Polyethylene

A polymerized ethylene resin, used especially for containers, kitchenware, and tubing, or in the form of films and sheets for packaging.

Polyproplyene

Any of various thermoplastic resins that are polymers of propylene. They are hard and tough, and are used to make molded articles and fibers.

Polystyrene

A rigid clear thermoplastic polymer that can be molded into objects or made into a foam that is used to insulate refrigerators.