Polyacrylonitrile Precursor Fibers for Conversion to High-Modulus, High-Strength Fibers. Volume II. Mass Thermal Analysis

摘要

The successful conversion of polyacrylanitrile (PAN) fibers to high-strength, high-modulus fibers depends in part on an understanding of the thermal and oxidative reactions of this polymer system. Described is the application of new analytical techniques to identify the dominant chemical reactions that are involved in the transformation of a PAN precursor to a graphitizable carbon fiber. The results indicate that, despite its popular acceptance for many years, the machanism that postulates intramolecular cyclization to yield a linear ladder polymer has no basis in fact. An interpretation consistent with the present results involves a series of elimination reactions, followed by intermolecular crosslinking and cyclization induced by dipole interactions between pendant nitrile groups. The chemistry of oxidative stabilization of PAN at moderate temperatures is also presented.