Dependence of the shear stress on particle properties in electrorheological fluids

By measuring the shear stress of a ferroelectric particle/silicone oil ER f luid varying with the temperature across Tc, the dependence of ER effect on permittivity mismatch is quantitatively obtained. The dielectric property of ferroelectric material behaves a dramatic change at Curie temperature (T c) either in the dielectric constant and the conductivity. TGS and KNO3 fer roelectric particles are chosen for studying the dielectric constant and co nductivity dependence of the shear stress in ER fluids respectively. The me asured results are more reliable, because the conditions, such as size, sha pe, composition of particles, especially chemical nature of particles and i nterface property between particles and liquid, all are same. The available theoretical calculations can not well fit our measured results. In order t o consider the properties of whole suspensions, the orientation of the part icles with spontaneous polarization under an electric filed was studied in advance.