Thermal behavior of some polyarylene ethers: A comparative study of the kinetics of degradation

The degradation of four aromatic thermoplastics containing carbonyl, ether and sulfone linkages was performed in a thermogravimetric analyzer in both nitrogen and air environments, in isothermal and dynamic heating conditions. The obtained results suggest that degradations started by random chain scission under all the experimental conditions. Under N-2 flow branching and crosslinking were superimposed on the initial process, while in air complete oxidative degradation occurred. The apparent activation energies associated with the first degradation stage were evaluated and correlated with the linkages present in the polymer chains. The obtained values indicate that the chemical reactions occurring under nitrogen are different from those in air. In addition, the ratio of the chain scission rate to the branching and crosslinking rates in nitrogen is dependent on temperature in isothermal experiments and on heating rate in the dynamic ones. A comparison with poly(ether ether ketone) is also reported.