Polypropylene is a plastic polymer, of the chemical designation C3H6. It is used in many different settings, both in industry and in consumer goods. It can be used both as a structural plastic and as a fiber. Polypropylene is very resistant and is the plastic most often used for lids and caps which require a hinging mechanism. Like many plastics, polypropylene has virtually endless uses, and its development has not slowed since its discovery. Whether used for industrial molds, rugged currency, car parts, Tupperware or bags, polypropylene is one of a handful of materials the world is literally built around. (source : wisegeek.com). Moreover PP is a 100% recycable fabric and follows the cradle to cradle theory.