Novel Positive Temperature Coefficient Effect of Electrical Resistivity in Ni Particles Filled Two Semi-Crystalline...

A novel positive temperature coefficient (PTC) effect nanocomposite by employing both of polyvinylidene fluoride (PP) and polypropylene (PVDF) intermixture in 1-1 volume ratio as host materials and Ni nanoparticles as conductive filler was prepared via a simple hot compaction method. This study focused on the effect of Ni content on percolation threshold and temperature dependence of direct current (DC) resistivity, as well as frequency dependence of alternating current (AC) resistivity of nanocomposites. This kind of material showed a very small percolation threshold value (about 6.0 vol% of Ni) and a novel strong PTC effect of electrical resistivity between temperatures ranging 150-167 °C, which coincided with the both melting temperatures of PP and PVDF. Close to the percolation threshold, abnormal electrical behavior was observed and interpreted based on the tunnel conductivity between Ni clusters. The curves of the AC resistivity versus the frequency, at different loadings of Ni and at different temperatures, offered a further image of the arrangement of conducting clusters within the host.