STRUCTURAL STUDY OF POLYACRYLONITRILE FIBERS DURING OXIDATIVE THERMAL-DEGRADATION BY PYROLYSIS-GAS CHROMATOGRAPHY, SOLID-STATE C-13 NUCLEAR-MAGNETIC-RESONANCE, AND FOURIER-TRANSFORM INFRARED-SPECTROSCOPY

The structural changes during the oxidative thermal degradation of poly(acrylonitrile) (PAN) fibers were studied by high-resolution pyrolysis-gas chromatography (PyGC), solid-state13C nuclear magnetic resonance (NMR), and Fourier transform infrared (FT-IR) spectroscopy. The main stabilization mechanism of the PAN fibers to form cyclic ladder structures was confirmed by PyGC,13C NMR, and FT-IR. Furthermore, the contribution of dehydrogenation and/or dehydrocyanide reactions to form conjugated polyene structures suggested by the data of PyGC, especially for the PAN fibers stabilized at relatively higher temperatures, was also supported by those of13C NMR and FT-IR. © 1990, American Chemical Society. All rights reserved.