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 /spl deg/C. The composites show a dielectric relaxation, which obeys a Cole-Cole circular arc law. The strength of relaxation, /spl delta/ /spl epsi/, and the parameter /spl beta/, 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 /spl deg/C is due to a scission of conducting paths caused by the thermal expansion of the resin, because of the increase of /spl delta/ /spl epsi/ above 70 /spl deg/C. The decrement of /spl beta/ indicates that the scission makes the distribution of relaxation broader. In the temperature region below 70 /spl deg/C, /spl delta/, /spl epsi/ decreases with heating. It is concluded that branches likely combine to conducting paths, bringing about a mild increase in resistivity with increasing temperature.<
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