Effect of draw ratio and coagulant composition on polyacrylonitrile hollow fiber membranes

Asymmetric polyacrylonitrile (PAN) hollow fiber membranes were fabricated via the dry-jet wet spinning process. The effects of the draw ratio and the DMF content in the coagulation bath on the mechanical properties, permeation, and morphology were investigated. The external surface and cross-section of the resulting hollow fibers were examined using a scanning electron microscope (SEM) and the thermal properties were measured. Additional characterization using X-ray and porosity measurement suggested the improvement in molecular orientation. The results show that the maximum draw ratio increased with the DMF content in the coagulant. The pure water permeability increased while the retention decreased with the increase of the draw ratio. On the other hand, both the permeability and the retention increased with the DMF content.