Preparation and characterization of poly (N-methylol acrylamide)/polyethylene glycol composite phase change materials for thermal energy storage

The cross-linked poly (N-methylol acrylamide)/polyethylene glycol (PN-MA/PEG) with an interpenetrating polymer network (IPN) was prepared by emulsion polymerization as composite phase change material (CPCM). N, N′-methylene bisacrylamide (MBA) was used for crosslinking agent. The prepared CPCM was characterized by Fourier Transform Infrared (FT-IR) spectroscopy, X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), thermal cycle test, Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). FT-IR results stated that there is no chemical interaction between PEG and PN-MA. XRD results indicated that the introduction of PN-MA did not change the crystal type of PEG. PEG still exhibits crystallization behavior under the constraints of cross-linked PN-MA. The DSC results indicated that CPCM melts at 26.24 °C with a latent heat of 106.5 J/g and solidifies at 32.56 °C with a latent heat of 104.9 J/g. The TGA results indicated that the CPCM has good thermal stability and is suitable for thermal energy storage application. The results of thermal cycle test indicated that the macroscopic morphology and latent heat of CPCM were almost unchanged after 40 thermal cycles. SEM and TEM results indicated that the microscopic morphology of CPCM was spherical and the particle size distribution was around 145 nm.