Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications, including packaging, textiles, stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes. Polypropylene belongs to the polyolefin group.
Polypropylene is normally tough and flexible, especially when copolymerized with ethylene. This allows polypropylene to be used as an engineering plastic. Polypropylene is reasonably economical, and can be made translucent when uncolored, but is not as readily made transparent as polystyrene, acrylic, or certain other plastics. It is often opaque or colored using pigments. Polypropylene has good resistance to fatigue.
Melt processing of polypropylene can be achieved via extrusion and molding. The most common shaping technique is injection molding, which is used for parts such as cups, cutlery, vials, caps, containers, housewares, and automotive parts. Polypropylene is the modular belt material for most common conveying applications.