Bulk Terpolymer Composition Prediction from Copolymer Reactivity Ratios

Abstract

ABSTRACTBulk terpolymerization of butyl acrylate (BA), methyl methacrylate (MMA) and vinyl acetate (VAc) up to full conversion levels was studied at BA/MMA/VAc initial mass ratios of 20/50/30, 50/20/30, 20/60/20, 60/20/20, 10/40/50, and 40/10/50. The experiments were carried out to high conversion levels at 50°C with an initiator concentration of 0.071 mol/L (2,2'-azo-(bis)isobutyronitrile) and a chain transfer agent concentration of 0.0058 mol/L (n-dodecyl mercaptan). For each experiment, samples were analyzed for conversion by gravimetry and for composition by proton nuclear magnetic resonance (1H-NMR) spectroscopy.The overall rate of polymerization was greatly influenced by the amount of BA in the feed and to a lesser degree by the ratio of acrylic monomers (BA + MMA) to VAc in the feed. Using reactivity ratios previously estimated from low conversion bulk copolymerization experiments, the bulk terpolymerization composition data were well predicted by terminal model kinetics up to high conversion levels.