Jamming in Sheared Foams and Emulsions, Explained by Critical Instability of the Films between Neighboring Bubbles and Drops

Foam and emulsion jamming at low shear rates is explained by considering the thinning dynamics of the transient films, formed between neighboring bubbles and drops. After thinning gradually to a critical thickness, these films undergo an instability transition, which leads to the formation of very thin “black films” providing strong adhesion between the dispersed particles. Analysis shows that such film thickness instability occurs only if the contact time between particles is sufficiently long—an explicit expression for the respective critical shear rate is derived and compared to experimental data.