Forms produced
Polystyrene is commonly injection molded, vacuum formed, or extruded, while expanded polystyrene is either extruded or molded in a special process. Polystyrene copolymers are also produced; these contain one or more other monomers in addition to styrene. In recent years the expanded polystyrene composites with cellulose[18][19] and starch[20] have also been produced. Polystyrene is used in some polymer-bonded explosives (PBX).