Thermal decomposition behavior of oligo(4-hydroxyquinoline)

In this study, the kinetic parameters and reaction mechanism of decomposition process of oligo(4-hydroxyquinoline) synthesized by oxidative polymerization were investigated by thermogravimetric analysis (TGA) at different heating rates. TGA-derivative thermogravimetric analysis curves showed that the thermal decomposition occurred in two stages. The methods based on multiple heating rates such as Kissinger, Kim-Park, Tang, Flynn-Wall-Ozawa method (FWO), Friedman, and Kissinger-Akahira-Sunose (KAS) were used to calculate the kinetic parameters related to each decomposition stage of oligo(4-hydroxyquinoline). The activation energies obtained by Kissinger, Kim-Park, Tang, KAS, FWO, and Friedman methods were found to be 153.80, 153.89, 153.06, 152.62, 151.25, and 157.14 kJ mol(-1) for the dehydration stage, 124.7, 124.71, 126.14, 123.75, 126.19, and 124.05 kJ mol(-1) for the thermal decomposition stage, respectively, in the conversion range studied. The decomposition mechanism and pre-exponential factor of each decomposition stage were also determined using Coats-Redfern, van Krevelen, Horowitz-Metzger methods, and master plots. The analysis of the master plots and methods based on single heating rate showed that the mechanisms of dehydration and decomposition stage of oligo(4-hydroxyquinoline) were best described by kinetic equations of A(n) mechanism (nucleation and growth, n = 1) and D-n mechanism (dimensional diffusion, n = 6), respectively. POLYM. ENG. SCI., 54:992-1002, 2014. (c) 2013 Society of Plastics Engineers