Thermal properties and related core/shell structure of n-tetracosane microencapsulated by calcium carbonate

Phase change materials show great promise as a way of thermal energy storage. A number of alkanes and these mixtures with melting point below 50 °C have been investigated to develop the microcapsules. However, there have been few investigations aimed at harnessing heat from environmental temperatures around 50 °C. Here, n-tetracosane, which has a melting point of 51 °C, was successfully microencapsulated in a calcium carbonate shell through a self-assembly technique. The structural characterization was conducted by the method of Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy. The encapsulation ratio of the phase change material into the shell was estimated based on the mass loss of the microcapsules due to heating and the differential scanning calorimetry analysis. A maximum encapsulation ratio of 53% was achieved, and the effects of the encapsulation ratio on the effective thermal conductivity of the microcapsules were evaluated by a steady-state method. In addition, heating–cooling cycles were demonstrated in composites of the microcapsules and building plaster. Repeatable thermal energy storage and release characteristics were achieved suggesting that this material is a potential candidate material for management of high temperatures.