Electrical Conductivity of Carbon Black-Reinforced Elastomers

Electrical conductivity of carbon black‐reinforced elastomers at fixed loading is a function of the particle size and aggregation habit of the carbon black, its intrinsic conductivity, and the ability of the black to adsorb certain ionic impurities. These factors vary greatly in their relative importance, depending on the filler concentration. The mechanism of conduction is primarily one of carbon black chain formation. Experimental evidence suggests the existence of a small number of highly conductive paths consisting of rather large black aggregates in contact in addition to a fine network of carbon black chains formed by otherwise well‐dispersed black. Electrical conductivity data supporting the above conclusions are presented for nine carbon blacks in GR‐S, natural, and butyl rubbers.