polystyrene
noun /ˌpɒliˈstaɪriːn/
  /ˌpɑːliˈstaɪriːn/
(also Styrofoam™ especially in North American English)
 [uncountable]- a very light soft plastic that is usually white, used especially for making containers that prevent heat loss- polystyrene cups
 Oxford Collocations DictionaryPolystyrene is used before these nouns:- cup