Magnetic Carbonyl Iron Particle Dispersed in Viscoelastic Fluid and Its Magnetorheological Property

Magnetorheological (MR) viscoelastic fluid, consisting of micronsized soft magnetic carbonyl iron (CI) particles and polyisobutylene (PIB)/polybutene (PB) medium matrix instead of commonly used oil for a magnetic carrier, was prepared in this study. The PIB/PB solution is known as a Boger fluid, in which the PIB/PB is similar to MR elastomer matrix as a highly elastic liquid. MR characteristics of the CI dispersed in PIB/PB were measured by both static and dynamic tests using a rotational rheometer with and without an external magnetic field. Static and dynamic yield stress, shear stress, and storage modulus from the rheological measurements were obtained to be increased with applied magnetic field strengths. The system also showed improved sedimentation stability due to the elastic property of PIB/PB viscoelastic fluid.