Synthesis and Thermal Properties of Myristic Acid/Nano-TiO₂/Carbon Additives Composite Phase Change Materials

A novel composite phase change material, myristic acid (MA)/nano-titanium dioxide (nano-TiO₂)/carbon additives, was synthesized via a melt blending method, in which MA serves as phase change material, nano-TiO₂ acts as support material, and carbon additives are used as thermally conductive enhancer. A series of leakage tests have shown that MA/nano-TiO₂ can maintain shape stability during the phase transition when the content of MA in MA/nano-TiO₂ does not exceed 50 %. The FT-IR and XRD results demonstrated that there is no chemical reaction among the various components of the MA/nano-TiO₂/carbon additive. When the content of MA is 50 %, the melting temperature of MA/nano-TiO₂/carbon additives is about 54 °C and the melting enthalpy is about 80 J·g⁻¹. When the content of all three carbon additives, multiwall carbon nanotubes, graphene, and expanded graphite, is 2.5 %, the corresponding thermal conductivity of MA/nano-TiO₂/carbon additives is 0.532 W/(m·K), 1.128 W/(m·K), and 1.382 W/(m·K), respectively. The thermal conductivity of these three types of MA/nano-TiO₂/additives is 1.23, 2.62, and 3.21 times that of MA/TiO₂, respectively. Moreover, the decomposition temperature of these three types MA/nano-TiO₂/carbon additives composites is around 245 °C. Therefore, the working ambient temperature of MA/nano-TiO₂/additive composites should be lower than 245 °C.