Influence of External Tension on the Structure and Properties of Melt-Spun PAN Precursor Fibers during Thermal Oxidation

Effects of external tension during oxidative stabilization of melt-spun polyacrylonitrile ( PAN) precursor fibers on the structure and properties were investigated. The results showed that the external tension had distinct effects on the chemical and crystal structures, carbon yield, density, and tensile strength of pre- oxidized melt- spun fibers, while had little effects on elemental contents. With external tension increasing, the extent of reaction ( EOR), aromatization index ( AI), carbon yield, and density of pre- oxidized melt- spun fibers showed an initial increase and then a subsequent decrease, while, crystal size, crystallinity and the tensile strength appeared to first fall and then rise. When the external tension was 0.56 cN . dtex . 1, the tensile strength of resulting carbon fibers reached maximum.