Modeling and experimental studies of aqueous suspension polymerization processes .3. Mass-transfer and monomer solubility effects

In the suspension polymerization of monomers with significant water solubility, the process behavior is significantly different from bulk polymerization. The effects of monomer solubility in suspension polymerization have been examined using vinyl acetate and comonomers as model systems. At low monomer to mater ratios, suspension polymerization shows an unexpected limiting monomer conversion. For copolymerization, the monomer conversion and copolymer composition results are also different from the bulk model prediction. Factors affecting monomer mass transfer and solubility have been examined. Microgel formation seems to be the major cause. Salts have been used to reduce monomer solubility effects. Good polymer particle size is obtained under the salting conditions so that salting proves to be an effective method of handling monomer solubility problems.