engleski

Isothermal and non-isothermal kinetics of thermal decomposition of ammonium perchlorate

The results of numerous investigations of ammonium perchlorate decomposition process show that there is a considerable discrepancy in the values of the activation energy obtained. This discrepancy may arise from several reasons: the use of different kinetic models in treating kinetic data, different experimental methods applied and different testing conditions used. One more additional reason probably lies in the fact that the decomposition process is unusually complex. In this paper differential scanning calorimetry and thermogravimetric analysis are used for the thermal characterisation and for the evaluation of the kinetic parameters of the ammonium perchlorate thermal decomposition process. Experiments were performed under different testing conditions. Kinetic parameters were evaluated applying Flynn-Wall and Ozawa non-isothermal methods. It is found by isothermal methods that the complex decomposition mechanism, which includes three parallel (in)dependent reaction steps, may be described by three reaction models: the first step by the Šestak-Bergreen general reaction model ; the second step by the reaction model controlled by nucleation according to exponential law, and the third step by the contracting volume reaction model. It is also found that the values of activation energies obtained by the isothermal and non-isothermal methods are in satisfactory agreement.

kinetics; thermal decomposition; ammonium perchlorate

nije evidentirano