Developing microencapsulated 12-hydroxystearic acid (HSA) for phase change material use

Phase change materials (PCM) have an increasingly more important role as a thermal energy storage (TES) media. However, leakage problem of PCM causes limitation during their integration in TES systems. Therefore, the encapsulation of PCMs is attracting research interest to extend usage of PCMs in real TES applications in recent years. In this study, hydroxystearic acid (HSA) was encapsulated with polymethyl methacrylate (PMMA) and different PMMA comonomer shells via emulsion polymerization method for the first time in literature. HSA with high melting temperature range (74-78 degrees C) can widen the scope of using PCMs, and the encapsulated form can make it more versatile. The chemical structures, morphologies, and thermophysical properties of capsules were determined by FT-IR, SEM, DSC, TGA, and thermal infrared camera. Among the produced HSA capsule candidates, PMMA-HEMA is the most promising with latent heat of 48.5J/g with melting range of 47 to 85 degrees C. SEM analysis indicated that the capsules have spherical shape with compact surface at nano-micro (100-440nm) size range; however, some capsules exhibited agglomeration.