Thermal degradation of a polyphenylquinoxaline in air and vacuum

A series of poly[2,2′-(1,4-phenylene)-6,6′-bis(3-phenylquinoxalines)] were prepared. These polymers had all the same repeating unit but differed in molecular weight and polymer chain endings. The thermal degradation characteristics in air and vacuum were determined by isothermal weight loss measurements. The temperature coefficients of thermal degradation (apparent activation energies) were also determined. Whereas the apparent activation energies for degradation in air showed a considerable dependency on the type of polymer chain endings, no such effect was observed upon pyrolysis in vacuo. A possible chain-end unzipping mechanism of degradation in air is postulated to explain these results.