From "dust" to quality dielectric - the formulation of dielectric clays

As the need for power increased, the electrical industry looked to increase the voltage to reduce losses. Natural rubber was replaced with styrene butadiene rubber (SBR). The SBR was then replaced by butyl rubber; and, finally, butyl rubber was replaced by EPDM and XLPE as the voltages rose from 5 to 15 to 35 to 138 kV. In each of these steps, the rubber compounds required clay initially to enhance mechanical properties, later to improve electrical properties, and finally to give the excellent physical and electrical properties we now know and use. As a result of this evolution, the clay manufacturers responded with purer, more controlled materials to assist in meeting the challenge. This paper discusses that kaolin clay is and how it is converted to electrical grade. It also describes the different compounds with in situ surface compatibilization and the process of quality control and compound formulation.