Abstract: Disclosed is a process for producing a laminate having at least three layers comprising a base layer of polystyrene, an intermediate layer of an ABS polymer and a third barrier layer of a vinyl chloride or vinylidene chloride polymer comprising the steps of co-extruding through a single die orifice a heat plastified composite structure comprising a base layer of polystyrene and a surface layer of an ABS polymer and thereafter laminating a preformed layer of a barrier material polymer to the ABS surface layer of the co-extruded composite.

Abstract: A process for the manufacture of profiled products by extruding in a substantially non-expanded state an expandable styrene polymer composition through a die orifice having the desired profile and subsequently passing the extruded material through a sizing member wherein it expands to the desired profile and cross-section to produce an article having a porous inner cross-section and a solid, non-foamed outer layer and wherein the styrene polymer composition employed is one containing from about 0.2 to 1.0 parts by weight of an alkaline earth metal carbonate blowing agent and from about 0.2 to 1.0 parts by weight of an organic acid per 100 parts by weight of styrene polymer.