Emulsification in batch emulsion polymerization

Dispersion of liquid-liquid systems is often applied in industrial processe s such as extraction, suspension, and emulsion polymerization. The influenc e of emulsification of the monomer in the aqueous phase on the course and o utcome of the batch emulsion polymerization of styrene has been studied. A visual criterion was applied for determining the lowest impeller speed for sufficient emulsification (N*). It appeared that in polymerization experime nts under the same conditions, N* was the critical value above which no fur ther increase in polymerization rate was observed. Using a turbine impeller instead of a pitched blade impeller as well as using a larger impeller dia meter provides better emulsification at constant power input. The results i ndicate that scale-up with constant impeller tip speed is most appropriate in case of a turbine impeller. (C) 1999 John Wiley & Sons, Inc.