Suppression of Coalescence in Surfactant Stabilized Emulsions by Shear Flow

Abstract

A study of the shear flow-induced coalescence in a surfactant stabilized, neutrally buoyant emulsion is presented. Evolving drop size distributions are obtained by image analysis. The shear induced coalescence is well described by a population balance model with the coalescence rate taken to be proportional to the Smoluchowski coalescence rate. The coalescence efficiency (ratio of the actual rate to the Smoluchowski rate) is extracted from the experimental data and is found to be independent of drop size. Both theory and experiment show a reduction in the coalescence rate with increasing shear rate. The effect suggests a simple means of stabilizing suspensions during storage.