Thermal decomposition of oxamide and associated kinetic parameters through thermogravimetric analysis

Abstract

Organic additives are used for pellet forming in the manufacturing process of MOX fuels. In order to understand their degradation during the sintering process, the thermal decomposition of oxamide has been investigated using thermogravimetric analysis. The temperature range of experiments was 30–1000 °C, and 1, 2, and 5 °C.min−1 heating rates were used. The apparatus was under a constant flow of argon mixed with 4 vol% of dihydrogen. The kinetic parameters were found to be E=100±7kJ.mol−1,A=2.5*108min−1 and n=0.32 using Friedman's isoconversional method. With the kinetic triplet, a predictive model of the thermal decomposition of oxamide was established by integrating the conversion rate in non-isothermal conditions. The model calculations were compared to experimental data, and the results were deemed satisfactory. This study is helpful to understand the degradation process taking place in the sintering furnace and constitutes a first step in the decorrelation of the effect of thermolysis and that of radiolysis on the organic additives used for MOX fuel pellets manufacturing.