Highly conducting core–shell phase change materials for thermal regulation

Abstract

A core–shell model has been derived for microstructural design of PCM-based composites with optimized 3-dimensional organization of a conducting phase, and a novel method was developed to process self-assembled core–shell composites for thermal regulation or heat storage. The method was based on emulsification of graphite suspensions in melted paraffin yielding a core–shell microstructure based on self-organisation of graphite platelets with preferential orientation; this allows remarkable enhancement of thermal conductivity, which increases by at least one order of magnitude for 5 vol% graphite addition. The microstructure of the graphite shell remains stable upon repeated cycling above and below the melting temperature of the paraffin, and shape stabilization is also retained, even without external encapsulation. One confirm that the levels of thermal conductivity of these phase change materials is sufficient for latent heat discharge from relatively large spherical samples to surrounding air.