Abstract
This paper discusses relationships between electrical properties of Ni particle dispersed high-density polyethylene (HDPE) composites and Ni content and weight-average molecular weight (Mw) of HDPE. We also investigate conductive path structures formed by Ni particles based on results from SEM observation and percolation model analysis. The ρL (resistivity at room temperature) decreased with increasing Ni content, and these behaviors consisted with percolation behavior. Percolation threshold decreased with decreasing Mw of HDPE. Crystallinity of HDPE increased with decreasing Mw of HDPE. It was expected that Ni particles are concentrated spatially in amorphous region of HDPE. Therefore, percolation threshold decreased with increasing crystallinity of HDPE due to decrease of Mw of HDPE. The temperature of positive temperature coefficient (PTC) effect (inflection point of PTC curve) decreased with decreasing Ni content. It is considered that lower Ni content leads to disconnection of conductive path because conductive path becomes much less with decreasing Ni content. When Ni content is the same, the temperature of PTC effect rose with decreasing Mw of HDPE. This was due to increase of crystallinity of HDPE by decreasing Mw of HDPE.
