Polyurethane, PUR, is a collective name for a large number of materials with varying properties. What they have in common is that they contain urethane groups (-NH COO-). A large number of other chemical groups, for example ester, ether, urea, biuret, allophanate groups and double bonds may be included in the polyurethane molecules. By mixing pigments, fillers, fibers, various additives and other polymers, the properties can be changed, practically indefinitely. There is no other material group that gives the designer as great opportunities as polyurethane (PUR). Polyurethanes can be soft or hard, solid or cellular, high damping or low damping, brittle or impact resistant, have high water absorption or low water absorption.
POLYURETHANES ARE AVAILABLE IN VARIOUS FORMS
Polyurethanes are available as rubber, thermoplastics, thermoelastics, thermosets, cellular plastics, fibers, foils, rocket fuels and as binders for paints, varnishes and adhesives. Depending on the construction, polyurethanes can be processed in different ways. They can be reaction cast with high pressure or low pressure machines, injection molded, extruded, pressed and foamed by several methods.