Surface modification effects in phase change material-infiltrated attapulgite

Attapulgite has nanoporous structure and is an excellent supporting material for the preparation of form stable composite phase change materials (FSCPCMs). However, the effects of surface characteristics of attapulgite on the attapulgite based FSCPCMs were unclear. In this work, the effect of surface modification on the properties of different kinds of attapulgite-based FSCPCMs was investigated. First, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (KH792) was used to modify attapulgite. Then, a series of FSCPCMs were prepared by adsorbing three kinds of phase change materials (PCM) with modified attapulgite (M-ATP). The crystallization and thermal properties of these FSCPCPMs were investigated. The results showed that, the surface modification improves the crystallinity and the latent heat of the FSCPCMs when paraffin or polyethylene glycol are used as the PCM. When the mass fraction of the PCM is 40%, the surface modification increases the latent heat of the paraffin/attapulgite FSCPCM and the polyethylene glycol/attapulgite FSCPCM by 31.5% and 27.8%, respectively. After 800 cooling and heating cycles, the thermal properties of paraffin/M-ATP and polyethylene glycol/M-ATP are still stable. The results were explained by analyzing the interaction between the PCM and the attapulgite. This study provides new ideas to improve the thermal properties of FSCPCMs through surface modification.