Original Article Studies

on structurally different benzoxazines: curing characteristics and thermal degradation aspects S Shamim Rishwana1, A Mahendran2 and CT Vijayakumar3 Bisbenzoxazines were prepared by the condensation of the respective bisphenols bisphenol A (BA), indane bisphenol (IBP), and spirobiindane bisphenol (SBI) with paraformaldehyde and aniline. The apparent activation energies for the polymerization curing process (Ea-C) and the degradation process (Ea-D) were calculated using Flynn–Wall–Ozawa, Vyazovkin, and Friedman methods. The variation in Ea-C noted for the thermal curing of different bisbenzoxazines is attributed to the operation of different mechanisms for the curing process. The variation of the Ea-D for the degradation of spirobiindane benzoxazine polymerized at high temperature was different from the other materials investigated and is attributed to its complex structure. The volatile products obtained during the thermal degradation of the polymers were analyzed using thermogravimetric–Fourier transform infrared analyses. Aniline was found to be the major product and was released during the primary degradation. At higher temperatures, breakage of the isopropylidine, indane, and biindane structural entities were favored