Linear viscoelasticity of emulsions : I. The effect of an interfacial film on the dynamic viscosity of nondilute emulsions

The dynamic viscosity of nondilute monodisperse emulsions is calculated by using a cell model. Two possibilities for describing the mechanical properties of the interfacial film between the internal and the external phase are considered: (A) the film is assigned a two-dimensional linear viscoelastic behavior and (B) the film is treated as a shell with finite thickness containing a Newtonian liquid. The resulting expressions for the dynamic viscosity show that model B has two relaxation times and model A has at least two or more. If a Voigt-Kelvin model is used to describe the interfacial rheology, model A will also have just two relaxation times. The results obtained may be used to interpret measurements on emulsions in terms of microscopic parameters of these emulsions.