Microstructure of heat-treated PAN nanofibers

A simple and modified electrospinning technique was utilized to prepare aligned and heat treated Polyacrylonitrile nanofibers by using a rotating drum fixed on top of syringe needles and applying upward hot air flow which can facilitate to heat nanofibers in electrospinning zone. Polyacrylonitrile nanofibers were electrospun from its 14 wt% solution in dimethylformamide under practical conditions. Angular power spectrum analysis showed better fiber alignment with increasing take up speed, although SEM studies demonstrated wider diameters of nanofibers being produced by modified method. The glass transition temperature of all prepared samples were determined between 70 °C and 90 °C using DSC technique. The Quantitative analysis of WAXD patterns has revealed the positive effect of modified method on the degree of crystallization of nanofibers heat treated at higher take up speed. The maximum chain orientation factor of 0.27 was determined for nanofibers collected at linear velocity of 114.5 m/min in the modified set up using Raman Spectroscopy technique.