BATCHING METHOD AND EFFECTS OF FORMULATION AND MECHANICAL LOADING ON ELECTRICAL CONDUCTIVITY OF NATURAL RUBBER COMPOSITES FILLED WITH MULTI-WALL CARBON NANOTUBE AND CARBON BLACK

Method, formulation and mechanical load variation on electrical conductivity of natural rubber composites filled with multi-wall carbon nanotube and carbon black have been investigated. These nanometer-scale fillers were used due to their good dispersion in the rubber matrix together with their good electrical conductivity. Samples were prepared using five conventional methods involving internal and open-mill mixers, and molding using hot compression machine. Desirable high conductivity and well defined flexure was found best from compounding employing internal mixer which rendered better control in the mixing of chemicals. Two formulations of carbon black were studied: Ketjen Black and Vulcan Black; mixture of the two yielded better conductivity and response to loads than that of Vulcan Black alone, and that the higher the filler content, the better. Conductivity responses to mechanical loading were analyzed at three loading conditions: compression, shear, and combinations of the two. Conductivity of the composite subjected to pure compressive stress and that subjected to loading at different angles similarly behaved nonlinearly; increasing with the angle with respect to normal strain. With respect to shear strain, conductivity increases with decreasing loading angle.