Temperature-dependent electrorheological effect and its description with respect to dielectric spectra

Electrorheological fluids consisting of large number and type of electrically polarizable particles have been presented in the literature. Nevertheless, there is a lack of temperature-dependent electrorheological effect analysis, which is their major feature from the application point of view. In this work, aniline oligomers were synthesized and carbonized in order to obtain suitable materials to be used in electrorheological fluids. The silicone oil suspensions were prepared and their temperature-dependent electrorheological performance was investigated in the temperature range between 25 degrees C and 65 degrees C. The electrorheological fluid based on particles with larger size exhibits higher sensitivity to the increase in temperature than the electrorheological fluid based on smaller particles. As an evaluative tool, dielectric spectra of the prepared electrorheological fluids were investigated. It has been shown that the activation energy of the relaxation process is higher for the electrorheological fluid based on larger size particles. The enhanced electrorheological effect at high temperature was ascribed to the shift of dielectric relaxation of the electrorheological fluids to higher frequencies.