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

Abstract

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 (Δ F), entropy change (Δ S), 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.