High flame retardancy of oxidized polyacrylonitrile fibers prepared by effective plasma-assisted thermal stabilization and electron-beam irradiation

Abstract

We synthesized flame-retardant oxidized polyacrylonitrile (PAN) fibers with a high density of >1.4 g/cm(3) using an advanced stabilization method involving electron-beam irradiation and atmospheric plasma treatment. The electron-beam irradiation introduced oxygen-favored radicals in the fibers, leading to a decrease in their cyclization temperature. The plasma-assisted heat treatment accelerated the diffusion of oxygen species into the fibers for rapid oxidation. The treated PAN fibers showed high thermal stability and flame retardancy with the lowest total heat release value of 1.2 kJ/g, an Underwriters Laboratory V-0 rating, and the highest limiting oxygen index of 50.9%.