Features of UHMWPE Sheets

Release time:

2022-07-12

Ultra-high molecular weight is the distinguishing feature of this polymer, which has a molecular weight of 3 to 6 million, compared to 300,000 to 500,000 for high-density polyethylene resins. This difference is to ensure that UHMWPE has sufficient strength to achieve abrasion and impact resistance not possible with other lower polymer products. The ultra-high molecular weight of ultra-high molecular weight polyethylene means that it does not melt and flows like a liquid, so the processing method is derived from powder metal technology. Traditional plastic processing techniques, such as injection molding, blow molding and heat setting, cannot be applied to UHMWPE. Extrusion is the most common process used for this resin, which produces a tougher product.

The extremely high molecular weight of UHMWPE gives it excellent performance, and it is a thermoplastic engineering plastic with moderate price and excellent performance. It almost concentrates the advantages of various plastics. Impact, self-lubricating, corrosion resistance, impact energy absorption, low temperature resistance, hygienic and non-toxic, not easy to adhere, not easy to absorb water, low density and other comprehensive properties. In fact, there is no simple polymer material with so many excellent properties.

Abrasion resistance
The wear resistance of UHMWPE ranks first in plastics and exceeds that of some metals. Figure 1 shows the comparison of wear resistance between UHMWPE and other materials. As can be seen from Figure 1, compared with other engineering plastics, the mortar abrasion index of UHMWPE is only 1/5 of PA66, 1/10 of HEPE and PVC; compared with metal, it is 1/7 of carbon steel, brass 1/27 of . Such a high wear resistance makes it difficult to test its wear resistance by the general plastic wear test method, so a mortar wear test device is specially designed. The abrasion resistance of UHMWPE is proportional to the molecular weight. The higher the molecular weight, the better the abrasion resistance.

impact resistance
The impact strength of UHMWPE ranks among the best among all engineering plastics. Figure 2 shows the comparison of the impact strength of UHMWPE and 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 that of 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 the maximum value when the molecular weight is 1.5 million, and then gradually decreases with the increase of the molecular weight. It is worth pointing out that it can also maintain 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.

self-lubricating
UHMWPE has a very low coefficient of friction (0.05 to 0.11), so it has excellent self-lubricating properties. Table 1 is the comparison of friction factor between UHMWPE and other engineering plastics. As can be seen from Table 1, the dynamic friction factor of UHMWPE is 1/2 of that of PA66 and POM under water lubrication conditions, and it is second only to polytetrafluoroethylene (PTFE), which has the best self-lubricating properties in plastics under non-lubricated conditions. ; When it works in sliding or rotating form, the lubricity is better than that of steel and brass with lubricating oil. Therefore, in the field of tribology, UHMWPE is known as a very ideal friction material in terms of cost/performance.

chemical resistance
UHMWPE has excellent chemical resistance, in addition to strong oxidizing acid, it can resist various corrosive media (acid, alkali, salt) and organic media (except tea solvent) within a certain temperature and concentration range. It has been immersed in 80 kinds of organic solvents at 20 °C and 80 °C for 30 days, and there is no abnormal phenomenon on the surface, and other physical properties are almost unchanged.

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