the effects of γ-ray irradiation dose on the electrical resistance and ptc temperature of polyethylene/carbon composite

polymer-graphite powder composite behaves as a low-conductive material which can be used as an automatic fuse for adhesive connector in electrical circuits. the conductivity of this composite, below its transition temperature, tt, depends on concentration of carbon powder, slowly decreases as the temperature increases. meanwhile, the electrical resistivity of this material in transition temperature region severely increases. the amount of tt was found to be ~148oc for polyethylene-carbon independent of its concentration. in this work, the rate of change in electrical resistance of thiscomposite in terms of temperature, carbon concentration and γ-ray irradiation dose has been investigated. also, the values of tt and the peak resistance temperature, tp of samples in each case were determined. the results show that both values of tt and tp decrease with increasing of irradiation dose. it has been found that the concentration of carbon powder has no significant effect on the transition temperatures of samples.