Polystyrene, trade name Styrofoam, has a density of 1.05 grams per cubic centimeter. Made up of 95 percent air, polystyrene is used in a wide variety of products, from insulation to foam cups.
Polystyrene is composed of styrene particles that have undergone polymerization. In addition to having been used in the production of videocassettes and audio cassettes, polystyrene is used in mold-formed eating utensils and fresh produce trays. Polystyrene became more widely used in 1937 when Dow Chemical Company found a way to produce polystyrene that was less brittle, easily molded and quickly produced. Chlorofluorocarbons, once used in the production of polystyrene, were removed from the process by the 1980s when it was discovered that CFCs affect the ozone.