Poly(methyl methacrylate)-coated carbonyl iron particles and their magnetorheological characteristics

Magnetorheological fluids (MRFs) are types of suspensions that contain magnetic particles and a carrier fluid, and are considered as semi-active smart materials. By tuning the strength of an external magnetic field, like other traditional MRFs, a carbonyl iron (CI)-poly(methyl methacrylate) (PMMA) particle-based MRF can change reversibly from a fluid-like state to a solid-like state within milliseconds. In the research reported, Cl particles were encapsulated with PMMA via emulsion polymerization. After the polymerization, the fabricated CI-PMMA composite particles were dispersed in a suspension medium to prepare MRF. The synthesized CI-PMMA composite particle-based MRF showed a shear stress of 60 kPa at the magnetic field strength of 0.6 T, and a greatly enhanced anti-sedimentation stability. (C) 2010 Society of Chemical Industry