Compositions of a polyphenylene ether resin and an aromatic alkenyl resin that is modified by rubber particles in the form of bundles of rubber fibers of rubber sheets

A thermoplastic molding composition which comprises:

• (a) a polyphenylene ether resin;
• and
• (b) a polymeric composition of
• a polymer of at least one monoalkenyl aromatic monomer having dispersed therein, an amount sufficient to toughen said polymer, of a diene rubber, said rubber being dispersed as crosslinked rubber particles and being grafted with said monomer as polymer and having occluded therein said polymer, said particles having a weight average diameter of from 0.5 to 10 microns, said rubber being structured in a morphological form comprising aggregations of rubber fibers, aggregations of rubber sheets or mixtures thereof said polymeric composition being prepared by continuously polymerizing a solution of a monoalkenyl aromatic monomer and a diene rubber under catalytic conditions with back mixed agitation to about 10 to 50% conversion;
• thereafter discontinuing said back mixed agitation and continuing the polymerization of said solution until the monomer is substantially polymerized;
• then heating and separating said polymeric composition from unpolymerized monomer.

A thermoplastic molding composition which consists essentially of:

• (a) 20 to 80 parts by weight of a poly(2,6-dimethyl-1,4-phenylene) ether resin;
• (b) from 80 to 20 parts by weight of a polymeric composition consisting essentially of a polymer of styrene monomer having dispersed therein, an amount sufficient to toughen said polymer, of a diene rubber, said rubber being dispersed as crosslinked rubber particles and being grafted with said monomer as polymer and having occluded therein said polymer, said particles having a weight average diameter of from 0.5 to 10 microns, said rubber being structures in a morphological form comprising aggregations of rubber sheets, aggregations of rubber fibers or mixtures thereof, said polymeric composition being prepared by continuously polymerizing a solution of styrene monomer and a diene rubber under catalytic conditions with back mixed agitation to about 10 to 50% conversion;
• thereafter discontinuing said back mixed agitation and continuing the polymerization of said solution until the styrene monomer is substantially polymerized;
• then heating and separating said polymeric composition from unpolymerized styrene monomer.