Synthesis, characterization and thermal degradation of 8-hydroxyquinoline-guanidine-formaldehyde terpolymer

Terpolymer (8-HQGF) has been synthesized using the monomers 8-hydroxyquinoline, guanidine, formaldehyde in 1:1:2 molar proportions. The structure of 8-HQGF terpolymer has been elucidated on the basis of elemental analysis and various physicochemical techniques, i.e. UV-Visible, FTIR-ATR and ¹H NMR spectroscopy. Detailed thermal degradation study of the new terpolymer has been carried out to ascertain its thermal stability. Thermal degradation curve is discussed which shows two decomposition steps (265-475 °C and 540-715 °C). Sharp-Wentworth and Freeman-Carroll methods have been used to calculate activation energies and thermal stability. The activation energy (E_a) calculated by using the Sharp-Wentworth (21.98 kJ/mol) has been found to be in good agreement with that calculated by Freeman-Carroll (23.57 kJ/mol) method. Thermodynamic parameters such as free energy change (ΔF), entropy change (ΔS), apparent entropy change (S^∗) and frequency factor (Z) have also been evaluated on the basis of the data of Freeman-Carroll method. The order of reaction (n) is found out to be 0.9979.