Thermal decomposition kinetics of ammonium dinitramide–guanylurea dinitramide mixture analyzed by isoconversional methods

The thermal decomposition kinetics of a mixture of high-energy oxidizers ammonium dinitramide (ADN) and guanylurea dinitramide (GUDN) have been studied by nonisothermal differential scanning calorimetry (DSC). Friedmanʹs and Vyazovkinʹs advanced isoconversional (AIC-V) methods were used to investigate the dependence of activation energy (Ea) on conversion (α). A strong dependence of Ea on α was observed, indicating a complex decomposition process. Ea is ∼165–175 kJ mol−1 at the start of the reaction, then reaches a maximum of ∼196–199 kJ mol−1 at α = ∼0.4, followed by a strong decrease to ∼135 kJ mol−1 near the end. Ea has also been determined for the mixture and the individual components using Kissingerʹs method. Our results suggest that the decomposition of ADN greatly influences the observed Ea dependence on α. This is further supported by Fourier transform infrared (FTIR) results and the enthalpy values of exothermic decomposition.