Abstract
Many of dehydration of inorganic salts are reversible and are influenced by the vapor pressure of water evolved. These reactions greatly depend on the experimental conditions such as the sample size, the nature of the atmosphere, the crucible shape and the heating rate, etc.
Recently, several controlled rate thermal analysis (CRTA) techniques have been actively studied. Here, we propose the dynamic rate control (DRC) method as a high resolution technique that belongs to the CRTA. In this technique, the heating rate of the sample is dynamically and continuously varied in response to the changes in the sample's decomposition rate. The presented data of the dehydration of inorganic salts (CaSO4·2H2O, MgSO4·7H2O and CuSO4·5H2O) show improved resolution as compared with the conventional TG thermograms. At the DRC method, the dehydration proceeds nearly under the equilibrium conditions. Since the beginning of the dehydration shifts to the lower temperature region, the change of DRC curves becomes much more distinct. Also, the reaction clearly occurs in several steps, with a plateau characterizing to the dehydration mechanism. This method is especially proved to be very effective technique in the detection of intermediate products.
