On the origin of order-disorder in drawn polyacrylonitrile

Drawn polyacrylonitrile can be characterized only insufficiently with regard to its molecular and supermolecular structures which substantially determine the physical properties. This paper points out that the so-called “superstructure” of polyacrylonitrile fibers can be cleared up after suitable thermooxidative treatment using x-ray small-angle scattering technique. The chemical reactions during the thermo-oxidative treatment lead to a “self-contrasting” effect so that the fibers as such are severely damaged yet information about the supermolecular structure can be obtained. The investigations show that changes in the course of fiber production (spinning, drawing, and annealing processes) affect alterations of the superstructure. The described method of investigation represents a so far unknown possibility for the purpose of detecting the supermolecular structure of drawn polyacrylonitrile.