Synthesis and characteristics of hygroscopic phase change material: Composite microencapsulated phase change material (MPCM) and diatomite

• A new kind of hygroscopic phase change material was prepared.
• The SiO2 shell can improve the thermal properties of the composite.
• The SiO2 shell can prevent the melted phase change material from leaking.
• The composite has a good hygrothermal performance.
• The composite can moderate both the indoor temperature and relative humidity.

This paper prepared a new kind of hygroscopic phase change material using MPCM and diatomite. The composite can absorb/release not only thermal heat, but also moisture. The shell material of MPCM was prepared with methyl triethoxysilane (MTES) by sol–gel method, and a kind of alkane mixture was used as the core material. The diatomite was used as hygroscopic material. The morphology of the microcapsules and the diatomite were measured by the scanning electron microscopy (SEM). The thermal properties of MPCM and the composite MPCM/diatomite materials (CMPCM) were analyzed with differential scanning calorimetry (DSC). The thermal gravimetric analysis (TGA) was used to study the thermal stability of MPCM and CMPCM. The moisture transfer coefficient and moisture buffer value (MBV) of the diatomite and CMPCM were measured. The DSC results showed that the microcapsules were encapsulated in the SiO2 shell. The TGA results showed that the microcapsules and CMPCM have a good thermal stability. The measurements of the moisture transfer coefficient and moisture buffer value (MBV) of CMPCM, diatomite, gypsum board and wood showed that CMPCM has a better hygroscopic performance. The hygroscopic phase change material can moderate both the indoor temperature and moisture.