Before you understand this polymer you must understand what vinyl is. Vinyl is an ethene molecule in which one hydrogen atom has been removed and has the structure: H2C=CH-. You can see that the molecule has a free bond which will allow it to bond to another atom. In this monomer that element is chlorine.

Polyvinyl chloride (commonly called PVC) is a polymer that is produced from the monomer monochloroethylene (also known as vinyl chloride). This monomer is produced by reacting ethene (H2C=CH2) with chlorine which causes the one of the hydrogen atoms to be replaced by a chlorine atom.

In the polymerization of PVC, one of the bonds between the carbon atoms breaks and bonds to the vinyl chloride molecule next to it. This makes a continueous chain of H2C-CHCl molecules.

Polyvinyl chloride is most commonly found in PVC pipes. For centuries, water pipes in home were made of lead. Today's PVC pipes are cheaper, lighter and inert.