Tech Talk Blog

UHMW Polyethylene is an interesting material in the polymer world.  It’s one of the lowest cost plastics on the market yet it offers some properties that few other polymers do. UHMW is best known for it’s abrasive wear resistance and impact strength but even within this small polymer family there are variations. UHMW stands for ultra high molecular weight and under this description UHMW is produced with a molecular weight range of 3.5 to 6 million. The molecular weight has a fairly dramatic impact on several key properties. For instance, a 4 million molecular weight grade has an abrasion resistance of 100 when measured using a sand slurry test. A 6 million molecular weight is 75 which is a further 25% improvement! Compare this with steel which has a resistance of 160 and you can see why UHMW is the material of choice for abrasive wear environments.

There are several other variations on UHMW including cross linked, glass and moly enhanced and even a high temperature grade.

Check out our Materials Resources Guide to see the entire selection.

We have recently developed a new adhesive for UHMW adhesion. This adhesive is a hot melt adhesive with a glass transition (Tg) of -4 F and a shear failure at 246 F. This means that the hot melt adhesive can expand and contract with the UHMW when bonded to a rigid backing (i.e. UHMW bonded to steel). The use of mechanical fasteners to hold down large pieces of UHMW and the problems of buckling are nearly eliminated. Moreover, the UHMW needs only to be clean for the adhesive to work effectively; no surface treatments or special primers are needed. Our lab tests have shown bonding UHMW to steel in lap shear:

Max (psi) = 83.928         Break (psi) = 75.685     Ext @ Brk = 0.131 in

Other adhesive in development is a new epoxy designed for underwater applications to compliment our existing epoxy product line. Specifically, this underwater epoxy is engineered for submerged bearings for water treatment plants or anywhere where our bearing are used or exposed to water or washing.

You want to learn a little more about surface modification, right?

What say ‘ye?