Preparation And Thermophysical Properties Of Graphene-based Composite Phase Change Materials

Latent heat storage technology is an effective thermal energy storage technology,which has potential application prospects in building energy saving,temperature-regulated clothing,waste heat recovery,solar thermal utilization and multi-configuration integration.Carbon-based stereotyped composite phase change materials can better solve the inherent defects of solid-liquid phase change material,such as easy leakage and low thermal conductivity.However,the introduction of carbon-based carrier changes the phase transition range and crystalline microenvironment of phase change molecules,and its influence on the thermophysical properties of composite phase change materials is still unclear.To this end,a series of graphene-based composite phase change materials were prepared by low-temperature hydrothermal self-assembly method using different modified graphenes as carrier.The structure,morphology and thermophysical properties of composite phase change materials were studied,and the effect of graphene-based carrier on the thermophysical properties of composite phase change materials was explored.Using paraffin（PF）and n-hexadecyl alcohol（HD）as phase change materials,graphene oxide（GO）and carboxylated graphene oxide（GO-COOH）as confinement carrier,four stereotyped composite phase change materials were prepared by hydrothermal self-assembly method.The structure,morphology and thermophysical properties of composite phase change materials were studied by various means.The results show that:There is only physical interaction between carrier and phase change material among the four composite phase change materials,and the compatibility is good,but the confinement effect changes the crystal structure of HD.The composite phase change materials have high loading rate,large latent heat,good thermal stability,and its thermal conductivity is significantly higher than that of pure substances,which have potential application prospect.Using Stearic acid（SA）as phase change material and modified graphene oxide as confinement carrier,five SA/graphene-based composite phase change materials were prepared by hydrothermal self-assembly method.The shape stability,structural characteristics and thermophysical properties of composite phase change materials were explored.The results show that the five composite phase change materials have good shape stability,the SA content ranges is 94.93%～96.11%,and the latent heat of phase change range is 141.63 J·g^-1～183.53J·g^-1.Under the inducement of the lamellar structure of carrier and host-guest non-covalent interaction,SA with the tendency of lamellar structure interacts with carrier to form a“sandwich”stacking structure.The introduction of graphene-based carrier increased the decomposition temperature of SA,especially due to the interface between carrier and phase change material,the phase transition temperature of five composite phase change materials increased between 29.99℃～32.47℃.Non-isothermal crystallization kinetics studies showed that AG-COOH reduced the crystallization rate of SA and increased the semi-crystallization time.Meanwhile,r AG and r AG-TEPA increased the nucleation sites of SA and promoted the crystallization of SA.The research results are expected to provide basic data for in-depth understanding of the influence of interfacial interaction on the thermophysical properties of composite phase change materials.