Bio-based Polylactic acid/Polyurethane blends with good recyclability and excellent shape stability for solar thermal energy storage

Abstract

Solid-solid phase change materials (SSPCMs) with low volume change, no leakage, lack of corrosion and extensive service lives are used more and more widely in the application field of thermal energy storage (TES). In this study, eco-friendly polylactic acid (PLA)/polyurethane (PU) phase change composites with good recyclability and excellent form stability for TES were obtained by melt blending in a twin-screw eccentric rotor extruder. The experimental results show that the introduction of PLA is helpful to enhance the mechanical strength and leak-free performance of the PLA/PU composites. When the content of PLA achieved 20% in the PLA/PU composites, the relative enthalpy efficiency (η) of PP-20 is 79.14%, which is beneficial for the function of TES. Especially, PP-40 showed excellent flexibility, reversibility and durability whose tensile stress (14.0 MPa) and tensile strain (48.15%) were pretty good at room temperature. After reprocessed many times, PP-40 showed good recyclability whose enthalpy of fusion reduced (60.69 J/g) but could still reach 91.51% of the original. The above results imply that the PLA/PU composites provide an efficient way for the green use and reprocessing of SSPCMs in the field of TES.