PVC, a synthetic resin made from the polymerization of vinyl chloride. Second only to polyethylene among the plastics in production and consumption, PVC is used in an enormous range of domestic and industrial products, from raincoats and shower curtains to window frames and indoor plumbing. A lightweight, rigid plastic in its pure form, it is also manufactured in a flexible “plasticized” form.

Vinyl chloride (CH2=CHCl), also known as chloroethylene, is most often obtained by reacting ethylene with oxygen and hydrogen chloride over a copper catalyst. It is a toxic and carcinogenic gas that is handled under special protective procedures. PVC is made by subjecting vinyl chloride to highly reactive compounds known as free-radical initiators. Under the action of the initiators, the double bond in the vinyl chloride monomers (single-unit molecules) is opened, and one of the resultant single bonds is used to link together thousands of vinyl chloride monomers to form the repeating units of polymers (large, multiple-unit molecules).