UHMWPE – Why Does Molecular Weight matter? Ans: Abrasion Resistance.

UHMWPE is commonly used for its low coefficient of friction and abrasion resistance, in applications such as wear strips, chain guides, and flow promotion chute and hopper liners for bulk solid material handling.

The abrasion resistance is commonly measured using the “Sand-Slurry” test (ISO 15527). The number is a comparative number (no units), where lower numbers represent lower wear or material loss. For example, a material with a Sand-Slurry number of 90 wears 10% less than a material with a Sand-Slurry number of 100.

Even though applications are unique, the Sand-Slurry number is a good way to compare materials for applications that are subject to abrasion.

What is Molecular Weight, and how does it relate to Abrasion resistance?

The Molecular Weight (units = grams/mol) is the mass in one mole of elementary entities. In the case of UHMWPE, the elementary entity is one polymer chain, and one Mole = 6.02214076 x 1023 (Avogadro’s constant). The longer (and therefore heavier) the polymer chain, the larger the Molecular Weight.

For virgin UHMWPE, larger Molecular Weights typically provide a lower Sand-Slurry number, i.e. better abrasion resistance/less wear.