Abstract
Hybrid fillers have been prepared by impregnation of conductive carbon black with different amounts of silicasol, equivalent to 3 % and 7 % silica, respectively. The fillers have been characterized and their effect upon the microwave properties of natural rubber based composites has been also investigated. The results obtained show that, the silica (dielectric) phase is distributed both over the surface and inside the carbon black aggregates (conductive phase). Thus, the interaction between the particles of the conductive filler (building of conductive pathways) is restricted. It has been established that the microwave properties studied are dependent on the ratio between the filler's phases. The composites filled with the hybrid filler comprising the highest amount of silica possess the best total shielding effectiveness and absorptive shielding effectiveness. In all cases absorption is the mechanism prevailing in effectiveness. Thus, the fillers obtained allow an easy control and tailoring of the elastomer based electromagnetic interference shielding materials. The investigations carried out reveal the good potential of the composites studied for finding applications as antennas, automobiles, sensors and military-related applications.