Influences of the size and dielectric properties of particles on electrorheological response

The influences of the size and dielectric properties of particles on the el ectrorheological (ER) response are investigated by computer simulations. Ou r studies show that, in the case of two dimensions, the field-induced shear stress tau of one-component ER fluids can be expressed as tau similar to n sigma(3), where n is the concentration of particle number and a stands for the diameter of particles. Compared with one-component ER fluids, tau is r educed for ER fluids consisting of two kinds of particles with different si zes. When small particles an in the minority, the reduction of the shear st ress can be attibuted to two reasons: one is the weakening of chains, and t he other is related to the shortening and thickening of chains. The latter can explain the reduction of the shear stress for two-component ER fluids, containing a few large particles. For ER fluids consisting of two kinds of particles with different dielectric properties, there is an approximately l inear relation of tau to the particle concentration ratio. [S1063-651X(99)0 5103-X].