Extruded polystyrene is a type of insulation material with fine, closed cells, containing a mixture
of air and refrigerant gas. Popularly known by its Dow trademark Styrofoam,
it has a high R-value, good moisture
resistance, and high structural strength compared to other rigid insulation
materials. Both extruded polystyrene and the other common type of polystyrene
foam, expanded polystyrene (EPS),
are used extensively as thermal insulation in industrial, commercial, and
residential construction. Most food service applications including meat
trays, egg cartons, hamburger clam shells, foam plates, and trays are extruded
polystyrene, although disposable coffee cups are made of expanded polystyrene.
Environmentally-damaging chlorofluorocarbons (CFCs) are used in the manufacture of extruded polystyrene, however the
expansion agent for EPS material is pentane.