Thermal properties of 3-hydroxy fatty acids and their binary mixtures as phase change energy storage materials

In the present work, we describe the chemical synthesis of 3-HFAs as prominent derivatives of fatty acids and assess if they could be applied as phase change materials (PCM). In addition, 3-HFAs were obtained by depolymerization of a bacterial biopolymeric material, polyhydroxyalkanoate. Thermal properties of 3-hydoxyoctanoic, decanoic, and dodecanoic acids are reported for the first time. These materials showed the potential to be applied as PCM in temperature range from 33°C to 66°C. In order to expand the temperature range for application of 3-HFAs as PCM, eutectic mass ratios of three kinds of binary mixtures of 3-HFAs were calculated, and their properties were predicted using the Schröder-van Laar equation. Thermal properties of these mixtures were validated by differential scanning calorimetry (DSC) analysis. These results showed that eutectics considerably expanded the scope of applications of 3-HFAs as PCMs. 3-HFAs originating from biotechnologically obtained polyhydroxyalkanoates also showed potential to be applied in development of PCMs.