Magnetorheological characteristics of nanoparticle-added carbonyl iron system

Magnetorheological (MR) fluid, suspension of magnetic carbonyl iron (CI) and magnetic additives in mineral oil, were prepared. The novel core–shell structured additives, comprising monodisperse polystyrene (PS) spheres as cores and magnetite as shells, were fabricated by surfactant-free emulsion polymerization. This MR fluid with bimodal particles was suspended in mineral oil and their MR characteristics were examined via a rotational rheometer in a parallel plate geometry equipped with a magnetic field supplier. MR properties of the bimodal MR fluid with magnetic additive exhibit similar magnetic and MR properties compared to MR fluid consisting of pristine CI, but with much improved dispersion stability.