Temperature dependence of resistivity and dielectric property of furnace carbon black-polyethylene composite

The temperature dependence of the resistivity and dielectric properties of carbon black-polyethylene composites was measured in the temperature range from room temperature to 95 °C. The composites show a dielectric relaxation, which obeys a Cole-Cole circular arc law. The strength of relaxation, δ ε, and the parameter β, a measure of the distribution of relaxation time, were estimated from the Cole-Cole plot. It is suggested that the rapid increase of resistivity observed about 70 °C is due to a scission of conducting paths caused by the thermal expansion of the resin, because of the increase of δ ε above 70 °C. The decrement of β indicates that the scission makes the distribution of relaxation broader. In the temperature region below 70 °C, δ, ε decreases with heating. It is concluded that branches likely combine to conducting paths, bringing about a mild increase in resistivity with increasing temperature