polyurethanes (pŏlˌēyŏrˈəthānz) [key], group of plastics that may be either thermosetting or thermoplastic. Polyurethane can be made into both flexible and rigid foams. The flexible foam is often used in furniture and automobile cushions, in mattresses, and for carpet backings. The rigid foam is used for the thermal insulation of refrigerators, trucks, and buildings. In the furniture industry the rigid foam is molded into mirror frames, chair shells, and other parts that were formerly made from wood. Some polyurethanes are highly elastic materials that are resistant to chemical attack and to abrasion. They are used in such things as solid rubber tires and shoe heels. Lycra, a fiber used in stretch clothing, is a polyurethane. Polyurethanes are also used as decorative and protective coatings, exhibiting high gloss, hardness, and toughness.
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