Patent ID: 7737249

Claim:
A process for the devolatilization of a polymer of styrene with an unsaturated dicarboxylic acid anhydride of 4 to 8 carbon atoms having low volatiles, which comprises forming a copolymer of styrene with the half ester of a volatile alcohol of 1 to four carbon atoms and having a boiling point below that of styrene monomer with the anhydride of the unsaturated dicarboxylic acid in a polymerization reactor, said copolymer having from 6 to 55 wt % of a volatile organic content, subjecting the resulting copolymer to devolatilization at temperatures between 200 to 260° C. under reduced pressure conditions until the half ester content is below 0.2% as measured by IR, and recovering a polymer of styrene and the dicarboxylic acid anhydride having a styrene content of less than 400 ppm.