Magnetorheological response of soft-magnetic carbonyl iron microbeads dispersed in a poly(ethylene oxide) solution

A magnetorheological (MR) fluid is a smart magnetic particle suspension with the ability of being transformed from a liquid-like to a solid-like state under the stimulus of a magnetic field. However, in the absence of the magnetic field, dispersed magnetic particles of high density are apt to settle, resulting in poor dispersion stability. In this study, we introduced an aqueous poly(ethylene oxide) (PEO) solution with controlled shear viscosity as a medium fluid for a carbonyl-iron-based MR fluid. Its rheological and dispersion properties were studied by varying the molecular weight of the PEO. Field dependences of its MR properties were observed by using a rotational rheometer with an attached MR device.