Investigating the Dielectric Properties of Carbon Black-Epoxy Composites

Abstract

ABSTRACT After reviewing some theoretical facts and early theories, this work presents a study of the dielectric properties of carbon black (Raven 7000) dispersions in an insulating epoxy matrix (diglycidylic ether of bisphe-nol F) in the frequency range 1kHz to 15MHz. In an earlier study,[ 1 El Bouazzaoui , S. ; Achour , M. E. ; Brosseau , C. Microwave effective permittivity of carbon black filled polymers: Comparison of mixing law and effective medium equation predictions . J. Appl. Phys. 2011 , 770 ( 7 ), 074105(1)-074105(9) . [Google Scholar] ] it was shown that different mixture laws (Maxwell Garnett, Bruggeman, Lichtenecker, and Rother) correctly account for the experimental values of the effective complex permittivity at low particle concentrations. However, they fail to represent the data at the larger concentrations studied. Here, the two-exponent phenomenological percolation equation is used to characterize the permittivity of these composites. It is discussed whether or not this phenomenological equation is capable of representing the effective permittivity versus carbon black volume fraction.