5th INTERNATIONAL CONGRESS ON KHAZAR SCIENTIFIC RESEARCH AND INNOVATION
PRELIMINARY INVESTIGATION ON THE MATERIAL PROPERTIES OF EXPANDED GRAPHITE STRUCTURES DOPED WITH PHASE CHANGE MATERIAL AND POLYMETHYL METHACRYLATE
Expanded graphite (EG) structures, with their exceptional levels of porosity, are considered ideal carrier materials for phase change materials (PCMs). The capillary effects of the pores enable the retention of PCMs within the EG structure, even in their molten state, making these materials a focal point for research in thermal energy storage. However, the inadequate mechanical properties of EG/PCM systems remain a significant challenge. This issue can be addressed by incorporating polymeric materials that can penetrate the EG structure in liquid form, alongside molten PCM. In this study, polymethyl methacrylate (PMMA), a polymer that dissolves in suitable solvents and can mix with molten PCM, was used to fabricate a composite structure. The composition consisted of 65 wt% EG, 25 wt% PCM, and 10 wt% PMMA, and a preliminary investigation was conducted on the resulting material properties. Microstructural, hardness, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) characterizations were performed. The results revealed that the addition of PMMA significantly enhanced the mechanical properties of the EG/PCM structure, increasing the hardness by approximately 2-fold. Thermal stability was also improved due to the presence of PMMA and EG, with the decomposition temperature increasing by approximately 30°C compared to the EG/PCM system without PMMA. While PMMA and EG serve as structural reinforcements and carriers without contributing directly to thermal storage capacity, the PCM component exhibited melting and solidification enthalpies of approximately 35 J/g. This value aligns well with the expected enthalpy for a 25 wt% PCM content based on the pure PCM enthalpy, demonstrating the homogeneity of the composite structure. This study highlights the potential of PMMA as a polymeric additive to address the mechanical limitations of EG/PCM composites while maintaining efficient thermal energy storage capabilities, paving the way for future applications in energy storage systems.
