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The dielectric characteristics of various modified montmorillonites suspensions in polydimethylsiloxane were investigated. Such materials are promising candidates as electrorheological fluids. The effect of small water content and temperature change in the dielectric spectra of suspensions was studied. The electrical conductivity of suspensions rises with filler concentration. Conductivity also increases with frequency for all samples by 5-6 orders of magnitude. The frequency dependence of permittivity changes significantly with temperature and strongly depends on the type of modifier. The positions of relaxation transitions peaks observed in dielectric loss curves substantially depend on the type of filler and water content. Dielectric loss peaks shift to higher frequencies with temperature. Relaxation mechanism is related to filler and described by capacitor model. Based on X-ray data a model of relaxation transitions is proposed. Also, the activation energy of dielectric relaxation is estimated. The activation energy is independent of filler concentration but is determined by the structural features of fillers in polymer medium. The prospects of dielectric spectroscopy for analyzing the layered nanosilicates structure in polymer solution are demonstrated. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46614.

Electrorheological fluids based on polydimethylsiloxane filled with halloysite nanotubes were studied. The filler structure was characterized by TEM, SEM, and X-ray diffraction. When an electric field is applied to suspensions, their rheological behavior changes-the contribution of the elastic component becomes significant and samples behave like a solid body. The effect of the electric field and filler concentration on the electrorheological behavior was investigated. The influence of water content on the filler structure, as well as on electrorheological and electrophysical properties of suspensions, was considered. Electrorheological fluids filled by halloysite with small water content exhibit slightly higher rheological characteristics under an electric field than dried ones. This study shows the prospects of using halloysite nanotubes as a dispersed phase for electrorheological fluids.