Polyethylene terephthalate is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination with glass fiber. It is one of the most important raw materials used in man-made fibers.
It is manufactured under trade names Arnite, Impetand Rynite, Ertalyte, Hostaphan, Melinex and Mylar films, and Dacron, Diolen, Terylene & Trevira fibers. 1
1. http://en.wikipedia.org/wiki/Rynite