Polyurethane is basically 'industrial strength' rubber.
Polyurethanes combine the performance of rubber materials with the processing ease of plastics. Rubber is a thermoset elastomer which is more difficult to process and mold. Polyurethanes are cast in a liquid state, allowing for easier processing and for molding more complex shapes. For abrasion resistance, impact resistance, and durability you can't beat polyurethane elastomers. For applications that require protection from abrasive wear it is an ideal material, outlasting similar parts made from metals or plastics by as much as 20 to 1.