Enhancing yield stress of electrorheological fluids with liquid crystal additive

The enhancement of yield stress of NaY/insulating oil electrorheological (ER) fluid is found by adding a liquid crystal additive with a higher dielectric constant than that of the carrier fluid. The yield stress increases with additive's concentration and saturates at high concentrations. A polarization model has been suggested to understand the role of the additives. The theoretical calculations agree with our experiments very well. We show that adding a small amount of additive with a high dielectric constant can drastically improve the yield stress even in a 'dry' ER fluid if the conductivity or dielectric constant of the additive is still much smaller than that of the dispersed particles.