Form-stable and thermally induced flexible composite phase change material for thermal energy storage and thermal management applications

High latent heat of phase change materials (PCM) has made them as one of the most potential materials in many advanced applications. However, application of PCM is limited by the issues of low thermal conductivity, leakage and strong rigidity. In this work, a novel form-stable and thermally induced flexible composite PCM inspired by shape memory polymers was successfully prepared. Here, paraffin (PA) with large latent heat was employed as PCM, olefin block copolymer (OBC) performed as the supporting material and expanded graphite (EG) was the additives for thermal conductivity enhancement. The structure and properties of prepared composites were characterized by FT-IR, XRD, SEM, DSC and TG. There was a good physicochemical compatibility among the components of the PA/OBC/EG composites. Two well-distinguished melting points could be observed and the obtained composites presented a good thermal stability during the working temperature range. Further, the composites also demonstrated excellent form-stable property according to the leakage test. There was no obvious PA leakage when the mass fraction of OBC in PA/OBC blends was 20% and EG had a positive effect on the leakage rate. Simultaneously, the good softness and flexibility achieved by triggering the phase transition of PA could lead to many deformation modes such as bend and compression, which were beneficial for thermal contact resistance decrease and installation improvement. Finally, the heat transfer characteristics were investigated experimentally. The heating and cooling processes were mainly affected by three factors, namely, thermal conduction, natural convection and absorption of latent heat. With EG impregnated in the composites, the heating and cooling rate could be amplified and thus improved the overall thermal performance. The results presented in this work indicate that the prepared composite PCM possesses a potential application for thermal energy storage and thermal management.