Gypsum-based Silica Gel Humidity-controlling Composite Materials: Preparation, Characterization, and Performance

Gypsum was used as substrate, and silica gel was mixed into substrate at a certain mass ratio to prepare humidity-controlling composites; moreover, the moisture absorption and desorption properties of gypsum-based composites were compared with adding different silica gel particle size and proportion. The morphological characteristics, the isothermal equilibrium moisture content curve, moisture absorption and desorption rate, moisture absorption and desorption stability, and humidity-conditioning performance were tested and analyzed. The experimental results show that, compared with pure-gypsum, the surface structure of the gypsum-based composites is relatively loose, the quantity, density and aperture of the pores in the structure increase. The absorption and desorption capacity increase along with the increase of silica gel particle size and silica gel proportion. When 3 mm silica gel particle size is added with a mass ratio of 40%, the maximum equilibrium moisture content of humidity-controlling composites is 0.161 g/g at 98% relative humidity(RH),3.22 times that of pure-gypsum. The moisture absorption and desorption rates are increased, the equilibrium moisture absorption and desorption rates are 2.68 times and 1.61 times that of pure-gypsum at 58.5% RH,respectively. The gypsum-based composites have a good stability, which has better timely response to dynamic humidity changes and can effectively regulate indoor humidity under natural conditions.