Polystyrenes

Polystyrenes refers to polystyrene and related polymers derived from the styrene monomer. The term encompasses general-purpose polystyrene (GPPS), high-impact polystyrene (HIPS), and crystalline stereoisomers such as isotactic and syndiotactic polystyrene, as well as foams including expanded polystyrene (EPS) and extruded polystyrene foam (XPS).

Polystyrene is a clear, rigid, lightweight thermoplastic with a relatively high glass transition temperature. The atactic form is amorphous and transparent, while isotactic and syndiotactic polystyrene are crystalline and exhibit higher stiffness and chemical resistance. GPPS is brittle, whereas HIPS incorporates elastomeric rubber particles to improve impact resistance.

Polystyrene is produced by addition polymerization of styrene monomers, typically via free-radical processes in bulk, suspension, or emulsion polymerization. The monomer is derived from ethylbenzene.

Common applications include packaging materials, food-service ware such as cups and cutlery, CD and DVD cases, and consumer electronics housings. EPS and XPS are widely used as thermal insulation and protective packaging due to their cellular structure and low density.

Environmental and safety considerations include limited biodegradability and recycling challenges for PS and especially EPS. Recycling streams exist but are not universal; energy recovery through incineration is common where permitted. Styrene monomer exposure poses health hazards during handling, and proper controls are required in manufacturing environments.