Influence of filler structure on microhardness of carbon black-polymer composites

The microhardness, H, of carbon black-polycarbonate and carbon black-low-de nsity polyethylene composites was investigated. Two types of microadditives with different average particle sizes were employed. It has been shown tha t the morphology of the polymeric matrix conspicuously influences the hardn ess dependence of the composites with volume concentration of filler, phi. The microhardness of the carbon black-polycarbonate composites shows a step like behavior with respect to carbon black content, while the H value of th e carbon black-low-density polyethylene composite linearly increases with i ncreasing phi. The influence of filler structure on the microhardness of th e carbon black-polymer composites is also discussed. Results favor the conc ept that a smaller carbon black particle size (smaller aggregate diameters and interaggregate distances) enhances the microhardness of the composites. (C) 2000 John Wiley & Sons, Inc.