Preparation and characterization of hydrated salts/silica composite as shape-stabilized phase change material via sol-gel process

A novel shape-stabilized phase change material composite was prepared by impregnating the mixture of hydrated salts (Na2SO4 center dot 10H(2)O-Na2HPO4 center dot 12H(2)O) into porous silica matrix obtained by sol-gel process and further coated with polyvinylpyrrolidone (PVP) to improve the thermal cycling performance. The chemical compatibility, morphology and phase change properties were investigated by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), hot-stage polarizing optical microscope (HS-POM) and differential scanning calorimetry (DSC). Confined in the silica matrix, phase segregation of the hydrated salts was inhibited and subcooling was slightly mitigated. No leakage was observed during the solid-liquid phase transition even when the mass ratio of hydrated salts to silica was as high as 70:30. Results showed that the melting enthalpy of the composite can reach 106.2 kJ/kg with the melting temperature at 30.13 degrees C and there was no significant enthalpy loss after 30 thermal cycles. (C) 2014 Elsevier B.V. All rights reserved.