Polyurethane
Polyurethanes fall into two main classes; polyester (AU) and polyether (EU). These materials have outstanding tensile strength and abrasion resistance. They also have good resistance to oxidation, ozone and petroleum based fuels and oils. Polyesters have physical properties slightly superior to those of polyethers. Electrical properties are fairly good.
Unlike polyethers, polyesters can be affected by hot water and high humidity and their resistance to acids and alkalis is low. Maximum operating temperatures should not significantly exceed ambient. Compression set and creep properties are only fair. In view of the high hysteresis (damping) of most polyurethanes, care must be taken for applications involving high frequency deformation and tyre/wheel speeds of over 8 mph.
As these materials are liquid cast, tooling prices tend to be lower than for heat and pressure moulded rubbers.
Typical applications include abrasion-resistant coatings and linings, diaphragms, gaskets, haul-off pads, hoses, seals and tyres/wheels.
