Effect of Material Properties on the Drainage of Symmetric, Plane Parallel, Mobile Foam Films

Drainage of a mobile, symmetric, plane parallel thin liquid film between two gas bubbles is studied. An analytical solution for the rate of thinning of such a liquid film with an insoluble surfactant and having both film elasticity and surface viscosity is presented for the first time. Analysis is extended to the more general case of a soluble surfactant and compared with previous analyses. Surfactant material parameters affecting the rate of thinning are identified and grouped into a single dimensionless parameter which describes the transition from a mobile to an immobile film. Significant deviation from the Reynolds velocity is found when this dimensionless parameter is small.