Electrical percolation behavior of short-fiber composites: Experimental characterization and modeling

Experimental studies and Monte Carlo simulations have been conducted to investigate the percolation phenomenon in injection-molded short-fiber composites. The electrical resistivity and the percolation thresholds of the short-carbon-fiber-reinforced Nylon 6.6 composites were characterized in the three principal The three-dimensional fiber orientation distribution and fiber length distribution were quantitatively measured by image analysis. As expected, a skin-core morphology was observed in the injection-molded samples. The aligned fiber orientation in the skin does not facilitate the formation of conduction paths, whereas the random fiber orientation in the core enhances the formation of interconnected networks. Voltage-current studies performed on the composite specimens suggest that electron hopping is the probable mechanism of electrical conduction in the matrix polymer present between the fibers. A modified concentric cylindrical model was used to predict the percolation behavior of the molded composite specimens. The agreement between the predictions and the experimental results establishes the effectiveness of the model in simulating the electrical percolation phenomenon in short-fiber composites. (C) 1996 Elsevier Science Limited