#polystyrene  a polymer of styrene; a rigid transparent thermoplastic; "expanded polystyrene looks like a rigid white foam and is used as packing or insulation"
  supertype:  styrene__cinnamene__phenylethylene__vinylbenzene  a colorless oily liquid; the monomer for polystyrene
  subtype:  Styrofoam  (trademark) a light resilient foam of polystyrene

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