Polyurethanes are generated by poly-addition of isocyanate and polyoles. These components can be mixed to make 2-component resins. In general, the polymers crosslink during the reaction so that further thermoplastic processes are rules out. However, there is also non-crosslinked polyurethane of the group of thermoplastic elastomers (TPE), which is suitable for thermoplastic processing; the elastic properties range from rigid to jelly-like. Isoyanate reacts with water to release CO2, which is used for easy foaming. Soft versions of PUR foam have rubber-like characteristics. Regarding elongation and flexibility they almost reach the performance of crosslinked rubber materials. PUR soft foams are used in various applications for attenuation and padding. They are found in furniture and mattresses, insoles for shoes, and protective components. Furthermore, PUR is used in coatings, adhesives and lacquers, as well as in highly stretchable plastic films. Since most PUR types (aromatic PUR) are sensitive to UV-radiation as well as hygroscopic, their use in outdoor applications is limited; aliphatic PUR, however, is considered weather-resistant.