Abstract
In recent years, special grades of electroconductive carbon black have been developed to overcome the usage of large amounts of filler in the preparation of composites with desired electrical properties. Characteristic features of the novel carbon black are its superhigh specific surface area and structure, which are many times higher than those of conventional electroconductive carbon black. The present article reports on natural-rubber-based composites, filled with carbon black of superhigh specific surface area and structure. New results concerning the influence of change in the filler concentration, applied pressure, and temperature on the volume resisitivity of the composites are presented and discussed. It has been found that the new filler lowers the percolation threshold greatly and ensures very high electroconductivity at low content. The influence of applied pressure on the volume resistivity depends on whether the amount of filler used is sufficient to reach or pass the percolation threshold: when the percolation threshold is not reached, the volume resistivity increases with increasing pressure; after reaching the percolation threshold, the volume resistivity decreases with increasing pressure. With increase in temperature, the volume resistivity of the examined composites decreases. With increase in the degree of filling, the examined hysteresis decreases too. The results obtained for the new conductive rubber composites may be considered as a novel contribution in the field of polymer materials research.