Electrorheological properties of a mixture of two immiscible fluids havingthe same viscosity

We investigated the electrorheological (ER) properties of a mixture of two immiscible fluids having the same viscosity, but different permittivity and conductivity. In this mixture droplets were dispersed; when subjected to a n electric field they became elongated. We observed an ER effect, i.e., an increase in the apparent viscosity following application of an electric fie ld. It was seen from microscopic observation that the ER effect in the mixt ure is brought about by a morphological change, with the interfacial tensio n between the two fluids playing a crucial role. (C) 2001 The Society of Rh eology.