General Description : Polystyrene homopolymer, known as "crystal" polystyrene in the trade, is an amorphous, transparent and colourless commodity thermoplastic that is rigid, relatively hard and brittle. It has good electrical properties, excellent gamma radiation resistance and can be radiation sterilised but has poor chemical and UV resistance. When modified by the incorporation of elastomers, it becomes (high) impact polystyrene or HIPS, which is often opaque. Hence there are a large number of polystyrene grades available commercially.

Applications include housewares, containers, packaging, glazing and light diffusers and, for HIPS, casings, cups, take-out containers and cassette cases. Polystyrene is also widely used as structural foam and expanded into beads for packaging and cushioning.