Thermal Properties of γ-Cyclodextrin Nitrates with Various Degrees of Nitration

The aim of this paper was to analyze the thermal properties of gamma-cyclodextrins with different degrees of nitration and to determine the kinetic parameters of their decomposition reactions. The differential scanning calorimetry was used to investigate six nitro derivatives of gamma-cyclodextrins obtained and characterized by various degrees of nitration. The tested samples differed in the number of esterified OH groups in gamma-cyclodextrins from 6.4 to 24.0 and nitrogen content from 6.3 to 14.1 %. It was concluded that the value of the heat of combustion increases with the nitrogen content and achieves the highest value (4.0 kJ/g) for nitrogen content 14.1 %. The thermal effect of decomposition was found to increase significantly and proportionally to the increased heating rate of the sample. The largest temperature shift of the decomposition process with changed heat flow rate was observed for the samples with the highest nitrogen content (13.7 % and 14.1 %). No influence of nitrogen content on the value of apparent activation energy for the obtained gamma-nitrocyclodextrins was observed, which may indicate that the initial stage of decomposition is independent from the nitrogen content. The determined kinetic parameters of the decomposition reaction make it possible to estimate the safe conditions for the synthesis, use and storage of gamma-nitrocyclodextrins and to determine parameters such as Self-Accelerating Decomposition Temperature (SADT), Adiabatic Decomposition Temperature (ADT24).