Rheological properties of highly concentrated fluorinated water-in-oil emulsions

Abstract

A new rheological model for highly concentrated emulsions containing 77–98% of the dispersion phase is suggested which relates the macroscopic functional properties of these systems (elasticity modulus, yield stress and yield strain) to the microscopic physicochemical parameters (droplet size, interfacial tension, surface forces acting in thin liquid films, specific surface of these films, adhesion force between the droplets, their deformability, etc.). Whereas Princen’s model describes only the effect of the capillary pressure and the volume fraction of the internal phase on the elasticity modulus of such emulsions, the new model also predicts the effect of the adhesion free energy between the droplets (or the contact angle between the droplets) on the elasticity modulus and the yield stress and strain of these emulsions. The model proposed is applied to explain and systematize the effect of physico-chemical parameters on the rheological properties of highly concentrated fluorinated water-in-oil emulsions.