Kinetics of the isothermal degradation of model polymers containing ether, ketone and sulfone groups

The kinetics of isothermal degradation of four model polymers containing ether, ketone and sulfone groups in the polymer chain was studied in order to investigate the influence of various groups on the apparent activation energy values (Ea) of degradation. Isothermal experiments were carried out in both flowing nitrogen and static air. Degradation Ea values were determined by both a literature method and a new method we set up recently and were compared with each other and with those previously obtained by us in the scanning mode. The results are discussed and a kinetic stability classification among various groups (sulfone > ketone > ether) is obtained, which is interpreted on the basis of the percentage of double-bond character of chain bonds. The picture of results confirmed the reliability of our method for determining Ea values of isothermal degradation directly from experimental weight loss data.