dc electrical conduction in carbon black filled <i>c</i> <i>i</i> <i>s</i>-polybutadiene

Abstract

dc electrical conductivity measurements on carbon black filled cis-polybutadiene are reported. A temperature reversible peak is found in the resistance (defined as V/I) versus temperature curves which separates regions of positive and negative temperature coefficients. The temperature of the peak depends critically upon the type of black and the voltage used for the measurement. The data have been analyzed in terms of two contributions to the conductivity: (i) an intrinsic Ohmic process, described by an activation energy DE = 0.6 eV, and identified with ionic conduction in the rubber matrix, and (ii) a non-Ohmic mechanism which dominates at high filler loadings, high fields, and low temperatures. This process obeys an expression of the form I = AVeBV. NMR measurements on the samples show that there is no gross irreversible morphological rearrangement over the temperature range studied.