page_title: Polystyrene
section_title: Foams
hierarchical_section_title: Polystyrene / Forms produced / Foams
caption_attribution_description: Deutsch: Verpackungsmaterial aus Polystyrol English: Close up of expanded polystyrene packaging Italiano: Imballaggio in Polistirene
context_page_description: Polystyrene is a synthetic aromatic hydrocarbon polymer made from the monomer known as styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and rather brittle. It is an inexpensive resin per unit weight. It is a rather poor barrier to oxygen and water vapour and has a relatively low melting point. Polystyrene is one of the most widely used plastics, the scale of its production being several million tonnes per year. Polystyrene can be naturally transparent, but can be coloured with colourants. Uses include protective packaging, containers, lids, bottles, trays, tumblers, disposable cutlery and in the making of models.
  As a thermoplastic polymer, polystyrene is in a solid state at room temperature but flows if heated above about 100 °C, its glass transition temperature. It becomes rigid again when cooled. This temperature behaviour is exploited for extrusion and also for molding and vacuum forming, since it can be cast into molds with fine detail.
  Under ASTM standards, polystyrene is regarded as not biodegradable.
context_section_description: Polystyrene foams are 95-98% air. Polystyrene foams are good thermal insulators and are therefore often used as building insulation materials, such as in insulating concrete forms and structural insulated panel building systems. Grey polystyrene foam, incorporating graphite has superior insulation properties.
  PS foams also exhibit good damping properties, therefore it is used widely in packaging. The trademark Styrofoam by Dow Chemical Company is informally used (mainly US & Canada) for all foamed polystyrene products, although strictly it should only be used for "extruded closed-cell" polystyrene foams made by Dow Chemicals.
  Foams are also used for non-weight-bearing architectural structures (such as ornamental pillars).
caption: Closeup of expanded polystyrene packaging
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