Investigation on effect of carbon black and polymer matrix on conductive polymer composites with positive temperature coefficient

It was found that the base resistivity of conductive polymer composite and its behavior of positive temperature coefficient (PTC) versus temperature depend on the filler carbon black. Carbon blacks with large particle size, small surface area, and small amount of aggregate structure lead to high base resistivity and large amplitude of PTC (defined as the ratio of maximum resistivity to the resistivity at room temperature). While, carbon blacks with small particle size, large surface area, and large amount of aggregate structure lead to low base resistivity and low PTC amplitude. In this paper, the base resistivity of polymer composite filled with bimodal carbon blacks (with both large and small carbon black particles) is reported. Effect of carbon black filler on crystallinity of polymer matrix will also be determined. The effect of polymer matrix on base resistivity and PTC amplitude will be demonstrated.