Foam and thin film breakdown processes

The stability of foams depends on the stability of the constituent thin liquid films which are connected through Plateau borders. Likewise, the stability of thin films, separating approaching deformable droplets in emulsions, is directly relevant to emulsion stability. Some aspects of the stability of thin liquid films are conveniently discussed in terms of disjoining pressure isotherms which reflect the nature of the forces acting between the surfaces of the films. During drainage, when the films are relatively thick, the rheological properties, of the individual surfaces of the lamellae can control the rates of film thinning and eventual rupture. The stabilization and layering within thin films, resulting from the presence of micelles or latex particles, continues to be of interest. Foam and film stability can be remarkably dependent on the presence of small particles, of liquid and/or solid form, which indeed are often the main constituents of antifoam formulations.