Preparation and characterization of stearic acid/polyurethane composites as dual phase change material for thermal energy storage

Cross-linked polyurethane (PU) is a promising supporting material for phase change materials (PCMs) because it has excellent physical properties, high impact strength and relatively good chemical resistance. PU prepared from polyethylene glycol can also function as solid-solid PCMs. In this paper, PU/SA composites were synthesized as dual PCMs by entrapping SA into cross-linked PU through in situ polymerization. SA served as a PCM, while cross-linked PU served as both a PCM and supporting material. Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction (XRD), polarizing optical microscopy (POM), thermogravimetric analysis (TG) and scanning electron microscopy (SEM) were used to investigate the chemical structure and basic properties of PU/SA composites. The XRD and POM patterns indicate that the synthesized composite has a completely crystalline structure and defective crystallization compared with pristine PEG and SA. The maximum enthalpy of the composite in the heating (cooling) process reaches 167.1 J g(-1) (165.4 J g(-1)), which is 169.35% higher than that of PU. TG results show that the synthesized composites possess good thermal stability. It is clearly that the resulting PU/SA composites are sure to have great potential in thermal energy storage due to their large latent heat, suitable phase change temperature and high thermal stability.