Synthesis, characterisation and thermal degradation studies of copolymer resin

Copolymer (2,4-dihydroxybenzoic acid-phenyl hydrazine-formaldehyde (2,4-DBPHF)) has been synthesised using monomers 2,4-dihydroxybenzoic acid, phenyl hydrazine and formaldehyde in 1:1:2 molar proportions. The structure of 2,4-DBPHF copolymer has been elucidated on the basis of elemental analysis and various physicochemical techniques, such as ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy,¹H-NMR spectroscopy and¹³C-NMR spectroscopy. Detailed thermal degradation study of this new copolymer has been carried out to ascertain its thermal stability. Thermal degradation curve is discussed, which shows three decomposition steps. The activation energy (E_a) and thermal stability have been calculated by using Freeman–Carroll, Sharp–Wentworth, Friedman, Chang and Coats–Redfern methods. Thermodynamic parameters such as 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.