Stability of Electrical Properties of Carbon Black-Filled Rubbers

摘要

Conducting composites were prepared by melt mixing of ethylene_propylene_diene terpolymer (EPDM) or styrene-butadiene rubber (SBR) and 35 wt % of carbon black (CB). Stability of electrical properties of rubber/ CB composites during cyclic thermal treatment was examined and electrical conductivity was measured in situ. Significant increase of the conductivity was observed already after the first heating_cooling cycle to 85 C for both composites. The increase of conductivity of EPDM/35% CB and SBR/35% CB composites continued when cyclic heating-cooling was extended to 105 C and 125 C. This effect can be explained by reorganization of conducting paths during the thermal treatment to the more conducting network. EPDM/35% CB and SBR/35% CB composites exhibited very good stability of electrical conductivity during storage at ambient conditions. The electrical conductivity of fresh prepared EPDM/35% CB composite was 1.7×10~(-2)S cm~(-1)and slightly lower conductivity value 1.1×10~(-2)S cm~(-1)was measured for SBR/35% CB. The values did not significantly change after three years storage.