The effect of a self-pulsing non-equilibrium plasma discharge on piezoelectric PVDF nanofiber membrane was investigated. The plasma discharge was generated in air with a DC power source, with a discharge current of 0.012 mA, a nominal interelectrode separation of 1 mm, and discharge voltage of ~970 V. In a continuous fabrication process, the electrospinning method was used to generate thin nanofiber membrane with a flow rate of 0.7–1 mL h⁻¹ and 25–27 kV voltage to obtain the nanofiber with high sensitivity and a higher degree of alignment and uniformity over a larger area. Plasma treatment was applied on both single layer and multi-layer (three layers) nanomembranes. In addition, simultaneously, the nanofiber membranes were heat-treated at a glass transition temperature (80–120 °C) and then underwent plasma treatment. Fourier-transform infrared (FTIR) spectroscopy showed that the area under the curve at 840 and 1272 cm⁻¹ (β phase) increased due to the application of plasma and differential scanning calorimeter (DSC) indicated an increase in the degree of crystallinity. Finally, PVDF sensors were fabricated from the nanofibers and their piezoelectric properties were characterized. The results suggested that compared to the pristine samples the piezoelectric properties in the plasma and plasma-heat-treated sensors were enhanced by 70% and 85% respectively.

Cellulose acetate (CA) fibers were reinforced with multi-walled carbon nanotubes (MWCNTs) at 0.5%, 1.0%, 1.5% and 2.0%. Yield strength, ultimate tensile strength, fracture strain and toughness of the nanocomposite fiber increased up to 1.5 wt. % of the carbon nanotube (CNT) loading, however, further inclusion (2.0%) of MWCNTs in CA decreased the mechanical properties. Experimental properties were also compared with analytical predictions using a Shear lag model for strength and the rule of mixture for modulus. A solution spinning process, coupled with sonication, mixing, and extrusion, was used to process the CNT-reinforced composite fiber. Scanning electron microscopy (SEM) images of the cross sections of neat CA and CA-MWCNT fibers showed the formation of voids and irregular features. The enhanced interconnected fibrillation in the CNT-reinforced CA samples resulted in improved mechanical properties, which were observed by tensile testing. Fourier transform infrared spectroscopy (FTIR) spectra showed the area under the curve for C–H bonding after the inclusion of CNT. There was no significant shift of wavenumber for the inclusion of MWCNT in the CA matrix, which indicates that the sonication process of the CNT-loaded solution did not degrade the CA bonding structure.

This study reports the fabrication of corona treated hybrid nanocomposite fibers by blending Polyacrylonitrile (PAN), Polyvinylidene fluoride (PVDF), and single-walled carbon nanotubes (SWCNT) in a solution spinning process. Plasma treated nanocomposite textile fiber offers the possibility of better morphological and piezoelectric property by shifting PVDF crystalline phase from ë± to ë_. Plasma application setup consists of a high voltage power supply, a ballast resistor, anode and cathode. Corona and normal glow plasma were generated by altering voltage, current and the distance between anode and cathode. A lab-scale solution spinning line consists of a constant torque gear pump and heated extrusion channels was used to produce the fibers. Both neat and CNT-loaded PAN-PVDF fibers were produced. The PVDF and CNT loading with respect to base polymer PAN were 2wt% and 7wt% respectively where DMF was used as solvent. The as-produced viscous gel-like solution was pumped through a spinneret to a coagulation bath. After the formation of fibers, plasma was applied immediately and the fibers were collected to a takeup roll at a draw ratio of 1:5. This study also investigate the effect of PVDF and CNT loading on a PAN fiber to improve crystallinity and thermal stability. The prepared fibers are characterized by differential scanning calorimetry (DSC), scanning electronic microscopy (SEM), and thermogravimetric analysis (TGA). Differential Scanning Calorimetry (DSC) study shows increased crystallinity in the hybrid fibers due to the inclusion of 7 wt% PVDF. A significant improvement in thermal stability of PAN-PVDF-SWCNT fibers compared to neat fibers are also observed in TG study. Scanning Electron Microscopy (SEM) shows the formation of micro-hollow and irregular features in the cross section in the nanocomposite fibers. Longitudinal views of outer surface of both neat PAN and PAN/PVDF/SWCNT fibers showed no indication of surface defects or protrusions. Tensile testing of corona treated fibers will be performed to determine the mechanical properties. And an impact test rig will be performed to observe the generation of voltage upon application of an impact load using a digital oscilloscope. Fourier Transform Infrared Spectroscopy (FTIR) will be done on fibers to analyze the effect of corona application.