Frequency and temperature dependence of ac electrical properties of graphitized carbon‐black filled rubbers

The a.c. electrical properties of graphitized carbon-black filled rubbers were investigated in the temperature range 25-85°C and in the frequency range 10-10 6 Hz. The volume fraction of the filler varied from 15 to 60%. The a.c. impedance was found to decrease dramatically with increasing filler content for volume fractions higher than 30%. A relaxation transition with an activation energy of 26.4-50 kJ/mol was observed only in the samples containing 45% and 60% of the fillers.