Systematic investigation on shape stability of high-efficiency SEBS/paraffin form-stable phase change materials

In this work, form-stable phase change materials (FSPCMs) comprising paraffin as latent heat storage material and styrene-b-(ethylene-co-butylene)-b-styrene triblock copolymer (SEBS) as supporting material were prepared, and their shape stability was studied systematically by rheological analysis for a deep understanding of shape stability mechanism. The mass percentage of paraffin can reach 90 wt% without any obvious leakage of paraffin above its melting point, suggesting excellent energy storage capacity. The results of rheological measurement reveal that the shape stability of these composites derives from the formation of SEBS–paraffin reversible physical gel, which can prevent the free flowage of melted paraffin, while the failure to keep their apparent shapes stable at a further higher temperature may be ascribed to hard gel–soft gel and gel–fluid transitions. In addition, thermal properties and thermal stability of the composites were also investigated. This study proposed a universal method to detect the variation of materials with temperature and deeply understand the physical mechanism of shape stability, which not only accelerates the pace for practical application of existing FSPCMs, but also provides foundational insight for the design of new FSPCMs. Considering the proposed analysis method is applicable for most FSPCMs, this work may build up bridges for both comprehensive academic research and industrial application of FSPCMs.