Effect of ingredients on the electrical conductivity of styrene butadiene rubber

The effect of different ingredients, which are usually added during the preparation of rubber mixtures, on the electrical conductivity σ of styrene‐butadiene rubber (SBR‐1502) has been studied. It was found that processing oil (as softener) showed a marked increase in σ with respect to the pure sample. Stearic acid (as antioxidant), however, did not show a considerable effect on σ. The addition of constant concentration of 50 phr from different types of carbon black (filler) namely, ISAF, HAF, FEF and SRF to the rubber matrix resulted in different values of the initial conductivity of the vulcanized samples. The conduction mechanism through carbon black‐loaded rubber vulcanizates has been discussed and rough estimation of the separation distance between carbon black particles (or aggregates) suggested. The carbon black‐loaded rubber vulcanizates showed a reasonable stability and reproducibility of σ after pre‐thermal‐oxidative ageing at 365 K for 30 days.