Field-induced structural ordering in electrorheological fluids

P. Placke, V. Edel, L. Reversat, R. Richert, E. W. Fischer

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Structural relaxations of an electrorheological fluid (ERF) due to changes in the applied electrical field strength or shear rate are observed on time scales 1 s<t<40 000 s. Commercial ERFs consisting of mesoscopic polyurethane particles in a silicone oil matrix were studied by three different experimental techniques in order to obtain and compare the characteristic relaxation times. It is demonstrated that dielectric spectroscopy, viscosimetry and light transmission experiments represent the same results concerning the structural relaxation phenomena of ERFs when electrical fields are applied. The tendency of strong induced dipoles to align the particles in the direction of the field increases the effective dipole moment and therefore Δε, the shear viscosity ν and the amount of light transmitted along the field direction in an ITO/glass sandwich cell. The optical experiment is capable of resolving fast processes within the first 1 ms if large electrical fields are applied. The effects of electrophoresis and shearing, which both counteract the field induced structures, are also addressed.

Original languageEnglish (US)
Pages (from-to)1156-1162
Number of pages7
JournalColloid & Polymer Science
Volume273
Issue number12
DOIs
StatePublished - Dec 1 1995

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Keywords

  • Electrorheological fluids
  • colloids
  • light transmission
  • rheodielectric spectroscopy

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Colloid and Surface Chemistry
  • Materials Chemistry

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