Abstract: There is described a method of making a styrene-type polymer composition which comprises a step of suspension polymerizing a styrene-type monomer composition in an aqueous medium comprising water, polyvinyl alcohol and a water-soluble sulfonated polystyrene, a water-soluble sulfonated styrene-maleic anhydride copolymer or a mixture thereof. Optionally, the styrene-type monomer composition may contain a rubbery material as a toughening agent. Optionally, the suspension polymerization step may be conducted subsequent to a prepolymerization step conducted in mass.

Abstract: Expandable styrene-type polymer beads having a short cooling time are made by impregnating the polymer beads, after the substantial completion of the polymerization, in an aqueous suspension medium comprising a suspending agent and about 0.005-0.3%, based on the weight of water, of non-ionic surfactant which is a copolymer of propylene oxide and ethylene oxide having an HLB number of 8-18 and an average molecuar weight of at least 1,000, and by subsequently washing and drying the beads.