thermoplastics

thermoplastics, materials that soften or melt when heated and harden when cooled. Thermoplastic polymers consist of long polymer molecules that are not linked to each other. i.e., have no cross-links. They are often supplied as granules and heated to permit fabrication by methods such as molding or extrusion. Thermoplastics include polyethylene, polypropylene, polystyrene, polyester, polyvinyl chloride, acrylics, nylons, spandex-type polyurethanes, and cellulosics.