Interfacial Rheology and Its Application to Industrial Processes

Abstract

In practical systems containing liquids, the interfaces are subjected to disturbances from equilibrium. Changes in shape and area of an interface lead to the concepts of interfacial shear and dilatational rheology and these are explained. Methods for measuring the appropriate interfacial rheological parameters are described and the relaxation mechanisms responsible for this behaviour are discussed. An important aspect of interfacial rheology is the Marangoni effect in which monolayer material moves in response to local differences in surface pressure. The motion is coupled to the adjacent liquid in the bulk phases and this has important consequences in such processes as film thinning, foam stability, droplet coalescence and wave damping, of all which are illustrated.