Abstract: In this paper the influence of the-voltage on the resistance of polyethylene-carbon black composites has been studied, and thus the resistance-temperature behavior has been examined more accurately. The relationship between resistance and temperature could be expressed by an exponential formula: R = M. exp(N(t + 80)/(110-t)), which is coincident with temperature up to 10-30℃ below the M.P. of polyethylene depending on the carbon black content.The relationship between the expansion coefficient and temperature was compared with the PTC phenomenon of the materials. High expansion coefficient of the matrix is essential for the conductive composites to possess PTC effect.

Key words: carbon black, polyethylene conductive composite