Microstructural Characterization of Aligned PAN Nanofibers Collected by Hot Air Flow in Electrospinning Method

Amodified technique is designed to prepare aligned nanofibers to challenge the existing limitations in collecting methods of nanofibers such as, thickness of collected layer, alignment and productivity of nanofibers. Collecting and simultaneously heating of the aligned nanofibers were carried out by using a rotating drum fixed on top of syringe needles and applying hot air flow. This electrospinning set up can facilitate heating of thenanofiber in electrospinning zone (distance between two syringe needles). Polyacrylonitrile (PAN) nanofibers were electrospun from its 14 wt% solutio in dimethylformamide (DMF) under practical conditions. The above method resulted in low rupture rates and increased maximum take up speed for two collections. The obtained results from angular power spectrum analysis showed better fiber alignment with increasing take up speed, although SEM studies demonstrated wider diameters of nanofibers being produced by the modified method. The glass transition temperature (Tg) of all the prepared samples were between 70oC and 90oC. The recorded spectra from FTIR were close to common PAN fibers with peaks at 2240 cm-1 (CN stretch),2920 cm-1 (CH2 bend), 1450 cm-1 (CH stretch) and 1730 cm-1 (CO stretch) wavenumbers. The diffraction patterns obtained from WAXD technique show also an equatorial peak in 2θ = 17o for PAN nanofibers. Our quantitative analysis of WAXD and FTIR diagrams have revealed positive effects by the modified method on crystallization degree of nanofibers produced at higher take up speeds.