Formation of Surface Morphology in Polyacrylonitrile (PAN) Fibers during Wet-Spinning

Abstract

The effects of concentration of dimethyl sulfoxide (DMSO) in the coagulation bath, draw ratio and extrusion speed on surface roughness of polyacrylonitrile (PAN) fibers prepared by wet spinning and dry-jet wet spinning were investigated. The surface roughness was much higher for PAN fibers produced by wet spinning than dry-jet wet spinning. The surface roughness of the fiber increased linearly with increasing concentration of DMSO in the coagulation bath. Higher roughness was observed at higher draw ratios during spinning. The surface roughness of the PAN fibers decreased initially until at 90m/h, then increased with further increases in extrusion speed. A mechanism for formation of PAN fiber surface morphology based on deformation of the soft skins of single fibers during solidification of PAN/DMSO solution caused by stress perpendicular to the fiber axis is proposed. The stress results from recovery of the aligned PAN macromolecules due to shear in the spinneret during extrusion.