Process for producing styrenic/alkenylnitrile copolymers

A process for the continuous polymerization of styrenic and alkenylnitrile monomers to produce a styrenic/alkenylnitrile polymer, comprising the steps of:

• (a) continuously introducing into a reaction vessel to form a reaction mixture, a feed stream comprising a predetermined ratio of styrenic and alkenylnitrile monomers wherein the alkenylnitrile represents from about 10 to about 60 weight percent of the total monomer content;
• (b) subjecting the reaction mixture to conditions of temperature and super atmospheric pressure under which said monomers polymerize to produce a fluid containing styrenic/alkenylnitrile polymer, styrenic monomer, and alkenylnitrile monomer;
• (c) continuously withdrawing at least a part of the produced fluid from the reaction vessel into a first devolatilizer operated at a lower pressure than the pressure in the reaction vessel but above atmospheric and wherein the lower pressure causes a sufficient amount of alkenylnitrile monomers ratio to flash off to restore the styrenic/alkenylnitrile monomers ratio to substantially that of the feed stream;
• (d) thereafter transferring the fluid from the first devolatilizer to a preheater to heat the fluid to a temperature of from about 190.degree. to about 260.degree. C.;
• and
• (e) introducing the polymer fluid into a second devolatilizer operated under partial vacuum to volatilize and separate substantially all of the volatile components therein.