Effect of Processing Parameters on the Diameter and Morphology of Electrospun Iron-Modified Montmorillonite (Fe-MMT)/Polycaprolactone Nanofibers

Abstract

Iron-modified montmorillonite-filled polycaprolactone nanofiber mats were produced via electrospinning with varying applied voltage, flow rate, needle-tip-to-collector distance, and needle diameter. Scanning electron microscopy (SEM) was used to observe fiber morphology and characteristics. The effects of varying process parameters on various fiber characteristics were evaluated using a two-level fractional factorial experimental design. The effect of voltage on fiber diameter differed with varying flow rate. At 32 ml/hr, the average fiber diameter decreased from 518.38 nm ± 289.37 nm to 466.43 nm ± 312.36 nm when the voltage is increased. At 42 ml/hr the effect of voltage on fiber diameter was reversed. The average fiber diameter was also found to decrease from 516.03 nm ± 283.48 nm to 467.96 nm ± 318.07 nm with decreasing tip-to-collector distance at 32 mL/hr flow rate. The variation of the effect of the factors on fiber diameter was mainly due to a significant loss of material observed at 12 kV and 15 cm tip-to-collector distance. Bead formation was observed for all runs with more beads being formed at 12 kV applied voltage and 15 cm tip-to-collector distance. Spherical beads were observed at 12 kV and 15 cm tip-to-collector distance while spindle-like beads were present in nanofiber membranes spun at high voltage and at the combination of low voltage and low tip-to-collector distance. The parameter setting combination of 19 kV, 32 ml/hr flow rate, 10 cm tip-to-collector distance, and 0.514 mm needle diameter yielded the lowest fiber diameter with the least amount of beading and small bead size. Small fiber diameters and less beading provide larger surface area and more exposure of the Fe-MMT particles for more efficient adsorption.