Preparation and thermal properties of n-octadecane/molecular sieve composites as form-stable thermal energy storage materials for buildings

The n-octadecane/molecular sieve 5A composites as form-stable thermal storage materials were prepared by adsorbing liquid n-octadecane into the molecular sieve 5A. In the composites, the n-octadecane was used as thermal storage material, and the molecular sieve 5A acted as the supporting material. Fourier transformation infrared (FT-IR) spectroscope and scanning electronic microscope (SEM) were used to determine the chemical structure and microstructure of the n-octadecane/molecular sieve 5A composites. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA). The FT-IR analyses indicated that there is no chemical interaction between the n-octadecane and molecular sieve 5A. The SEM results showed that the n-octadecane was well adsorbed into the porous network of the molecular sieve 5A and there is no leakage of the n-octadecane from the composites even when it is in the melting state. The DSC results indicated that the n-octadecane/molecular sieve 5A composites exhibited the same phase change characteristics as the n-octadecane and their latent heats increased with the increase of the n-octadecane content in composites. The TGA results presented that the molecular sieve 5A can improve the thermal stability of the composites as form-stable thermal energy storage materials.

► The n-octadecane/molecular sieve 5A composites were prepared.
► Chemical structure and microstructure of composites were determined by FT-IR and SEM.
► Thermal properties and stabilities were investigated by DSC and TGA.
► The molecular sieve 5A can improve the thermal stability of the composites.