Blends of rigid PVC and polystyrene

Several compatibilizing agents were investigated to stabilize blends of rigid poly(vinyl chloride) and polystyrene. Copolymers of alpha‐methyl‐sytrene and methacrylonitrile were made by emulsion polymerization. These products, with alpha‐methylstyrene contents varying between 50 and 75 weight percent, could be blended with the two primary polymers to produce alloys with good processability and strength. Styrene‐acrylonitrile copolymers with 70 and 75 percent styrene content were also found to provide useful polyblends. All mixtures were opaque. Compositions containing at least 30 weight percent PVC were self‐extingushing. Polystyrene‐poly(vinyl chloride) mixtures with as little as 7.5 weight percent styrene‐acrylonitrile copolymer appear to have adequate mechanical strength and processability for commercial applications. Some end‐uses for variations of these polyblends are suggested.