Styrene monomer and the polystyrene resin made from the monomer remained as chemical curiosities for 80 years following their discovery in 1845. It wasn’t until 1925 when commercial production of styrene monomer began in Germany and the U.S. that polystyrene attracted interest, and it wasn’t until after World War II when monomer capacity could be diverted from its essential wartime use for styrene-butadiene synthetic rubber that polystyrene became an important plastic. Today, polystyrene is among the most heavily used commodity thermoplastics. Foamed polystyrene is familiar to consumers as foam cups and containers, protective packaging and building insulation. Polystyrene is also widely used in other packaging and foodservice products, such as trays, disposable plates, cutlery and tumblers. Other applications include: automotive parts, toys, housewares, appliance parts, wall tiles, radio and TV housings, furniture, floats, luggage and many more. High molecular weight thermoplastic resins produced generally by the free-radical polymerization of styrene monomer [C6H5CHCH2] which can be initiated by heating alone but more effectively by heating in the presence of free-radical initiator (such as benzoyl peroxide [(C6H5CO)2O2]. Typical processing techniques are modified mass polymerization or solution polymerization, suspension polymerization, and expandable beads for foam.