Oleophobic modification of clay minerals to improve encapsulation ratios of shape-stabilized phase change materials: A universal method

Abstract

Liquid-solid phase change materials (PCMs) show reversible storage and release of latent heat, which has attracted extensive interests in applications for thermal energy storage. However, stubborn leakage issue may cause corrosion and extra thermal resistance. The non-wettability of melted paraffin on the oleophobic surface of diatomite has been reported by authors earlier, and the result showed that the encapsulation ratio (84.5%) of diatomite@paraffin shape-stabilized PCM greatly increased. Here, in order to prove this method equally applicable to other PCMs and porous natural clay minerals, diatomite and sepiolite were oleophobically modified to encapsulate melted stearic acid and paraffin, to form shape-stabilized PCMs. The results showed that the encapsulation ratios of 67.8% and 56.6% for diatomite@stearic acid and sepiolite@paraffin were higher than that reported in the references (28.9% and 36.8%). In addition, the encapsulation ratios of diatomite-based shape-stabilized PCMs can be also increased using different PCMs, such as n-octadecane and polyethylene glycol via the same approach. Therefore, this is a universal method for improving encapsulation ratios of shape-stabilized PCMs.