Effect of functional groups on the thermal degradation of copolymers

Thermal degradation mechanisms of the copolymers of styrene (St) with methacrylonitrile (MAN) and alpha-methylstyrene (alphaMSt) were studied by pyrolysis gas chromatography (Py-GC) and thermogravimetry (TG). Thermal degradation of vinyl polymers in flash pyrolysis proceeded mainly in the competition between depolymerization and back biting reaction caused by abstraction of H atom at alpha-position in pen-penultimate unit. Monomer molecules were regenerated by depolymerization, and dimer, trimer and ologomers were produced by back biting reaction. Methyl groups at alpha-position of monomer unit strictly hindered the back biting reaction. The role of functional groups on the thermal degradation energies of main chain (Q(C-C)), apparent activation energies (DeltaE(a)) obtained by Ozawa's method from the TG curves at various heating rates. Effect of chemical reactivity of - Cequivalent toN group in MAN unit on the thermal degradation was clarified by the controlled rate thermogravimetry (CRTG). Copyright (C) 2002 John Wiley Sons, Ltd.