Ultrafine Electrospun Polyamide‐6 Fibers: Effects of Solvent System and Emitting Electrode Polarity on Morphology and Average Fiber Diameter

Abstract

Abstract Summary: In the present contribution, polyamide‐6 (PA‐6) solutions were prepared in various pure and mixed‐solvent systems and later electrospun with the polarity of the emitting electrode being either positive or negative. The PA‐6 concentration in the as‐prepared solutions was fixed at 32% w/v. Some of the solution properties, i.e., shear viscosity, surface tension, and conductivity, were measured. Irrespective of the polarity of the emitting electrode, only the electrospinning of PA‐6 solution in formic acid (85 wt.‐% aqueous solution) produced uniform electrospun fibers, while solutions of PA‐6 in m ‐cresol or sulfuric acid (either 20 or 40 wt.‐% aqueous solution) did not. In the mixed‐solvent systems, formic acid (85 wt.‐% aqueous solution) was blended with m ‐cresol, sulfuric acid (either 20 or 40 wt.‐% aqueous solution), acetic acid, or ethanol in the compositional range of 10–40 vol.‐% (based on the amount of the minor solvent). Generally, the average fiber diameter increased with increasing amount of the minor solvent or liquid. Interestingly, the diameters of the fibers obtained under the negative electrode polarity were larger than those obtained under the positive one. Optical images of electrospun fibers from solutions of polyamide‐6 in a mixed solvent of 85 wt.‐% formic acid and 20 vol.‐% m ‐cresol under positive (left) and negative (right) electrode polarity. magnified image Optical images of electrospun fibers from solutions of polyamide‐6 in a mixed solvent of 85 wt.‐% formic acid and 20 vol.‐% m ‐cresol under positive (left) and negative (right) electrode polarity.