Nonafiber Membrane of EVOH-Based Ionomer by Electrospinning

Electrospinning is a straightforward and effective technique to produce nanofiber nonwovens. In this paper, a comb ionomer of poly(ethylene covinyl alcohol) end-capped with sulfonic acid (EVOH-g-SO ₃H) was synthesized by two-step synthesis process and electrospun into nonwoven membranes. The effect of processing parameters on the fibrous and beads morphology was investigated by scanning electron microscopy (SEM). The result indicated that the morphology of EVOH-g-SO₃H membrane was heavily dependent on the electrospinning process as the electrospinning voltage (v), the concentration of polymer solution (c), the surface tension of polymer solution (sigma), the solution flow-rate (upsi), and the deposition distance between the syringe needle and the collecting drum (1). A ´beads-on-string´ morphology could be seen from SEM image when the solution was electrospun in DMAc/water while decreasing the surface tension is a good way towards the formation of fibers without beads. When the solution concentration reaches 35wt%, a melded twist-ribbon structure could appear. There is an optimum range of solution concentration (5.0~20.0wt%) for a stable electrospinning and nonwoven formation. A higher applied voltage could result in a higher electric charge density on the surface of polymer solution jet during the electrospinning, they cause the higher splitting to the polymer jet and result in higher density and smaller diameter of round beads, as well as they also produce the thinner diameters fibers