|P.O. Box 219 Batavia, IL 60510
Most familiar plastics, such as polyethylene and polystyrene, are made from thermoplastic polymers that soften when heated but regain their original properties when cooled. Many plastic objects that have been made by stretching and then cooling a softened polymer exhibit what is called plastic memory—they will return to their original dimensions or shape when heated. Heating a polystyrene cup provides a dramatic illustration of plastic memory.