Effect of needle length, electrospinning distance, and solution concentration on morphological properties of polyamide-6 electrospun nanowebs

Nowadays, thanks to the electrospinning process, polymeric fibers in nanoscale diameters (10-500nm) are easily producible. During the last decade, the electrospinning technique has been greatly investigated and developed. One of the most important fields of study on the electrospinning process is the influence of effective parameters on electrospun nanofibers and nanoweb properties. In this study, using polyamide-6 (PA-6)/formic acid polymer solution, three important parameters of the electrospinning process, including polymer solution concentration, needle-tip-to-collector distance, and needle length, were precisely studied. The solution concentration is a very important parameter that affects the nanowebs' homogeneity and nanofibers' diameter evenness. Scanning electron microscopy (SEM) analysis of the electrospun nanowebs showed that among five polymer solution concentrations (5, 10, 15, 20, and 25wt%), 25wt% was more suitable and provided the homogeneity and reproducibility of PA-6 nanowebs. It has been found that the needle-tip-to-collector distance had a considerable influence on the nanofibers' diameter and the nanoweb collection zone. Morphological investigation and statistical studies showed that the nanofibers' diameter increased with the reduction of the needle-tip-to-collector distance. Moreover, the average diameter of the nanoweb collection zone decreased by the reduction of this distance. The effect of needle length on the nanofibers' morphology and nanowebs' collection zone was investigated. Statistical analysis of the obtained results revealed that the increase of needle length significantly increased the average nanofibers' diameter. Inversely, the diameter of the nanoweb collection zone reduced when needle length increased. All previously mentioned studies helped to define the optimal electrospinning condition to produce the bead-free, non-branched, and homogeneous PA-6 electrospun nanofibers and nanowebs.