Abstract
Dielectric behaviour of electro-fluids which show the Winslow effect, one of the electro-viscous effect, is studied experimentally. From the experimental results that water film adsorbed to the particles directly affects the surface charge density of electric double layers and makes dielectric constant of electro-fluids increase, the model of electric double layers proposed by Schwarz is able to be applied to the Winslow effect. Using Krieger-Maron's method about non-Newtonian flow, electro-fluids under an electric field are found to be approximated by the Bingham body with the yielding shear stress proportional to the square of electric field strength. Besides, electro-fluids show the negative thixotropy that the viscosity increases with time under an electric field.