Dielectric spectroscopy — a method of investigating the stability of water-oil emulsions

Abstract

Emulsions are thermodynamically unstable systems. Therefore it is of great importance for technical applications to characterize their physical stability. Unfortunately, the most reliable methods of determining the stability of emulsions require long periods of time.

A new method based on dielectric spectroscopy is presented, which permits distinction between stable and unstable water-oil (w/o) emulsions. These measurements register the volume fraction of the inner phase (water) and its changes with time at different locations in the sample.

Simple model emulsions were investigated using this method. Different mechanisms of destroying the emulsion such as sedimentation, flocculation, and coalescence can be identified and these processes can be recorded time-dependently. The results of such measurements allow the prediction of the physical stability of w/o emulsions.

Henkel KGaA, Düsseldorf