VAPOR-LIQUID-EQUILIBRIUM OF METHYL-METHAC RYLATE AND POLYMETHYL METHACRYLATE FOR ESTIMATION OF DEVOLATILIZATION ABILITY OF VENT EXTRUDER

The chi-parameter in the Flory-Huggins equation of methyl methacrylate and polymethyl methacrylate was determined to be chi=0.33, from the o bservation of vapour pressure of the reaction mixture in a pilot scale reactor for continuous bulk polymerization of methyl methacrylate. Th e monomer content of the polymer solution flushed from the pressurized heat exchanger to the vent extruder almost agreed with the equilibriu m concentration calculated from the Flory-Huggins equation. The monome r content of the resulting pellet (0.15 similar to 0.37%) was far from the equilibrium concentration (0.02%) at the front vent, suggesting t hat the monomer content must be decreased by improvement of the screw design.