Electrical resistivity of sheet-type heaters with nanocarbon fillers

Abstract

Sheet-type heaters were prepared using polyimide as a matrix with a mixture of two types of vapor-grown nanocarbon fillers, VGCF and cup-stacked carbon nanotubes (CSNT), and their electrical resistivity, thermal expansion and filler dispersion properties were evaluated. By using the heat resistant polymer, polyimide, it was expected that the positive temperature coefficient (PTC) effects appear at higher temperatures. The results showed that the nanocarbons were dispersed homogeneously and that the temperature dependence of the electrical resistivity could be controlled by the addition of two types of nanocarbon fillers. The optimum PTC properties were observed for the samples with the mixture of VGCF and CSNT at 30 wt % of total nanocarbons.