2.9. Thermogravimetry (TG)
The absorbed water from the Met granulates was measured using the Rigaku Dynamic TG–DTA system (Thermo plus TG8120). Thermal analyzers have a controlled rate thermal analysis mode that can be used to automatically raise the temperature for quasi-isothermal thermogravimetry. This mode makes it possible to isolate the various reactions that occur at similar temperature. The constant reaction-rate control mode was used for evaluating detailed evaporation behavior [19]. The weight of the samples was approximately 15 mg. The samples were loaded into aluminum pans and heated from 20 °C to 130 °C in a nitrogen atmosphere. The initial heating rate was 2 °C/min, and the water evaporation rate of 0.001%/s was maintained at a constant level.