PVC is the most widely used of the amorphous plastics.  PVC is lightweight, durable, and easy to use.  Polyvinyl chloride (PVC) is prepared from the organic compound vinyl chloride (CH2=CHCl).  Chlorine atoms bonded to a molecular carbon string give PVC its strength and flame resistant properties.  PVC for liners is created by softening pure, rigid PVC with chemicals called plasticizers.  Flexible PVC plastic liners are manufactured by extrusion followed with a calendering process to form rolls seven feet wide that can be fabricated into large panels.  The width of the large panels is always in increments of seven feet.