Preparation, thermal and structural properties of n-octadecane/melamine formaldehyde nanocapsules embedded cement mortar for energy storage application in buildings

Abstract

Phase change materials (PCM) integrated into building fabrics plays an important role in achieving energy efficiency in buildings through thermal energy storage. The incorporation of nanotechnology-based heat storage materials into building fabric materials are becoming increasingly popular in recent times. From this perspective, a novel nanoencapsulated PCM (NePCM) embedded cement mortar was developed and its thermal energy storage and structural properties were investigated, experimentally. In-situ polymerization technique was used to prepare the nanocapsule containing n-Octadecane as the PCM and melamine formaldehyde as the shell material. The particle size analysis results reveal that the size of NePCM ranged from 76 nm to 530 nm. The NePCM resulted in an appreciable encapsulation efficiency of 60.14 % with a melting temperature and latent heat of fusion of 26.01 °C and 122.24 kJ/kg, respectively. The NePCM exhibited good chemical and thermal stability. The pure PCM and the NePCM were embedded into cement mortar with varying proportions for the preparation of cube specimens and based on which a comparative study was performed. During curing the cube specimens for 28 days, leakage of the pure PCM from the cement mortar was noticed to some extent. On the other hand, no leakage issues were found in the NePCM embedded cement mortar, as a result of the shell material which protected the PCM from leaking. The PCM and NePCM embedded cement mortar cube specimens exhibited an excellent compressive strength of 56.8 MPa and 48.16 MPa, respectively. However, by increasing to 6 wt% of PCM content in cement mortar, the cube samples of PCM embedded cement mortar compressive strength was reduced to 44.41 %. Thus, the developed NePCM with improved thermal and structural properties can achieve enhanced energy storage and passive cooling in buildings without sacrificing the structural stability.