The role of particle conductivity in electrorheology of suspensions of variously protonated polyaniline

Abstract

Abstract. Electrorheological behaviour of silicone oil suspensions of particles of polyaniline protonated to various doping level with orthophosphoric and tetrafluoroboric acids has been studied. The dynamic yield stress obtained by extrapolation of shear stress to zero shear rate using Herschel-Bulkley equation was used as a criterion of the ER efficiency. At a same molar concentration of doping acids, various protonation effects appeared and the dependences of the yield stress on the acid concentration differed. The comparison of the yield stresses with dielectric characteristics calculated from the Havriliak-Negami equation revealed that the particle conductivity unlike particle permittivity especially at higher protonation degree is dominant in polarization process. Consequently, particle conductivity or dielectric relaxation time proved to be the parameters providing the common dependences of the yield stress regardless of the way of polarization.

Carbonization of aniline oligomers to electrically polarizable particles and their use in electrorheology

“…Among them polyaniline (PANI) [8,9] and polypyrrole [10] are of special interest. Polyaniline, as a material for electrorheology, has been reported in many scientific papers due to its easy and inexpensive synthesis [5,8,[11][12][13][14][15][16][17][18]. Moreover, aniline-like oligomers with tuneable conductivities prepared by different reaction conditions or reaction substances have been introduced [19][20][21].…”