Interfacial Rheological Properties of Absorbed Surfactant Films with Applications to Emulsion and Foam Stability

This chapter highlights the role that interfacial properties play in determining the stability of foam and emulsion systems. It briefly discusses the interfacial properties that characterize a fluid/ fluid interface, followed by how these properties affect the kinetic behavior of foams and emulsions. The chapter discusses the role of interfacial rheological properties in determining the behavior of thin liquid films that are considered to be model foam and emulsion systems. Gumerman and Homsy examined the stability of a plane-parallel, circular draining film containing enough surfactant to render the film surfaces tangentially immobile. Their analysis included the effect of van der Waals forces, and the aim of their study was to predict the marginally stable film thickness. Rao and co-workers have measured the drainage time and critical thickness of aqueous foam films stabilized by various concentrations of sodium lauryl sulfate and sodium chloride.