Styrofoam is a trademarked brand of closed-cell currently made for thermal insulation and craft applications. It is owned and manufactured by The Dow Chemical Company.
In the United States and Canada, the word styrofoam is often incorrectly used as a generic term for expanded (not extruded) polystyrene foam, such as disposable coffee cups, coolers, or cushioning material in packaging, which are typically white and are made of expanded polystyrene beads. This is a different material from the extruded polystyrene used for Styrofoam insulation. The polystyrene foam used for craft applications, which can be identified by its roughness and by the fact that it "crunches" when cut, is moderately soluble in many organic solvents, cyanoacrylate, and the propellants and solvents of spray paint, and is not specifically identified as expanded or extruded. Another tradename for expanded polystyrene is thermacol, originated by BASF.
In 1941, researchers in Dow's Chemical Physics Lab found a way to make foamed polystyrene. Led by Ray McIntire, they "rediscovered" a method first discovered by Swedish inventor Carl Georg Munters. Dow acquired exclusive rights to use Munters' patents and found ways to make large quantities of extruded polystyrene as a closed cell foam that resists moisture.
Styrofoam is composed of ninety-eight percent air, making it light weight and buoyant. Because of its insulating properties and buoyancy, it was adopted in 1942 by the United States Coast Guard for use in a six-person life raft.
Styrofoam has since found a variety of uses. Dow produces Styrofoam building materials, including insulated sheathing and pipe insulation. The claimed R-value of Styrofoam insulation is five per inch.
Dow also produces Styrofoam as a structural material for use by florists and in craft products. Dow insulation Styrofoam has a distinctive blue color; Styrofoam for craft applications is available in white and green.
Styrofoam can be used under roads and other structures to prevent soil disturbances due to freezing and thawing.
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