Thermally crosslinkable poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion-exchange fibers

The aim of this study was to prepare poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion-exchange fibers using the electrospinning technique and a post-thermal treatment. First, intermediate PSSA-MA/PVA fibers were prepared from solutions of PSSA-MA/PVA combined at ratios of 0.2/1 to 1/1; the fibers were subsequently crosslinked at 80–150 °C for 0.25–7 h. The effect of the crosslinking time, the temperature and the PSSA-MA/PVA ratio on various properties of the obtained ion-exchange fibers was investigated. When the PSSA-MA/PVA ratios were greater than 0.4/1, bead formation was observed. Thus, only smooth fibers without beads prepared from PSSA-MA/PVA mixed in ratios up to 0.4/1 were subjected to the thermal crosslinking treatment. When the crosslinking time and temperature were increased, the degree of crosslinking increased, which caused a decrease in the water solubilization and water uptake and an increase in the Young’s modulus. These parameters also appeared to significantly affect the ion-exchange capacity value. The temperature and time for successful crosslinking were 120–140 °C and 1–7 h, respectively.     

Effects of processing parameters on morphology of electrospun polystyrene nanofibers

This study focused on the preparation of electrospun polystyrene (PS) nanofibers. PS solutions were prepared in single (dimethylformamide; DMF, dimethylacetamide; DMAc or tetrahydrofuran; THF) and mixed solvent (DMF/THF and DMAc/THF) systems with and without tetrabutylammonium bromide (TBAB) salt. The effects of PS concentration, solvent system, the addition of salt, appearance and diameter of PS fibers were examined. The average diameter of the as-spun fibers increased upon increasing PS concentration. The morphology of the fibers significantly depended on the properties of the solvents. The obtained fibers were smooth without any beads and their diameters were affected by the amount of THF in the solvent and PS concentration. The beads in the fibers disappeared and the fiber diameter significantly decreased after the addition of TBAB. The smallest diameter and the narrowest diameter distribution of PS nanofibers (376±36 nm) were obtained from 15% PS solution in DMAc with 0.025% w/v TBAB.