Synergistic effects of carbon fillers in electrically conductive nylon 6,6 and polycarbonate based resins

The electrical conductivity of polymeric materials can be increased by the addition of carbon fillers, such as carbon fibers, carbon black, and synthetic, graphite. The resulting composites could be used in applications such as electromagnetic and radio frequency interference shielding and electrostatic dissipation. A significant amount of work has been conducted varying the amount of single conductive fillers in a composite material. In contrast, very limited work has been conducted concerning the effect of combinations of various types of conductive fillers. In this study, three different carbon fillers were used: carbon black, synthetic graphite particles, and pitch based carbon fiber. Two different polymers were used: nylon 6,6 and polycarbonate. The goal of this project was to determine the effect of each filler and combinations of different fillers on the electrical conductivity of conductive resins; A 2(3) factorial design was analyzed to determine the effects of the three different carbon fillers in nylon 6,6 and polycarbonate. The results showed that carbon black caused the largest increase in composite electrical conductivity. The factorial design analysis also showed that combinations of different carbon fillers do have a positive synergistic effect, thereby increasing the composite electrical conductivity.