Preparation and characterization of capric-palmitic acids eutectics/silica xerogel/exfoliated graphite nanoplatelets form-stable phase change materials

Capric-palmitic acids eutectics (CA-PA)/silica xerogel and CA-PA/silica xerogel/exfoliated graphite nanoplatelets (xGnP) form-stable phase change materials (PCMs) were prepared via a facile sol-gel method. Characterization of the prepared form-stable PCMs revealed that after incorporating xGnP into the hydrophilic silica xerogel, the loading of the hydrophobic CA-PA in the form-stable PCMs was effectively improved while the thermal conductivity of the form-stable PCMs was significantly enhanced at the same time. The loading of CA-PA in the CA–PA/silica form-stable PCMs with good form-stability could attain 75 wt%, and was further increased to 85 wt% in the CA–PA/silica/xGnP form-stable PCM containing 6 wt% xGnP. The latent heat of the CA–PA/silica and the CA–PA/silica/xGnP form-stable PCMs could attain 103.4 and 123.1 J/g, respectively, and possessed good long-term thermal reliability. The CA–PA/silica form-stable PCM exhibited an exceedingly low thermal conductivity of 0.17 W/mK and a very slow speed of heat storage and releasing, which made it a promising candidate for thermal regulating material. On the other hand, the thermal conductivity of the CA–PA/silica/xGnP form-stable PCMs was greatly enhanced by xGnP. The thermal conductivity of the CA–PA/silica/xGnP form-stable PCM with 85 wt% CA-PA and 6 wt% xGnP could attain 0.70 W/mK, which was 218% higher than that of CA-PA. The high thermal conductivity also resulted in a higher speed of heat storage and releasing, which was in favor of its application as latent heat storage material for building-comfort control.