The electrorheological (ER) effect is known as the change in the rheological behaviors of ER fluids under applied electric field E. When an E is imposed, ER fluids show phase transition from a liquid to a solid-like state due to the interactions of polarized particles. This solid-like behavior of particles is due to the increasing viscosity of suspensions. ER materials belong to a family of controllable fluids. ER fluids are dispersions of solid particles in a hydrophobic insulating dispersion medium. These solid particles play a very important role in the ER activity of dispersions. As the dispersed phase, diverse materials such as polymer blends, gels, biodegradable materials, clays, graphene oxide, hybrid nanocomposites, copolymers, ionic liquids, and conducting polymers have been proposed. In the magnetorheological fluids, this control is provided with magnetic field. Various magnetic particles such as carbonyl iron and iron oxides have been suggested as MR material. The combined effect of magnetic and electric field produces intensified rheological changes in the suspensions. This synergic effect is termed as electromagnetorheological effect (EMR). The EMR effect provides a new strategy to control the rheological properties of dispersions.
Part of the book: Smart and Functional Soft Materials