Fabrication of multiwalled carbon nanotube-wrapped magnetic carbonyl iron microspheres and their magnetorheology
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Magnetorheological (MR) properties and dispersion stability of magnetic carbonyl iron (CI) microspheres were examined and found to be enhanced by fabricating a dense nest composed of multiwalled carbon nanotubes (MWCNTs) on the surface of CI particles in this study. The coating process is achieved by using 4-aminobenzoic acid as a grafting agent via self-assembly mechanism under sonication in which the MWCNTs were adopted as the coating material because MWCNTs possess similar density with polymer but better magnetic properties due to the iron catalyst originally included within the walls. The coating thickness and morphology of the MWCNTs nest were found to be related with the sonication duration. The influence of the coating layers on the magnetic properties and MR performance (yield stress behavior, shear viscosity) were examined using a vibrating sample magnetometer and rotational rheometer. Sedimentation rates of the fabricated MWCNT/CI suspension and pure CI suspension were also investigated.
KeywordsMagnetorheological fluid Carbonyl iron Multiwalled carbon nanotube Sedimentation
This study was supported by a grant from Inha University (2009) via the GU8 program.
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