Thermoplastic molding compositions of rubber modified copolymers of a vinyl aromatic compound and an .alpha.,.beta.-unsaturated cyclic anhydride

A thermoplastic molding composition which comprises (a) from 40-95 parts by weight of a rubber modified copolymer of styrene-maleic anhydride;

• (b) from 5-60 parts by weight of an emulsion graft polymerization product which comprises (1) from 20-80% by weight of a backbone polymer of the units of butadiene or butadiene-styrene wherein the butadiene units are present in quantities of at least 40% by weight of the backbone polymer, (2) 80-20% by weight of an acrylic monomer graft polymerized to (1);
• said acrylic monomer units being selected from the group consisting of lower alkyl methacrylates and alkyl acrylates and (3) 0 to 60% by weight of a styrene monomer graft polymerized to (1) or (2);
• sequentially or simultaneously with the polymerization of (2);
• and (c) from 5 to 50 parts by weight of poly(2,6-dimethyl-1,4-phenylene) ether resin.

A thermoplastic molding composition which comprises:

• (a) from 40-95 parts by weight of a rubber modified copolymer of a vinyl aromatic compound and an .alpha.,.beta.-unsaturated anhydride that contains from 2-25 parts by weight of rubber, 60-99 parts by weight of a vinyl aromatic compound and from 40 to 1 parts by weight of the .alpha.,.beta.-unsaturated anhydride;
• (b) from 5-60 parts by weight of an emulsion graft polymerization product of an acrylic monomer alone or in admixture with a styrene monomer on a rubbery diene homopolymer or styrene-diene copolymer backbone that contains 80-20% by weight of acrylic monomer, 0-60% by weight of styrene and 20-80% by weight of rubbery diene homopolymer or styrene-diene copolymer backbone;
• and
• (c) from 5-50 parts by weight of a polyphenylene ether resin.