AN XRD CHARACTERIZATION OF THE THERMAL-DEGRADATION OF POLYACRYLONITRILE

Thermal degradation of polyacrylonitrile (PAN) has been studied by com bined differential thermal analysis, thermogravimetry, and XRD analysi s. On the basis of the experimental observations, it has been suggeste d that the intramolecular polymerization of nitrile groups to a conjug ated polyimine structure is initially limited to only the amorphous zo ne of PAN, which involves little evolution of off-gases. Polymerizatio n of nitrile group in the crystalline zone starts with the melting of crystallites with the evolution of off-gases from the amorphous-crysta lline zone interface. (C) 1995 John Wiley and Sons, Inc.