What is a Polystyrene Foam?

Karyn Maier
Karyn Maier

Polystyrene foam is a type of plastic produced from styrene. It is a lightweight, moisture-resistant material with exceptional insulation properties. Since it is composed of more than 90 percent air, this foam is also remarkably buoyant. It is this characteristic that prompted the U.S. Coast Guard and the U.S. Navy to use this foam to make life rafts and preservers since World War II. Consumers are quite familiar with this material too, although it is commonly mistaken for something else entirely.

Polystyrene foam may be used to make insulation wrap for homes.
Polystyrene foam may be used to make insulation wrap for homes.

Styrofoam™ is the trademarked name for extruded polystyrene foam, an invention of the Dow Chemical Company that has been in production for more than 50 years. Nearly anyone who has purchased coffee “to go” has heard the container being referred to as a Styrofoam™ cup. However, this material has never been used to make disposable coffee cups. For that matter, it’s never been used to make portable picnic coolers either, another misconception. These products are actually made from expanded polystyrene foam (EPS) in the form of beads, commonly known as packaging “peanuts.”

Polystyrene foam may be used as an insulation layer under pavement to prevent the formation of road cracks.
Polystyrene foam may be used as an insulation layer under pavement to prevent the formation of road cracks.

Unlike disposable cups and picnic coolers, which are notably white in color, products made from polystyrene foam are typically blue. It is used to make insulation wrap for residential homes, commercial buildings, and plumbing systems. It is also used in road construction as an insulation layer under pavement to deter the formation of cracks and potholes that occur from seasonal freezing and thawing of the soil beneath.

Polystyrene foam is used to make the hulls of some boats and life rafts.
Polystyrene foam is used to make the hulls of some boats and life rafts.

Polystyrene foam is also made into materials used in craft projects. In fact, florists are familiar with the distinctive crackling sound made when cutting Styrofoam™ or inserting floral stems into it. It is also used to fashion architectural models and as backing for framed photographs and prints. While other forms of this foam are blue in color, the foam made for craft purposes is either green or white.

In terms of environmental impact and hazards to human health, polystyrene foam manufacturing is regarded by the U.S. Environmental Protection Agency as the fifth major producer of hazardous waste. Aside from posing an occupational health risk due to exposure to styrene during processing, there are concerns over polystyrene production contributing to poor air quality. This is due to hydrocarbons escaping during manufacturing and reacting with nitrogen oxides in the air, which forms a pollutant known as tropospheric ozone. In addition, many recycling companies will not accept products made from polystyrene foam left on the curb, presumably because the market for reclaiming this material is limited.

Polystyrene sheets provide excellent insulation properties.
Polystyrene sheets provide excellent insulation properties.
Karyn Maier
Karyn Maier

Contributing articles to wiseGEEK is just one of Karyn’s many professional endeavors. She is also a magazine writer and columnist, mainly for health-related publications, as well as the author of four books. Karyn lives in New York’s Catskill Mountain region and specializes in topics about green living and botanical medicine.

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Discussion Comments

anon355693

Can you tell more about PBFC that is used for building houses more, and explain what is good and bad about it?

anon345207

Can you talk more about the insulation properties of polystyrene?

anon92365

can you fiber glass over polystyrene foam? 2 in.thick closed cell? is it strong enough to stand on and can i use it for a floor in a boat?

anon46503

can pillows made up of polystyrene be washed in the washer?

anon44837

'plastic' is an encompassing term for lots of polymers. polystyrene is a polymer and can be termed 'plastic'. so you could say that it is a plastic foam. foam means that it is porous and contains gas, making it less dense. so 'plastic foam' is just plastic that has had air pumped through it while it is setting.

XX. Ash

anon34439

Is plastic foam the same as polystyrene foam?

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