Thermal degradation kinetics of newly synthesized arylazo pyridone dyes

Thermal degradation properties of the newly synthesized azo dyes derived from 6-hydroxy4-methyl-2-okso-1,2-dihydropyridine-3-carboxamidewere examined Depending on the nature of substituent that is located on the para position of the diazo components of azo pyridone dyes, different thermal stability can be obtained The thermal behaviour of the present dyes has been determined using thermogravimetric analysis (TGA), derivative thermogravimetry (DTG) and differential thermal analysis (DTA) On the basis of this method, non-isothermal kinetics was monitored To explain kinetics behavior of the investigated dyes during their degradation in an inert atmosphere, ASTM E698, ASTM E2890, Friedman’s (FR), OzawaFlynn-Wall (OFW) as well as Kissinger-Akahira-Sunose (KAS) isoconversional (modelfree) methods were applied. Numerical optimization was used in order to judge fitting capabilities including simulated and experimental curves, for estimated kinetic parameters It was found that different thermal stabilities of various dyes are the consequence of their different chemical structures, including diverse substituents. It was shown that significant difference in reactivity for hydroxy substituted and unsubstituted dyes is a consequence of reactivity dissimilarities between •OH and H• species.It was assumed that reactions with •OH are characterized with changing in limiting stage, from kinetic to diffusion controlled The numerical optimization shows a good fitting correlation between experimental and simulated process data Based on multi-level conversion analysis, using differential (FR) and integral (OFW and KAS) model-free methods, the all dyes, exhibit the different E-conversion dependency