A reversible crosslinking structures of PAN fibers during heating in inert atmosphere

摘要

It is found that chemical crosslinking take place between nitrile groups of adjacent polyacrylonitrile molecules when heated at temperature between 170-230 °C in inert atmosphere,which is proved by its insolubility in concentrated sulfuric acid.However,after heat treatment in an inert atmosphere above 230 °Cfor one hour,the derived fibers become resolvable again in sulfuric acid,meaning the formed crosslinking structure,probably-C=N-N=C-bonds,is reversible.Oxygen in the atmosphere inhibit such a kind of crosslinking even oxidation is necessary for a thermostable and irreversible structure.