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Polystyrene (PS)

The events that led to the development of this versatile and widely-used thermoplastic polymer began in Berlin in the mid-19th century with Eduard Simon and continued almost a century later with German organic chemist and Nobel prize winner Hermann Staudinger. Commercial production of polystyrene commenced in 1930, initiated by Badische Anilin & Soda-Fabrik. Soon enough, the plastic polymer took the world by storm. Fast-forward to World War II, where we meet Ray McIntire, a man on a mission to find a suitable insulator with enough flexibility for his purpose. The accidental result, “Styrofoam”, was ultra-light and incredibly useful, though mainly for packaging and cushioning.

Properties

Polystyrene is most often a homopolymer containing styrene as its monomer. It is synthetic and aromatic, is either thermoset or thermoplastic and either rigid or foamed. Although “Styrofoam”, or foamed polystyrene, is the most well-known form of polystyrene, solid resin polystyrene is found in many thousands of applications as well. In this form, it is brittle, hard, transparent, and can be colored. At room temperature, thermoplastic polystyrene is solid and glass-like, and its melting point of 100°C allows it to flow. It liquifies at around 210-240°C, resets into solid form once cooled, and can be reheated. Thermoset polystyrene, on the other hand, may only be heated once. Foamed polystyrene contains bubbles and is 30 times lighter than solid polystyrene.

Production and Processing

Raw material is extracted from crude oil, distilled, steam-cracked and dehydrated to create styrene, the monomer that makes up polystyrene. After combining the styrene with catalysts under specific heat and pressure conditions in a reactor to facilitate polymerization, polystyrene is produced in pellets that are then subjected to further processing. The end-product is either high impact, general purpose or expandable polystyrene. Foamed polystyrene starts as polystyrene beads that are steamed with hydrocarbon to expand. Then they are cooled and reheated in a mold to expand into the desired shape.

Applications

For packaging and protection of equipment, polystyrene is often the most cost-effective and versatile solution, in particular for food and to cushion fragile goods while in transit. Polystyrene resins are used in household appliances, often for parts that require injection molding, thermoforming or extrusion. Appliance casings and electronic components are often formed from or insulated by polystyrene. In the construction industry, polystyrene is used for insulation, panels, plumbing and lighting fixtures. Kitchen and bathroom accessories and children’s toys are frequently fashioned from polystyrene, as are medical accessories such as trays, tubes, dishes and casings.