Correlation of phase inversion temperature with kinetics of globule coalescence for emulsions stabilized by a polyoxyethylene alkyl ether.

The phase inversion temperatures, globule coalescence rates, and long-term stability of oil-in-water emulsions stabilized by polyoxyethylene 4 cetyl ether were measured. Addition of sodium chloride to the aqueous phase depressed the phase inversion temperatures of the emulsions and the cloud point of the surfactant. Linear correlations were obtained between phase inversion temperature and cloud point and also between phase inversion temperature and the logarithm of the globule coalescence rate at constant temperature. This latter finding is consistent with a theory of emulsion type based upon the kinetics of coalescence. The programmed viscometric technique of determining inversion revealed the presence of a liquid crystalline phase below 35 degrees, which contributes significantly to emulsion stability.