHMWPE is about 2 times that of impact-resistant PC and 5 times that of ABS. More than 10 times POM and PBTP. The impact resistance is so high that it is difficult to break it by the usual impact test method. The impact strength increases with the increase of the molecular weight, reaches a maximum at a molecular weight of 1.5 million, and then gradually decreases as the molecular weight continues to increase. It is worth noting that it also maintains excellent impact strength in liquid nitrogen (-195 ° C), which is not found in other plastics. In addition, it has a higher surface hardness after repeated impact.
UHMWPE has an extremely low friction factor (0.05 to 0.11), so it is excellent in self-lubricating properties. Table 1 compares the friction factors between UHMWPE and other engineering plastics. It can be seen from Table 1 that the UHMWPE's dynamic rubbing factor is 1/2 of PA66 and POM under water lubrication conditions, and it is the second most self-lubricating polytetrafluoroethylene (PTFE) in plastic under non-lubricated conditions. When it is operated in a sliding or rotating form, it is more lubricious than steel and brass after lubricating. Therefore, UHMWPE is known as a friction material with very good cost/performance in the field of tribology.
UHMWPE has excellent chemical resistance. In addition to strong oxidizing acid, it can withstand various corrosive media (acid, alkali, salt) and organic media (except hydrazine solvent) within a certain temperature and concentration range. It was immersed in 80 kinds of organic solvents at 20 ° C and 80 ° C for 30 days, and there was no abnormality in appearance, and other physical properties were hardly changed.
Impact energy absorption
UHMWPE has excellent impact energy absorption, and the impact energy absorption value is the highest among all plastics, so the noise damping performance is very good and has excellent sound-cutting effect.
Low temperature resistance
UHMWPE has excellent low temperature resistance and is ductile at liquid helium temperature (-269 ° C), so it can be used as a low temperature resistant part for the nuclear industry.
UHMWPE is hygienic and non-toxic and can be used to contact food and medicine.
The surface adsorption capacity of UHMWPE is very weak, and its anti-stick ability is second only to the non-sticky PTFE in plastics, so the surface of the product is not easy to stick with other materials.
Low water absorption
UHMWPE has a very low water absorption rate; generally less than 0.01%, which is only 1% of PA66, so it is generally not necessary to dry before molding.
UHMWPE is relatively low in density compared to other engineering plastics.
Because UHMWPE has the structural features necessary for stretching orientation, it has unrivaled ultra-high tensile strength, so it can produce ultra-high elastic modulus and strength fibers by gel spinning method, and its tensile strength is up to 3 ～3.5GPa, the tensile modulus is as high as 100-125GPa; the fiber specific strength is the highest among all the fibers that have been commercialized so far, 4 times larger than carbon fiber, 10 times larger than steel wire, and 50% larger than aramid fiber.