Rheological properties and stabilization of magnetorheological fluids in a water-in-oil emulsion

Jong Hyeok Park, Byung Doo Chin, O. Ok Park

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Abstract

The rheological properties and dispersion stability of magnetorheological (MR) fluids consisting of hydrophilic treated carbonyl iron particles dispersed in a water-in-oil emulsion were studied for the first time by the use of a stress-controlled rheometer and sedimentation test. In order to improve the stability of the MR fluids, carbonyl iron magnetic particles were chemisorbed by Tween 80 and a water-in-oil emulsion was employed as a continuous phase for MR fluids. Attraction between hydrophilic-treated carbonyl iron and water emulsion in continuous phase plays a critical role in greatly improving stability of dense carbonyl iron particles against sedimentation without restricting rheological properties. On application of magnetic fields, the suspensions show a striking increase in viscosity. Since constant stress is generated within the limit of zero shear rate, the plateau in the flow curve corresponds to the Bingham yield stress. Under a low external magnetic field, the yield stress varied as B3/2, indicating that local magnetization saturation occurs between the neighboring magnetized particles. The yield stress has an approximately linear relation to the particle volume fraction.

Original languageEnglish
Pages (from-to)349-354
Number of pages6
JournalJournal of Colloid and Interface Science
Volume240
Issue number1
DOIs
Publication statusPublished - 2001 Aug 1

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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