Polymer blends with improved hydrolytic stability

A thermoplastic polymeric composition comprising, in admixture, (a) a linear aromatic polyester prepared by transesterification of monomer reactants consisting essentially of a bisphenol and a diphenyl ester of an aromatic dicarboxylic acid, and (b) and MBS polymer prepared by graft polymerization of methyl methacrylate, or mixture thereof with a minor proportion of an ethylenically unsaturated comonomer, copolymerizable with said methacrylate monomer, in the presence of a polybutadiene or a butadienestyrene trunk copolymer rubber or by blending a methyl methacrylate/styrene copolymer with polybutadiene or a copolymer of butadiene.

A process for improving the hydrolytic stability of a linear aromatic polyester resin of component monomers consisting essentially of a bisphenol and a dicarboxylic acid which comprises adding from about 1 to about 99 parts by weight of an MBS polymer per 100 parts by weight of the resin mixture to said polyester, said MBS polymer being prepared by graft polymerization of methyl methacrylate, or mixture thereof with a minor proportion of an ethylenically unsaturated comonomer, copolymerizable with said methacrylate monomer, in the presence of a polybutadiene or a butadienestyrene trunk copolymer rubber or by blending a methyl methacrylate/styrene copolymer with polybutadiene or a copolymer of butadiene.