Emulsion Destabilization by Squeeze Flow

TL;DR

This paper introduces a simple mechanical compression method to destabilize oil-in-water emulsions, revealing that film rupture and coalescence occur through an avalanche-like process independent of electrostatic interactions.

Contribution

It provides a new mechanical approach to study emulsion destabilization and clarifies the rupture mechanism as an avalanche process rather than electrostatic effects.

Findings

Films thin and break at a critical oil/water ratio.

Destabilization occurs via an avalanche-like propagation.

Electrostatic interactions do not influence film rupture.

Abstract

There is a large debate on the destabilization mechanism of emulsions. We present a simple technique using mechanical compression to destabilize oil-in-water emulsions. Upon compression of the emulsion, the continuous aqueous phase is squeezed out, while the dispersed oil phase progressively deforms from circular to honeycomb-like shapes. The films that separate the oil droplets are observed to thin and break at a critical oil/water ratio, leading to coalescence events. Electrostatic interactions and local droplet rearrangements do not determine film rupture. Instead, the destabilization occurs like an avalanche propagating through the system, starting at areas where the film thickness is smallest.