The Conductivity Change in Polyethylene During γ-Irradiation

The effect of Co60 γ-irradiation on the direct current conductivity σ of polyethylene has been determined up to an intensity I of 4000 roentgens per hour at room temperature. The equation σ/σ00=1+(I/I0)34describes the data where σ00 is the conductivity without radiation and is the order of 10−18 (ohm cm)−1 and I0 is 20 roentgen/hr. Measurements at liquid nitrogen temperatures give a factor of 20 decrease in the normal conductivity and a factor of 25 decrease in the radiation induced conductivity below their respective room temperature values. The temperature data serves to suggest an ionic mechanism for electrical conduction in polyethylene as opposed to an electronic mechanism. In fact, the ion contributing most to the conduction in the polyethylene may well be the proton.