Improvement of coumarin derived copolymer systems

In this study, a new coumarin derived monomer 3-benzoyl coumarin-7-yl-methacrylate (BKMA) was synthesized. At the characterization of compounds, FTIR, 1H-NMR and 13C-NMR techniques were used. A copolymer series of BKMA monomer with methyl methacrylate (MMA) at different compositions was prepared by free radical polymerization method. Copolymer compositions were determined with 1H-NMR spectra. From DSC analysis, the glass transition temperature of copolymers was decreased from 179 oC to 165 oC when the level of BKMA ratio decreased to 23% level. Thermal degradation kinetics of the copolymer system with 54% BKMA ratio was investigated in detail. For this purpose, TGA analysis at different heating rates was performed. A good agreement was found between the thermal decomposition activation energies of the that copolymer according to Flynn-Wall-Ozawa (E = 210.30 kJ/mol) and Kissinger (E = 212.28 kJ/mol) methods. The kinetic methods of Coats-Redfern, Tang, Madhusudanan, Van Krevelen and Horowith Metzger were used to determine the thermal decomposition mechanism of copolymer. The best agreement was obtained for the Van Krevelen methods (E = 213.68 kJ/mol, R = 0.9979). From these results, it was determined that the copolymer proceeded through a D3 three-dimensional diffusion type deceleration mechanism at the optimum heating rate of 20 oC/min.