Stearic acid hybridizing kaolinite as shape-stabilized phase change material for thermal energy storage

To explore the effect of particle size distributions of supports on thermal performances of phase change materials (PCMs), shape-stabilized composites were prepared by using stearic acid (SA) to hybridize size-different kaolinite (Kaol). The samples were characterized using SEM, XRD, FTIR, BET and DSC techniques. The results indicated that superior thermal capacity was ascribed to higher loading capacity and crystallinity of SA, which was closely related to the layout state of Kaol within the composites. Enhanced thermal conductivity could be achieved with the increasing crystallinity, the descending interfacial thermal resistance and efficient heat conductive network. The establishment of heat transfer network depended largely on the mutual proportion between small-sized and large-sized particles in supports. The tiny particles were inferred to act as junctions to bridge the separately dispersed plates, which was contributed to the continuous heat conducting pathways. The results suggested that particle size distributions of Kaol could exert a great influence on thermal performances of composites. Furthermore, Kaol could obviously uplift the thermal stability of composites, and the thermal cycling test has validated its excellent thermal reliability. We believe that this study will play an enlightening role in the design and fabrication of highly-efficient shape-stabilized PCMs for solar energy storage.