Emulsion stability — kinetics of flocculation and coalescence

Abstract

A mathematical model that accounts for the kinetics of flocculation and coalescence or emulsion drops was developed in order to quantify the kinetic stability of emulsions. The model is similar to that developed by van den Tempel with a correction to account for the coalescence in small flocs. The model identifies the conditions under which either the flocculation or coalescence rate controls the kinetics. The model also demonstrates that the rate-controlling mechanism could change from coalescence-rate controlling to flocculation-rate controlling during the course of the emulsion life. An extension to the model for concentrated emulsions was also developed. The model was used to fit two sets of experimental data to determine the kinetic constants that characterize the coalescence in the emulsions.