Thermal dissociation kinetics of solid and liquid ammonium nitrate

Thermogravimetry has been used to study the kinetics of the thermal dissoci ation of solid and liquid ammonium nitrate. Model-fitting and model-free ki netic methods have been applied to the sets of isothermal and nonisothermal measurements to derive kinetic characteristics of the processes. The appli cation of the model-fitting method to the isothermal data has demonstrated that both solid- and liquid-phase kinetics are characterized by a single ac tivation energy of similar to 90 kJ mol(-1) and by the model of a contracti ng cylinder. A model-free isoconversional method has also been applied to i sothermal and nonisothermal data and has yielded an activation energy of si milar to 90 kJ mol(-1), which is essentially independent of the extent of c onversion. The obtained kinetic characteristics have been assigned to the p rocess of dissociative sublimation/vaporization.