A polymer is a chemical compound usually made up of a large number of identical components (monomers) linked together into long molecular chains.
马项目de from polyethylene and polypropylene are familiar types of polymers, as are those from polystyrene and polyvinylchloride (PVC).
Many polymers soften when heated and can be moulded into many shapes and in some cases drawn into fibres. These are called thermoplastics, or plastics for short.