Novel green and sustainable shape-stabilized phase change materials for thermal energy storage

Abstract

Poly (ethylene glycol) (PEG) blended with poly (L-lactic acid) (PLLA) as novel green and sustainable shape-stabilized phase change materials (PCMs) were prepared and characterized in this study. The miscibility and morphology of the blends played an important role in the properties of the PCMs. The partial miscibility between PEG and PLLA resulted in suitable latent heat and a low leakage percentage of PCMs. The typical spherulite structure with a Maltese cross was examined in neat PLLA, as observed using polarized optical microscopy. However, the addition of PEG to PLLA led to the formation of ring-banded spherulites due to the presence of PEG altering the aggregation and twisting the PLLA lamellae. These PLLA crystalline structures can capture liquid (including molten PEG), stabilize the shape, and prevent leakage. The thermal mechanical analysis results indicated that the thickness of the PEG/PLLA blends was not significantly changed during the phase change process. The PEG/PLLA 75/25 blends exhibited appropriate film forming properties and mechanical strength. Moreover, differential scanning calorimetry analysis demonstrated the largest latent heat of melting (130.26 J/g), which could have great potential for developing novel phase change materials for thermal energy storage.