Thermal decomposition of hydromagnesite Effect of morphology on the kinetic parameters

Non isothermal decomposition of synthetically prepared hydromagnesite phase with two different morphologies (2-D micro sheets and nests) was studied in dynamic nitrogen atmosphere by thermogravimetric analysis, differential thermogravimetric analysis, and differential scanning calorimetric techniques. Two different kinetic models, i.e. the Friedman isoconversion and the Flynn-Wall methods were employed for the analysis of thermal decomposition. The apparent activation energy (E (a)) of the hydromagnesite phases having 2-D micro sheet and nest morphology were calculated and compared. The activation energy of nest morphology was found to be relatively higher than 2-D micro sheets. The higher activation energy for the relatively close packed 'nest' morphology is attributed to the difficulty of thermal transport in the core.