Studies on structurally different diamines and bisphenol benzoxazines

The compounds resorcinolbisbenzoxazine, quinolbisbenzoxazine, p-phenylene diaminebisbenzoxazine, and m-phenylenediaminebisbenzoxazine are prepared. The structural and thermal characterizations of the materials are done using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) and 13C NMR, and differential scanning calorimetry. Both FTIR and NMR studies reveal the presence of oxazine rings in the synthesized monomers. The curing exotherm of these bisbenzoxazines is much influenced by the nature of the aromatic unit present in the chosen compound and also on the type of the benzoxazine unit in the system. Curing kinetics is performed using Flynn–Wall–Ozawa, Vyazovkin, and Friedman methods. The apparent activation energies ( Ea-C) for the thermal curing of the synthesized monomers varied and are dependent on the nature and the position of the functional groups present in the compound. The highest Ea-C values are noted for the compounds having the functionalizations being para oriented.