Abstract: The invention relates to a blend, based on polystyrene and/or impact resistant polystyrene, which is stress-corrosion, impact and cold resistant and flame retardant.The blend according to the invention contains 50 to 98 mass % of polystyrene or impact resistant polystyrene, 0.01 to 15 mass % of zeolites with a pore size above 0.43 nm, 2 to 18 mass % of a styrene/butadiene block copolymer, 0 to 15 mass % of a flame retardant and 0 to 2 mass % of a surface-active agent.The properties of the blend can be adjusted between wide limits by a suitable selection of the quality and quantity of the components.The blend can be prepared by the processors themselves, whereby the selection of the available polystyrene types can be considerably increased.