Abstract: Disclosed is an ABS type polyblend composition exhibiting improved physical properties, which comprises from about 5 to 60% by weight of a copolymer of styrene and acrylonitrile; from about 10 to 70% by weight of a graft copolymer of styrene, acrylonitrile, and a butadiene polymer having an average rubber particle size of from about 1 to 10.mu.; and from about 10 to 70% of a high butadiene content backbone copolymer of styrene, acrylonitrile, and a butadiene polymer having an average rubber particle size of less than abut 0.5.mu., the ratios of the backbone copolymer and the styrene-acrylonitrile-butadiene polymer copolymer being adjusted such that from about 15 to 25% by weight of the total butadiene polymer content of the polyblend is provided by the larger rubber particle size graft copolymer.

Abstract: Disclosed is a process for the production of rubber-modified styrene copolymers, particularly high rubber content styrene copolymers, such as high rubber content ABS polymers, by suspension polymerization, comprising suspension polymerizing an admixture of polymerizable materials comprising styrene monomer, rubber polymer, and optional additional monomers copolymerizable therewith; and melt extruding the resultant rubber-modified styrene copolymer under extrusion conditions having a shear force sufficient to homogeneously disperse the rubber phase throughout the copolymer. Through the use of the process of the instant invention, high rubber content styrene copolymers may be produced in a single suspension step, with impact properties and surface appearance comparable to copolymers produced in the conventional two-step polymerization process.