Polystyrene's most common use 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 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 of.
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 as insulation in building structures, as molded packing material for cushioning fragile equipment inside boxes or as packing “peanuts”. Cut-to-fit into any size packaging, Expanded Polystyrene acts as an excellent insulating material.