Accelerating the stabilization of polyacrylonitrile fibers by UV irradiation

Abstract

Commercial polyacrylonitrile (PAN) fibers, widely used as carbon fiber precursors, were treated with ultraviolet (UV) light without any photo-initiators and its effects on the structural changes of PAN were investigated. Easily accessible UV irradiation produced free radicals by breaking the C-H bonding in PAN, leading to reducing cyclization temperature and activation energy. Dynamic mechanical analysis indicated a decrease in storage modulus of PAN fibers with increasing UV irradiation time below glass transition temperature. It is suggested that UV irradiation and the subsequent thermal treatment could offer an efficient stabilization by reducing the cyclization temperature and process time. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.