Some aspects of semi-continuous emulsion copolymerization

A semi-continuous emulsion copolymerization of acrylic monomers was investigated. Under the conditions used, the polymerization rate was equal to the rate of feeding of monomers and a steady state with a constant ratio of free monomers was reached. “Effective” reactivity ratios were calculated for several couples of monomers. Significant differences in the particle size distribution were found with monomers of different polarity. The extent of particle flocculation during the process was affected by the emulsifier distribution between the initial reactor charge and the monomer emulsion as well as by the electrolyte concentration. The tendency of particles to flocculate decreased with the increasing concentration of carboxylic groups on the particle surface. A different extent of acid hydrolysis of ester groups was observed by emulsion polymerization of various acrylic monomers.