OPTICAL STUDIES OF PYROLYZED POLYACRYLONITRILE.

The results of measurements of the optical absorption spectra. IR absorption spectra, thermogravimetric analysis, and elementary analysis of pyrolyzed polyacrilonitrile are presented as a function of the pyrolysis temperature and of the duration of pyrolysis. At the temperature below 200 degree C, an intermediate phase was discovered, containing conjugated CN sequences and a completely unreacted carbon backbone. The optical absorption data imply that the resulting polymer is semiconductor with a delocalized pi -electron system and an energy gap near to 2. 5 ev. For temperature above 260 degree C, the weight loss rapidly increases, and the absorption edge gradually broadens and shifts to lower energies. The resulting polymer (after higher-temperature pyrolysis) contains CN and C equals C minus C conjugation sequences, but appears to be a complex structure consisting of a mixture of different chemical species.