Differential thermal analysis of smectite - With special reference to endothermic peaks around 100.DEG.C.

Differential thermal analysis of mono- and divalent cationic derivatives of Kunimine montmorillonite were performed under static air and N2 gas flow atmosphere. The DTA curves were remarkably varied with sample weight, atmosphere, and exchangeable cation of montmorillonite. Under the atmosphere of static air, endothermic peaks on DTA curves around 100°C could be classified into three categories such as (1) single peak with small shoulder on the low temperature side, (2) double peak, and (3) three peaks. On the other hand, in N2 gas flow atmosphere, monovalent cationic derivatives showed single endothermic peak on DTA curves for samples equilibrated with atmosphere. Divalent derivatives showed double peak in the same experimental conditions. The Li derivatives presented the only exception in this series.