Polystyrene (PS)

Polystyrene is a polymer made from the monomer styrene.Polystyrene is a hard plastic, colorless and with limited flexibility. It can be cast into molds with fine detail. Polystyrene can be transparent or can be made to take on various colors. It is economical and is used for producing plastic model assembly kits, plastic cutlery, CD jewel cases, and many other objects where a fairly rigid, economical plastic of any of various colors is desired.

Polystyrene's most common use, however, is as expanded polystyrene (EPS). Expanded polystyrene is produced from a mixture of about 5-10% gaseous blowing agent and 90-95% polystyrene by weight, most commonly pentane or carbon dioxide. The solid plastic is expanded into a foam through the use of heat, usually steam. Extruded polystyrene (XPS), which is different from expanded polystyrene, is commonly known by the trade name Styrofoam. Styrofoam is the lightweight material of which coffee cups and takeaway food containers are made. The voids filled with trapped air give it low thermal conductivity. This makes it ideal as a construction material and it is used in structural insulated panel building systems.

It is also used as insulation in building structures, as molded packing material for cushioning fragile equipment inside boxes, as packing , as non-weight-bearing architectural structures , and also in crafts and model building, particularly architectural models. Expanded polystyrene used to contain CFCs, but other, more environmentally-safe blowing agents are now used.