AC electrical properties of titanate-linkcoupled carbon black filled polypropylene composites

In this paper, Carbon black was activated using titanate-type coupling agent, and then filled into polypropylene to prepare conductive composites, whose alternating current (AC) electrical properties, including impendence Z, phase angel theta, dielectric constant epsilon and dissipation factor tg delta that is a function of frequency and carbon black concentration were investigated by AC impedance spectroscopy. The percolation threshold of 5wt% carbon black concentration was obtained from the experimental result of volume resistivity for the conductive composites. It was found that the variation of AC electrical properties, which is a function of frequency, was dramatic and dependent on the filler concentration. It was also found that dependence of the real and the imaginary parts of impendence on frequency decreased with the increased concentration of carbon black, while the phase angle, dielectric constant and dissipation factor increased. The AC electrical properties were given based on the conductive network model and the corresponding equivalent circuit were concluded.