Carbon Black for Electrically Conductive Polymer Applications

Abstract

Carbon black is incorporated in polymers for permanent electrostatic charge protection, explosion\rprevention, and polymer applications that require electrical resistivities below 106 O cm. At the\rcritical volume fraction of the carbon black grade, the carbon black-polymer compound percolates\rfrom an electrically insulating to a conducting domain. The capability of a carbon black material to\rimpart electrical conductivity to a polymer compound depends on its ability to establish and\rmaintain in the insulating polymer matrix a conductive network in which the electronic charge\rcarriers move mainly by a tunneling mechanism. Conductive carbon black fillers impart electrical\rconductivity to polymers at lower critical volume fractions than conventional carbon blacks and\rhence influence to a lower degree the mechanical properties of the resulting conducting polymer\rcompound. The key property of this family of special carbon black grades is a carbon black high\rstructure, i.e., a high void volume. High-structured carbon black materials are preferred fillers to\rmake polymers conductive as they allow high polymer concentrations to be maintained while\restablishing the conductive network. Besides the carbon black properties, also the polymer properties\rand the processing of the carbon black-filled polymer compound influence the critical volume\rfraction and insulator-conductor transition. Statistical, thermodynamic, and structure-oriented percolation\rmodels are the best applicable to describe at a theoretical scientific level the formation of the\rconductive carbon black network in the polymer matrix.