PERCOLATION CONCEPT - POLYMER-FILLER GEL FORMATION, ELECTRICAL-CONDUCTIVITY AND DYNAMIC ELECTRICAL-PROPERTIES OF CARBON-BLACK-FILLED RUBBERS

This paper reports results on comparison of polymer-filler gel formati on measurements and electrical properties of carbon black filled styre ne butadiene rubber (SBR) composites. Electrical conductivity (sigma) of compounds with different filler concentration has been measured, an d dielectric constant (epsilon'), dielectric loss (epsilon '') and dis sipation factor (tan delta) have been investigated at frequency range from 1 kHz to 13 MHz. It has been found that these systems follow perc olation type model. Different electrical percolation thresholds of the composites have been found for different types of carbon black. Carbo n blacks with the highest specific surface area reach the percolation threshold with the least fraction of carbon black loading. The electri cal percolation threshold was found to be in a very good agreement wit h the filler concentration which is necessary for the coherent rubber- filler gel formation.