Styrofoam

Styrofoam is a trademarked brand of closed-cell extruded polystyrene foam (XPS), manufactured to provide continuous building insulation board used in walls, roofs, and foundations as thermal insulation and as a water barrier. This material is light blue in color and is owned and manufactured by DuPont. DuPont also has produced a line of green and white foam shapes for use in crafts and floral arrangements.

The term Styrofoam is often used in the United States as a colloquial term to refer to expanded (not extruded) polystyrene foam (EPS). Outside the United States, EPS is most commonly referred to as simply "polystyrene" with the term "styrofoam" being used in its capacity to describe all forms of extruded polystyrene, not just the Dupont brand itself. Polystyrene (EPS) is often used in food containers, coffee cups, and as cushioning material in packaging. Styrofoam is, however, a far less dense material than EPS and is more commonly suited to tasks such as thermal insulation.

Additionally, it is moderately soluble in many organic solvents, cyanoacrylate, and the propellants and solvents of spray paint.

History
In the 1940s, researchers, originally at Dow's Chemical Physics Lab, led by Ray McIntire, found a way to make foamed polystyrene. They rediscovered a method first used by Swedish inventor Carl Georg Munters, and obtained an exclusive license to Munters's patent in the United States. Dow found ways to adapt Munters's method to make large quantities of extruded polystyrene as a closed cell foam that resists moisture. The patent on this adaptation was filed in 1947.

Uses
Styrofoam has a variety of uses. Styrofoam is composed of 98% air, making it lightweight and buoyant.

DuPont produces Styrofoam building materials, including varieties of building insulation sheathing and pipe insulation. The claimed R-value of Styrofoam insulation is five per inch.

Styrofoam can be used under roads and other structures to prevent soil disturbances due to freezing and thawing.

DuPont also produces Styrofoam blocks and other shapes for use by florists and in craft products. DuPont insulation Styrofoam has a distinctive blue color; Styrofoam for craft applications is available in white and green.

Environmental issues
The EPA and International Agency for Research on Cancer reported limited evidence that styrene is carcinogenic for humans and experimental animals, meaning that there is a positive association between exposure and cancer and that causality is credible, but that other explanations cannot be confidently excluded.

See also the expansive list of environmental issues of Polystyrene, among which it being non-biodegradable.