Preparation of Expanded Graphite/Paraffin-Based Composite Phase Change Materials (PCMs) via Low-Temperature In Situ...

In this study, an expanded graphite/paraffin-based phase change material (PCM) was efficiently and sustainably prepared via a low-temperature synchronous expansion-adsorption method. The mechanism was further elucidated utilizing FTIR, SEM, BET, XPS, XRD, TG-DSC, and VASP simulation calculations. The results indicate that since paraffin adsorption occurs during graphite expansion, it better adsorbs into the interstitial spaces of expanded graphite, further enhancing its leak resistance while improving thermal conductivity (0.20 W/(m·K)). The EG:Paraffin = 1:4 sample exhibits minimal pore volume (0.002667 cm³), indicating the fewest surface pores on the phase change material, demonstrating effective paraffin adsorption. Simultaneously, without excessive paraffin adsorption, the EG:Paraffin = 1:4 sample exhibited the lowest total weight loss at 71.3%. The interlayer spacing of expanded graphite was effectively increased at low temperatures, resulting in a final expansion volume of 203 mL/g. Throughout the system, the characteristic wax peaks remained distinctly present, indicating that the composite process between expanded graphite and wax was a physical mixture. This finding is consistent with both the XPS spectra and simulation calculations. This study provides an innovative method with greener, more energy-efficient, simplified preparation process to obtain the freshly synthesized porous graphite for the synchronous integration with PA, which can facilitate the rapid development of controllable microstructure and large-scale production of EG/PA-based composite PCMs.