Question

why does thermocol contract on heating while other solid expand?

Answer 1

Thermocol is the trade name for the expanded polystyrene (EPS). Expanded polystyrene is produced from a mixture of about 90-95% polystyrene and 5-10% gaseous blowing agent, most commonly pentane or carbon dioxide. The solid plastic is expanded into a foam through the use of heat, usually steam.More than 80% of its apparent volume is air bubbles.When thermocol is heated the polystyrene skin of the bubbles melt, air escapes, and the material shrinks to smaller volume.