Effect of the solvent type on the formation and physical properties of polyacrylonitrile fibers via a solvent-free coagulation bath

Abstract

Polyacrylonitrile (PAN) fibers were fabricated via a dry-jet wet-spinning technique, and a solvent-free coagulation bath system was adopted. The effects of different types of dope solvent on the formation and physical properties of the PAN fibers were investigated. Dimethylformamide and dimethyl sulfoxide (DMSO) were selected as the solvents and were added to a spinning solution consisting of 18 wt % PAN. The PAN fibers were examined with field emission scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis. The field emission scanning electron micrographs revealed that the PAN fibers with the DMSO solvent exhibited a more circular shape and a smoother skin. The PAN fibers with the DMSO solvent had their glass-transition temperature (Tg) at 121°C. This study indicated that the different types of dope solvent used in the dope preparation did not affect Tg of the PAN fibers because of the solvent-free coagulation bath system; however, they significantly affected the physical formation of the PAN fibers.