Thermo-optic switching properties of paraffin-wax hosting carbon fillers

Abstract Enhancing the thermal- optical properties of phase change materials (PCMs) is the major issue to be addressed when designing thermo optic switch. Paraffin waxes have high thermal energy storage density but low thermal conductivity and, hence, require large surface area. In this paper, we examine the thermal-optical behavior of paraffin wax hosting several concentrations of graphite or graphene, aiming to provide an emerging class of PCMs. Scanning electron microscope SEM were used to characterize the microstructure of the so-formed composite. Heat transfer rates of paraffin wax composites were investigated during heating and cooling phases. The thermal properties were measured using a differential scanning calorimeter DSC). Thermo-optic switching (TOS) based on transmission versus time and temperature under electric heating was analyzed. Results show that both graphite and graphene accelerate melting and solidification heat transfer rate of the paraffin composites. It was observed that, although both graphite and graphene promote decreasing of switching and saturation times, paraffin wax-graphene composite samples cause up to 54% reduction in thermo optical switching time when increasing graphene concentration. These findings have important implication for understanding paraffin-graphene reactivity and surface area modification. These experiments showed a route for paraffin wax hosting carbon fillers as thermo optical sensing materials to be used in TOS device applications.