The Difference Between STYROFOAM and Expanded Polystyrene

Over the years, many have mixed up the brand name STYROFOAM™ with the polymer expanded polystyrene. It is very common to use STYROFOAM™ as a generic term for foam coffee cups and take-out containers, which are typically made of expanded polystyrene. The former is a trademark of the Dow Chemical Company for its extruded polystyrene product, which differs vastly from the generic expanded variety. Although both are rigid, closed-cell, thermoplastic foam products, they are manufactured differently and have unique qualities as well.

STYROFOAM™ brand extruded polystyrene is a result of pressure and extremely hot temperatures. Solid polystyrene crystals, additives and a blowing agent go through an extruder, where they are combined and melted into a viscous, plastic fluid. This mixture is then fed to a die and is shaped, cooled and cut.

Expanded polystyrene, on the other hand, is made of tiny, interconnected beads of polystyrene. During production, pentane gas is dissolved into the polystyrene base to achieve expansion. Once formed, like STYROFOAM™, they can be molded to certain specifications.

Many in the construction business prefer STYROFOAM™ for building insulation due to its high R-value (level of heat resistance), great compression strength, and resistance to moisture. Expanded polystyrene is the ideal choice for those in the market for packaging and soundproofing material, as well as void fill.

The unique characteristics that STYROFOAM™ and expanded polystyrene possess make them ideal for specific purposes, and applications will depend on the project requirements. Seeking the expert advice of trusted suppliers can help determine which foam product best suits a project.