Styrofoam is a trademarked brand of closed-cell extruded polystyrene foam (XPS), manufactured as insulation board used in walls, roofs, and foundations as thermal insulation and water barrier.
The name styrofoam is also used worldwide to refer to another material that is usually white in colour and made of expanded (not extruded) polystyrene foam (EPS). This material is often used in food containers, coffee cups, and as cushioning material in packaging. The trademarked term is used generically although it is a different material from the extruded polystyrene used for Styrofoam insulation.
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