Isoconversional approach for the non-isothermal decomposition kinetics of guanylurea dinitramide (GUDN)

• The thermal decomposition of guanylurea dinitramide (GUDN) is studied by isoconversional method.
• The thermal decomposition products from GUDN are identified using TG-MS.
• Kinetic parameters are obtained from both ‘Isoconversional’ and classical ‘Kissinger’ methods.
• Isothermal kinetics of GUDN was predicted from isoconversional method and a decomposition mechanism for GUDN is proposed.

The thermal decomposition of a high-energy oxidizer viz., guanylurea dinitramide (GUDN) has been studied by non-isothermal thermogravimetry (TG) and thermogravimetry combined with mass spectrometry (TG-MS). Isoconversional method of Vyazovkin (VZ) was used to investigate the dependence of activation energy (Ea) on conversion (α). A strong dependence of Ea on α, where the Ea increases steadily for up to an α of ∼0.6 followed by a marginal increase and reaches ∼435.0 kJ mol−1 at the end of the reaction. Ea has also been determined for GUDN using Kissinger’s method. A comparison of the results from Kissinger and isoconversional method shows that the activation energies from these methods are comparable. Using the model free isoconversional method, the isothermal conversion as a function of time at two different temperatures was also computed. The evolved gases during the decomposition of GUDN were analyzed by TG-MS which revealed the formation of ions corresponding to N2, O2, NH3, H2O, N2, NO, methane diimine, isocyanic acid, N2O, NO2 and urea.