In the United States and Canada, the word styrofoam refers to 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.
In 1971 a Dutch marine salvage company, Smit International, used styrofoam balls to refloat part of a wrecked bulk carrier, the London Valour. Smit succeeded in towing the wreck for about 90 miles (140 kilometres) but it then sank, spilling large amounts of Styrofoam on the surface of the sea.
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.
Environmental effects 
The EPA (http://www.epa.gov/chemfact/styre-sd.pdf) and International Agency for Research on Cancer (http://www.inchem.org/documents/iarc/vol82/82-07.html) have determined styrene as a possible human carcinogen. The National Bureau of Standards Center for Fire Research (http://www.highcountryconservation.org/pdf/The%20Facts%20on%20Styrofoam.pdf ) found 57 chemical by-products released during the creation of Styrofoam.
See also 
- List of generic and genericized trademarks
- Structural insulated panel
- Resin identification code
- Building insulation
- National Inventors Hall of Fame
- "STYROFOAM™ - It's Not a Cup" Dow Chemical Company
- Boundy, Ray H.; Amos, J. Lawrence (1991). A History of the Dow Chemical Physics Lab. New York: Marcel Dekker, Inc. pp. 117–128. ISBN 0-8247-8097-3.
- "How is Polystyrene (styrofoam) made?". StyroMelt. Retrieved 2012-23-06.
- Gatti, Carlo (April 2010). "The running aground and the shipwreck of the British cargo ship "London Valour"". Societa' Capitani e Macchinisti Navali – Camogli. Retrieved 12 April 2013.
- Dow Announces New Technology for STYROFOAM Insulation
- "STYROFOAM Brand Foam Crafts". Retrieved 2010-12-31.
- "Geotechnical applications of Styrofoam". Dow Chemical. Retrieved 2009-10-28.
- "Engineering considerations when building on permafrost". Retrieved 2007-08-30.