Ultra-High-Molecular-Weight Polyethylene (UHMWPE, HMPE)

Properties and Applications

Ultra-high-molecular-weight polyethylene (UHMWPE), also known as high-modulus polyethylene (HMPE), is a type of thermoplastic polyethylene having a density in the range of 0.925 - 0.95 g/cm³. Like HDPE, it is often produced by a low temperature Ziegler-Natta polymerization process using an aluminum trialkyl TiCl₄ complex.
UHMWPE has about ten times higher molecular weight than high density polyethylene (HDPE) which is typically in the range of 10⁶ to 10⁷ g/mol.¹ The high molecular weight and high melt viscosity makes the resins unsuitable for melt processing. The most widely used process is cold compaction followed by sintering of the powder at high temperatures.
UHMWPE exhibits excellent impact resistance, high strength and high heat deflection temperature which surpass those of HDPE. Tensile and flexural modulus, however, are typically lower than those of HDPE. This type of polyolefin also resists most chemicals at room and moderate temperatures except aromatic, halogenated hydrocarbons and strong oxidizing agents and a few other chemicals.¹ Due to self-lubrication, parts made from this resin have a very low coefficient of friction and excellent wear and abrasion resistance. 

High molecular weight polyethylene has many uses in the textile industry. The resin is gel-spun into fibers which are used in protective clothing (ballistic vests, cut-resistant gloves), sailcloth, fish netting, and marine cordage. Other noteworthy applications include orthopedic implants, separator for batteries, liners for gravity flow applications (bin, hopper and truck liners), conveying components (bearings, belt and chain guides) and pulleys. UHMWPE resin in powder form is frequently used as an additive in coatings, lubricants, rubbers, and plastics to improve lubrication and abrasion resistance.

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