Gel spinning of polyacrylonitrile fibers with medium molecular weight

A new gel-spinning method was employed to prepare polyacrylonitrile (PAN) fibers from a PAN spinning solution with dimethylsulfoxide and water as a mixed solvent. Aging at 25 degrees C for 120 min brought the spinning solution to the sol-gel transition and a three-dimensional gel formed before entering the coagulation bath. The as-spun fibers from the solution at the sol-gel transition and in the gel state possess a circular cross-section. Compared with dry-jet wet-spun fibers, the gel-spun fibers have a more compact structure, fewer voids and better mechanical properties after a three-stage drawing. Moreover, the gel-spun fibers obtained from the extraction bath have a more homogeneous microstructure and better packed supermolecular structure. The physical properties of the extracted gel-spun fibers are also better than those of coagulated gel-spun fibers. (C) 2010 Society of Chemical Industry