dispersed-phase, its properties exhibit Newtonian ones, but
The fundamental aspects governing the rheology of water-inin the high concentration range, it behaves as a shear-thinoil emulsions, such as viscosity ratio and morphology were considning fluid (1, 2). Therefore, the volume fraction of the disered. The model developed here is based on the early work of Pal persed phase is the most important factor that influences the and Rhodes (1989) for viscosity equation, combined with the theviscosity of emulsion. ory of Lee and Park (1994) for the morphological contributions.
Unlike a solid-in-liquid suspension, the viscosity of an Thus, the proposed conception enables us to predict not only the emulsion depends on the viscosity ratio of the two fluids.
degree of flocculation but also viscosity ratio and morphological
The overall viscosity of an emulsion is lower than that of a effects. The contribution of secondary morphology caused by the suspension at the same volume fraction, because internal flocculation of droplets on the viscosity of dispersed emulsions has been found by using the factor, 0aq xy /g h (where a is the interfacial circulation inside the droplets reduces the distortion of flow tension, q xy is xy-component of anisotropy tensor, and g h is shear field outside the droplets (1). However, it has been demonrate). However, this approach is only useful for system below the strated that the presence of a surfactant greatly inhibits this maximum random packing concentration. Experimentally, the effect (3). It is important to be able to predict the viscosity bulk rheological properties have been examined under steady and of emulsion, as a function of the viscosity ratio as well as dynamic shear flow to investigate the structure of emulsion. The the dispersed-phase concentration and shear rate. Also, the flocculation-deflocculation transition was observed during the microstructure representing the overall morphological state, shear rate sweep, resulting in instant dilatancy of viscosity near whether it is flocculated or deflocculated, plays an important the critical shear rate g h Γ 100 s 01 . α§ 1997 Academic Press role in determining the emulsion rheology and dynamics.