The Preparation And Performance Of Gypsum-based Humidity Controlling Materials

The text has chosen sepiolite with good performance and got materials with good adsorption/ desorption capabilities through activating with vitriol and CaCl₂ . The pore's structure is tested by BET and the microcosmic appearance is observed by SEM. Gypsum-composites are obtained by gypsum mixed with activated sepiolite. Adsorption/ desorption properties are tested by static absorption method and humidity controlling abilities are tested in both simulation condition and nature condition.The result shows that the best parameters in activation with vitriol is as this: the consistence of acid is 15%, and the ration of solid and liquid is 1 '. 20, and the time is 14 h. After that, the amount of humidity absorption can be reached at 30.35% and he amount of humidity desorption can be reached at -26%. After activated by CaCl₂, the amounts of adsorption and desorption for sepiolite are both improved. The relative humidity is higher, the amount of absorption is more, and the relative humidity is lower, the amount of desorption is more. In the same humidity, the amount of adsorption and desorption for Sepiolite are both improved when the content of CaCl₂ is increased. In the same condition, the sepiolite activated by CaCl₂ is better than that by acids. After activated, the pore's structure is changed. With the content of CaCl₂ increasing, the surface proportion is reduced, and pore volume is diminished, and average aperture is augmented. After activated by CaCl₂, the appearance of sepiolite transfers fibriform into petal-form.Gypsum-composites humidity controlling materials owns good performance of adsorption /desorption and responds properties. The properties of adsorption /desorption is related to sepiolite activated by CaCl₂: when mixed different sepiolite, Gypsum-composites' adsorption /desorption capabilities are better when it's sepiolite's capability is better, and Gypsum-composites' adsorption /desorption capabilities are better when mixed more sepiolite. When controlling humidity, samples with stronger absorption abilities can control relative humidity in a narrow range, and samples with weaker absorption abilities can control relative humidity in a broad range. If samples are used too small, relative humidity changes in a broad range, and can't meet require. If samples are used more, relative humidity changes in a narrow range, and the effect is obvious. If the absorption abilities of samples are too strong, it's desorption abilities will be restrained, so it is not propitious to humidity controlling. In nature conditions, Gypsum-composites samples can control relative humidity in 40%—70%, which is good for human's surviving and living.