Are you looking for a tough material with high abrasion resistance? The e-beam process can greatly improve the abrasion resistance of Ultra High Molecular Weight Polyethylene.
Ultra High Molecular Weight Polyethylene is also known as UHMWPE. It’s pretty cool stuff. As the name implies, it is polyethylene with really long chains. In fact, its molecular weight range is typically 100 times more than high density polyethylene (HDPE)! This makes it naturally more resistant to abrasion and impact than your typical polyethylenes.
And what you may not have known… Ultra High Molecular Weight PE can be electron beam crosslinked to further improve its already tough properties! This e-beam technique is used for applications requiring excellent abrasion resistance and friction resistance. For example, e-beam crosslinked UHMWPE is used in hip replacement applications where it is critical to have a long wearing part with very little weight loss.
The trick with UHMWPE is that it is also more sensitive to oxidative degradation than typical polyethylenes. This means that the degradation as a result of irradiation in the presence of oxygen occurs instead of the desired crosslinking. This can be overcome by irradiating the part in a low oxygen environment. Also, it helps to anneal (i.e. heat treat) the part in that low oxygen environment after irradiation. Then the UHMWPE part is ready to do its job at that high performance, high abrasion resistance application you’ve developed.
Another thing I should mention, the oxidative degradation to UHMWPE only affects the surface—where the oxygen in the air can penetrate. That is because oxygen only diffuses a short distance into the surface of the part. Oftentimes a part can be machined to remove the a thin outer layer of material that has been oxidized. It’s like an avocado that you cut in half and left in the fridge over the weekend. The surface layer turns brown, but if you cut that thin layer off, the rest is a beautiful green. Just add some lime juice, cumin, salt, a little raw garlic, and you have guacamole—yum!
But if you want to increase the abrasion resistance of your UHMWPE parts, E-BEAM has the recipe to get the toughness you need for your demanding application!
