Effects of Fe²⁺ ions on morphologies, microstructures and mechanical properties of electrospun nylon-6 nanofibers

In this study, nylon-6 nanofiber mats containing Fe²⁺ ions were fabricated via electrospinning. The resultant electrospun nylon-6/FeCl₂ nanofiber mats were characterized by SEM, TEM, Fourier transform IR spectroscopy, wide angle XRD and DSC. Unique morphological features, such as spider's-web-like morphologies, were observed and became evident with increasing additive Fe²⁺ ions. The metastable γ form was predominant in the as-spun nylon-6 nanofibers. The relative intensity of such γ form gradually decreased with increasing additive Fe²⁺ ions, indicative of transformation of the crystalline structure in the electrospun nylon-6/FeCl₂ nanofibers due to strong molecular interactions between the nylon-6 backbone and the additive Fe²⁺ ions. The effects of additive Fe²⁺ ions on the mechanical properties of both nonwoven nanofiber mats and single nanofibers were investigated. In particular, Young's modulus of nylon-6/FeCl₂ single nanofibers gradually increased from 1.46 to 5.26 GPa with increasing additive Fe²⁺ ions.