Possibility of Predicting the Thermal Stability of Copolymers Based on Thermogravimetric Analysis Data of Individual Polymers

Thermal degradation of polyarylene ketone of the general formula –[–O–C₆H₄–C(=O)–C₆H₄–O–C₆H₄–R–C₆H₄]_n– containing two species differing in chemical structure (R₁ = –C(CH₃)₂– and R₂ = ‒[(C₆H₄–C(=O)O)]–) and in the stability of the units, analyzed within the framework of a kinetic model that includes two parallel reactions involving units and products of their transformation. The predicted kinetic curve of mass loss was obtained by adding the experimental curves of degradation of individual polymers, taking into account the mass fraction of their units in the copolymer. This makes it possible to predict a relatively low temperature resistance of the copolymer, which is consistent with experimental data. The contributions of the three stages of degradation and their activation energies were estimated by the method of nonlinear regression analysis, which includes simultaneous processing of all kinetic information obtained at different heating rates. The correspondence of the found values of the activation energies of the copolymer to the activation energies of the degradation of individual polymers confirms the adequacy of the proposed process model.