Home > Case > Content

UHMWPE's extremely high molecular weight and excellent performance

Aug 30, 2019

UHMWPE's extremely high molecular weight (HDPE usually has a molecular weight of only 20,000 to 300,000) gives it excellent performance, and it is a moderately priced and excellent thermoplastic engineering plastic. It has almost the advantages of various plastics, with ordinary polyethylene and Other engineering plastics have unmatched wear resistance, impact resistance, self-lubrication, corrosion resistance, impact energy absorption, low temperature resistance, hygienic non-toxicity, non-adhesion, low water absorption, and low density. In fact, there is currently no single polymer material with so many excellent properties.

Wear resistance

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.

Impact 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 dynamic friction factor of UHMWPE is 1/2 of PA66 and POM under water lubrication conditions, and it is second only to the self-lubricating polytetrafluoroethylene (PTFE) in plastic under no lubrication conditions; When it is operated in sliding or rotating form, it is more lubricious than steel and brass. Therefore, UHMWPE is known as a friction material with very good cost/performance in the field of tribology.

Chemical resistance

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.

Hygienic non-toxic

UHMWPE is hygienic and non-toxic, fully compliant with the standards of the Japan Health Association, and is approved by the US Food and Drug Administration and the US Department of Agriculture for use in food and medicine.

Not sticky

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.


Table 2 compares the density of UHMWPE with other engineering plastics. As can be seen from Table 2, UHMWPE has a lower density than all other engineering plastics, generally 56% lower than PTFE, 33% lower than POM and 30% lower than PBTP, so its products are very light.

Tensile Strength

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.

Other performance

UHMWPE also has excellent electrical insulation properties, better environmental stress crack resistance than HDPE, better fatigue resistance and r-ray resistance than HDPE.