Rheodielectric spectroscopy on heterogeneous polymer systems -electrorheological fluids

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

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


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
Issue number9
StatePublished - Sep 1995
Externally publishedYes


  • Electrorheological fluids
  • colloidal suspensions
  • dielectric spectroscopy

ASJC Scopus subject areas

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


Dive into the research topics of 'Rheodielectric spectroscopy on heterogeneous polymer systems -electrorheological fluids'. Together they form a unique fingerprint.

Cite this