Systematic optimization and characterization of electrospun polyacrylonitrile/multi-walled carbon nanotube nanocomposite fibers using Taguchi robust design

This study reports the fabrication and systematic optimization of polyacrylonitrile (PAN) nanocomposites reinforced with multi-walled carbon nanotubes (MWCNTs) via the electrospinning process. The research focused on analyzing fiber diameter using Design Expert software and the Taguchi methodology, due to the advantageous properties associated with electrospun fibers of smaller diameters. Nine experiments were designed to investigate the effects of key parameters (solution concentration, applied voltage, and tip-to-collector distance) on the average fiber diameter. Scanning electron microscopy (SEM) was used to analyze the fibers, and ImageJ software was employed to measure their diameters from the SEM images. The results showed that among the various parameters studied, only the polymer concentration significantly influenced the fiber diameter. In contrast, the effects of applied voltage and electrospinning distance were negligible. Increasing the solution concentration led to the formation of uniform, bead-free fibers, albeit with larger average diameters. Based on morphological analysis, the optimal processing conditions were identified as 12% (w/v) solution concentration, 22 kV applied voltage, and a 22 cm distance from the needle to the rotating drum collector. Subsequently, MWCNTs were incorporated into the 12% (w/v) PAN solution at four different weight fractions: 0.25, 0.50, 1, and 2%. SEM imaging demonstrated that fiber composites maintained appropriate and defect-free morphology up to 2 wt% MWCNT loading. Fourier-transform infrared spectroscopy (FTIR) revealed no chemical interactions between the polymer and the carbon nanotubes. Furthermore, contact angle measurements indicated that the fiber composites exhibited lower contact angles compared to the pure PAN fibers, suggesting enhanced surface wettability. These findings highlight the potential of the optimized PAN/MWCNT nanofibers for applications requiring high surface area and hydrophilic fibrous materials, such as high-performance filtration membranes, tissue engineering scaffolds, and sensor platform.