The copolymerization of butyl acrylate/methyl methacrylate at elevated temperatures.

Abstract

High temperature multi-component polymerizations have prompted a great deal of interest on the part of the paints, coatings and adhesives industry. Due to this interest, a study of the kinetics of bulk and solution butyl acrylate/methyl methacrylate (BA/MMA) copolymerization was performed over a wide range of temperatures. Reactivity ratios for the bulk and solution (in toluene) BA/MMA copolymer system were estimated for reaction temperatures of 60$\sp\circ$C to 140$\sp\circ$C and exhibited a weak temperature dependence. These parameters increased with increasing temperature which signaled a tendency of both monomers to homopolymerize. The bulk reactivity ratios were comparable to those estimated in the solution experiments and were used to successfully predict copolymer composition up to high conversions of monomer to polymer for various reaction conditions. Conversion profiles followed a typical s-shaped diffusion-controlled polymerization curve. The rate of polymerization increased with increasing temperature. Composition drift was determined to be significant at 40 to 50 wt% conversion for high and low temperatures. The use of solvent altered the conversion profiles by delaying the onset of the gel effect. However, the solvent did not affect composition and molecular weight profiles. All data obtained concurred with classical kinetic trends. Depropagation, which often plays a role at higher temperatures, was not observed for the BA/MMA copolymer system. A study of other copolymer systems that were prone to higher rates of depropagation was also performed in order to ascertain whether model discrimination could be carried out using composition data.