Rheodielectric spectroscopy on heterogeneous polymer systems -electrorheological fluids

P. Placke, R. Richert, E. W. Fischer

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

The technique of rheodielectric spectroscopy is used to investigate the dielectric behaviour of electrorheological fluids (ERF) as a function of external electrical DC-field and/or shear rate. Commercial ERF's consisting of mesoscopic polyurethane particles in a silicone oil matrix were studied. The particles contain a salt which leads to strong dipole moments via the Maxwell-Wagner-Polarization (MWP) if subjected to an external electrical field. In an electrical field the dipoles and, concomittantly, the particles motion become correlated leading to the formation of solid-like structures and significant changes in the viscosity. We demonstrate that dielectric spectroscopy is capable of monitoring the field and shear rate effects in terms of relaxation strength and relaxation time of the MWP. In electrical or shear fields dipole-dipole correlations increase the MWP's relaxation strength, so that we are able to observe structure formation with dielectric spectroscopy, especially the time resolved response of the ERF to changes in the electrical field or the shear rate.

Original languageEnglish (US)
Pages (from-to)848-856
Number of pages9
JournalColloid & Polymer Science
Volume273
Issue number9
DOIs
StatePublished - Sep 1 1995
Externally publishedYes

Keywords

  • Electrorheological fluids
  • colloidal suspensions
  • dielectric spectroscopy

ASJC Scopus subject areas

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

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