Synthesis of Biobased Phase Change Materials from Vegetable and Microalgal Oils and Melamine with Intrinsic Flame-retardancy

Phase change materials (PCMs) store and release thermal energy through reversible phase transitions, enabling applications in building insulation, thermal energy storage systems, and smart textiles. Fatty acids have emerged as promising organic PCMs due to their high energy storage capacity, thermal stability, and renewability. However, their high flammability limits large-scale implementation in building and energy applications. This study addresses this critical limitation by developing bio-based PCMs with intrinsic flame-retardant properties, synthesized from palm, soybean, and microalgal oils via chemical reaction with melamine, a nitrogen-based flame retardant. The conversion of fatty acids into amides was confirmed by FTIR, with characteristic absorption bands observed in the 3500–3000 cm.¹ and 1700–1500 cm.¹ regions. Differential Scanning Calorimetry (DSC) revealed increases in melting and freezing temperatures, while Thermogravimetric Analysis (TGA) demonstrated improved thermal stability and higher char residues (11–24%), indicating enhanced thermal resistance. In terms of flammability performance, melamine incorporation increased both flash and fire points and reduced combustion time by up to 89 %, confirming the successful synthesis of bio-based PCMs with integrated fire resistance. These materials represent a sustainable and safer alternative to fossil-derived PCMs, combining renewable sourcing, enhanced safety, and efficient thermal energy storage performance.