Solvent-free preparation and performance of novel xylitol based solid-solid phase change materials for thermal energy storage

Novel polymeric solid-solid phase change materials (SSPCMs) were prepared through solvent-free bulk polymerization by employing polyethylene glycol (PEG) as phase change functional segments, diphenylmethane diisocyanate (MDI) as coupling agent and xylitol as curing agent. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), polarizing optical microscopy (POM), differential scanning calorimetry (DSC), accelerated thermal cycling testing and thermogravimetric analysis (TG) were conducted to study the chemical structure, crystalline properties, phase change properties, thermal reliability and stability of SSPCMs, respectively. The crosslinked structure gave the obtained SSPCMs solid-solid phase change process. XRD and POM results showed that SSPCMs have the same crystalline structure, lower degree of crystallinity and smaller crystal size with pure PEG. DSC results indicated that SSPCMs are capable of reversible storing and releasing latent heat in the temperature of −10 to 60 °C through phase transitions. Thermal cycling tests demonstrated that SSPCMs have good thermal reliability and chemical stability. TG results testified the thermal stability of SSPCM. The obtained SSPCMs exhibited great potential application in the field of thermal energy storage.