Influence of the isothermal treatment conditions on the phase transformation of the polyacrylonitrile yarn material into the structure of thermostabilized fiber

Abstract

The influence of the isothermal treatment conditions on changes in the phase composition, mean size of coherent scattering domains, and texture of polyacrylonitrile yarn in the course of thermostabilization was studied by X-ray diffraction analysis. The two-step isothermal treatment involving preliminary short heat treatment at a lower temperature stimulates structural transformations of the polyacrylonitrile yarn material and formation of a new finely dispersed phase of the thermostabilized fiber.