Acronym and details:   PS

Group:   thermoplastic

Developed:   became a usable material in 1930s but not used commercially until after World War II

Trade names:   Lacqrene; Polystyrol; Styron

Manufacturing process:   usually injection moulding; also extrusion; fabrication: especially cutting and sticking; foaming; thermoforming

Cost:   very low

Colour:   any, including streak and pearlised effects

Transparency:   transparent to opaque

Rigidity:   hard, except when foamed

Feel:   always rigid

Smell:   none

Other:   can be brittle but can be toughened, e.g. high impact polystyrene (HIPS); metallic ring when tapped; good for bonding

Typical uses:   disposable pens and razors; cutlery and vending cups; CD cases; yogurt pots; model kits; insulation and packaging food trays, hamburger and egg boxes, electronic equipment, when foamed

Degradation:   crazing and discolours