Polystyrene is one of the most widely used plastics, the scale being several billion kilograms per year.
•Polystyrene can either be a thermoset or a thermoplastic.
A thermoplastic PS is in a solid (glassy) state at room temperature, but flows if heated above its glass transition temperature of about 100 °C (for molding or extrusion), and becomes solid again when cooled.
PS is economical, and is used for producing plastic model assembly kits, plastic cutlery, CD "jewel" cases, smoke detector housings, license plate frames, and many other objects where a fairly rigid.
•PS Petri dishes and other laboratory containers such as test tubes and microplates.