Kinetics of thermal decomposition and antimicrobial screening of terpolymer resins

Polycondensation technique was employed to synthesize terpolymer resins of anthranilic acid, urea, and formaldehyde (AUF-I, II, and III) in dimethyl formamide medium with varying mole proportions. The terpolymer was characterized by infra-red, nuclear magnetic resonance ( 1 H and 13 C) spectroscopy, gel permeation chromatography (GPC), and scanning electron microscopy (SEM). The thermal decomposition pattern and the kinetics of thermal decomposition of the terpolymers were investigated by thermogravimetric analysis (TGA) in a static nitrogen atmosphere at a heating rate of 20 °C/min. Freeman–Carroll and Sharp–Wentworth methods have been adopted to evaluate the kinetic and thermodynamic parameters such as thermal activation energies ( E a ), order of the reaction ( n ), entropy change (Δ S ), free energy change (Δ F ), apparent entropy ( S* ), and frequency factor ( Z ). The thermal decomposition model for the terpolymers was also proposed using Phadnis–Deshpande method. The synthesized terpolymer resins were screened for antimicrobial activity against pathogenic bacteria and fungi. The resins show potent inhibition against bacteria such as Escherichia coli , Klebsiella , Staphylococcus aureus , and Pseudomonas aeruginosa and fungi viz. Aspergillus flavus , Aspergillus niger , Penicillium species , Candida albicans , Cryptococcus neoformans , and Mucor species .