Cellular PCM/graphite composites with improved thermal and electrical response

Abstract

This work describes the preparation of cellular graphite/paraffin composites by a facile emulsification-based method. Graphite is readily dispersed in starch aqueous suspension and this readily emulsifies with liquid paraffin above its melting temperature. The resulting emulsion remains stable to allow selective drying of the aqueous suspension, yielding a cellular graphite network consolidated by starch and filled in situ by paraffin. Self organization of the cellular graphite skeleton was easily revealed by volatilization of paraffin. These cellular graphite/paraffin composites show remarkable enhancement of thermal conductivity, in the range 5-8 W m(-1) K-1, and electrical conductivity up to about 6S m(-1). A Taguchi plan was used to analyse the effects of stirring rate, stirring time, starch content and graphite suspension to paraffin volumetric ratio on average cellular cavity size, thermal conductivity and electrical conductivity. This analysis provides trends for further optimization. (C) 2012 Elsevier B.V. All rights reserved.