Fabrication and magnetorheological property of core/shell structured magnetic composite particle encapsulated with cross-linked poly(methyl methacrylate)

Abstract

Hybrid magnetic particle of carbonyl iron (CI) microsphere and cross-linked poly(methyl methacrylate) (PMMA) with core/shell structure was prepared to be adopted as a dispersed particle for a magnetorheological (MR) fluid. The magnetic hybrid composite microsphere was synthesized via a dispersion polymerization in the presence of CI, in which the PMMA was cross-linked using ethylene glycol dimethacrylate during polymerization for its enhancement in both chemical resistance and surface hardness. Magnetic property and morphology of the produced hybrid particles were examined via a vibrating sample magnetometer and scanning electron microscopy, respectively. The hybrid magnetic microsphere based MR fluids were then investigated under different external magnetic field strengths via a rotational rheometer. Their flow behaviors showing typical MR characteristics at a steady shear mode along with shear viscosity were examined under applied external magnetic field strength. © 2009 Elsevier B.V. All rights reserved.