Preparation and Characterization of Composite Phase Change Materials Based on Lauric-Myristic Acid and Expanded Vermiculite with Carbon Layer

The low thermal conductivity and poor shape stability of phase change materials (PCMs) limit their application in the field of energy-saving buildings. Lauric-myristic acid (LA-MA)/modified expanded vermiculite (MEV) composites as form-stable phase change materials (FS-PCMs) were prepared in this study. To improve their heat transfer properties, expanded vermiculite (EV) was impregnated with sucrose, starch and glucose solutions and then carbonized at a high temperature to attain MEVs, which act as a matrix in the PCMs. LA-MA was adsorbed into the MEVs to obtain the LA-MA/MEV FS-PCMs. Scanning electron microscopy (SEM) shows that both EV and MEV have highly porous structures and can be used as PCMs carriers. The composite PCMs impregnated with starch obtain the best heat transfer properties in comparison with the other two samples. The melting temperature of the composite PCMs is 34.2 degrees C and the melting latent heat value is 141.9 J/g. Thermogravimetric analysis (TGA) shows that the composite PCMs present good thermal stability. Overall, LA-MA/MEV FS-PCMs are promising energy efficient materials that can be used as building materials.