Kinetics of non-isothermal decomposition of three irganox-type antioxidants

In the present work a comparative kinetic study was performed on the thermal behavior of three antioxidants of IRGANOX-type (L101, L109 and L115) in dynamic air atmosphere under non-isothermal conditions. The TG-DTG data were obtained at heating rates of 5, 7, 10 and 15 K min(-1). The kinetic parameters were obtained by processing these data with strategies corresponding to Flynn-Wall-Ozava (FWO), Friedman (FR), Budrugeac-Segal (BS) and non-parametric kinetic (NPK) methods. The thermal degradation by all the three compounds take place in melted state, so that any kinetic models regarding the decomposition of solids are inapplicable. Only with the NPK method it was possible a separation between the two functions of the reaction rate. For the temperature dependence, f(T), an Arrhenius-type model was searched; for the conversion dependence, the Sestak-Berggren equation was suggested in order to discriminate between physical (in) and chemical (n or p) steps of a complex thermodegradation process.