Kinetic study of the thermal and oxidative degradations of poly(arylenether)s containing quinoline units

The degradations of five aromatic thermoplastics, in whose repeating units various structures are linked to the same -ArCOQCOAr- moiety (where Ar = 1, 4-substituted phenylene and Q = 3,7-substituted quinoline), were performed in dynamic heating conditions in the temperature range 35-950 degrees C, un der nitrogen how and in static air atmosphere. Experiments under nitrogen s uggested that degradations started by random chain scissions, to which bran ching and crosslinking superimposed at higher temperature, with the formati on of residues stable up to 950 degrees C; those in oxidative environment i ndicated that degradations were due to several processes which were simulta neous at low heating rate and that oxidative stages were involved, as suppo rted by the complete weight loss before the overall temperature scanning. T he apparent activation energy values associated with the first degradation stage were obtained by the Kissinger method. Results in inert atmosphere su ggested that different linkages were involved in the initial chain scission processes of various polymers and that the comprehensive degradation mecha nisms were different from those in air. Anomalous double Kissinger straight lines were found for one of the polymers investigated. The results were di scussed and compared with those previously obtained for a similar group of aromatic polymers. (C) 1999 Published by Elsevier Science Ltd. All rights r eserved.