Synthesis of eutectic PCM for application in cement-based construction materials

초록

In this study, a hydrophobic deep eutectic solvent (HDES)-based eutectic phase change material (PCM) was synthesized from naturally derived components to address the environmental limitations of paraffin-based PCMs and to develop thermally functional cement-based materials. Seventeen eutectic PCM compositions with varying molar ratios were prepared using L-menthol, thymol, decanoic acid, and 10-undecylenic acid. Thermal properties were evaluated by differential scanning calorimetry (DSC), and the L-menthol:10-undecylenic acid composition at a 1:1 molar ratio was selected for its superior latent heat and phase change behavior. The selected PCM was stabilized by vacuum impregnation into glass fibers, followed by sol-gel coating. Scanning electron microscopy (SEM) confirmed uniform PCM distribution within the fiber matrix. Cement paste specimens incorporating stabilized and non-stabilized PCMs (5 wt% and 10 wt%) were tested for compressive strength, microstructure, and thermal performance. Stabilized specimens achieved phase change efficiency up to 772.9% of the theoretical estimate, based on measured-totheoretical latent heat comparisons per gram of composite. The PCM's phase change temperature (2.7 degrees C) lies within the black-ice window (0-3 degrees C). However, direct incorporation of nonstabilized PCM caused severe strength loss, and stabilized specimens also showed partial reductions, consistent with prior reports of PCM-induced strength compromise. Overall, the developed PCM is more suitable for non-structural or secondary applications - such as exterior finishes, wallboards, and coatings - where thermal buffering can enhance energy efficiency and durability in cold-climate infrastructure.

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