Electrorheological Properties of Lead Titanate and Zeolite Silicone Oil Suspensions

Abstract

The purpose of this research has been to prepare and accurately evaluate the dielectric and rheological properties of lead titanate/silicone oil and zeolite/silicone oil suspensions. The dielectric characteristics and rheological changes occurring with the application of electric fields to the suspensions were compared and the lead titanate suspensions were examined for potential use as electrorheological (ER) fluids. A dielectric spectrometer was utilized to quantify the particle/fluid dielectric mismatch of the lead titanate suspensions and the particle/fluid conductivity mismatch of the zeolite suspensions. The rheological properties were examined by conducting a series of systematic analyses without an electric field and then subsequently with the application of dc and ac fields of various frequencies. Optical microscopy of the suspensions without and with an applied electric field has been employed to determine the particle movement and structure within the suspensions. Observations of the lead titanate particles in suspension under an applied electric field elicited the electrophoretic nature of the particles, which moved towards the electrodes instead of forming chains of particles bridging the electrodes. The lead titanate suspensions exhibited either a very small positive ER effect or in some cases a slight negative ER effect, which involves a reduction in the yield stress with applied electric field. This leads us to conclude that the lead titanate/silicone oil suspensions examined in this study are ineffective ER fluid materials. The zeolite/silicone oil suspensions exhibited a positive ER effect.