Polymorphism of d-Mannitol in Zeolite-Added d-Mannitol-Based Phase Change Materials and Its Effect on Supercooling Degree

Xudong Tang, Junichi Ryu, Int. J. Thermophys., 44, 58 (2023).

D-mannitol, as a potential phase change material (PCM), has a wide range of applications in solar cooling, building heating, domestic hot water systems, and industrial waste heat recovery. However, the polymorphism exhibited by D-mannitol is also noteworthy for its long-term use in practical applications. In this work, eight typical zeolites with the potential to improve the supercooling of D-mannitol were used as additive to prepare D-mannitol-based PCMs with different zeolite content. Three polymorphs of D-mannitol were confirmed in cyclic differential scanning calorimetry measurement combined with X-ray diffraction and Fourier transform infrared analysis. We found that pure D-mannitol treated without zeolite exhibited a smooth differential scanning calorimetry melting curve attributable to the α-D-mannitol polymorph during the heat storage phase. When zeolite was added to the system, the α-D-mannitol showed a tendency to change to δ-forms during the cyclic experiment. Usually, in the initial stage of this transition, its appearance is visually slight on the DSC curve. This transition can be identified by X-ray diffraction and Fourier transform infrared analysis. The tendency increases with the addition of zeolite in the system or the number of cycles of cyclic experiments. Polymorphisms of D-mannitol affect thermal parameters, such as the melting point, when it is used as a phase change material. This research provides technical support for the practical application of D-mannitol as a phase change material in the future.