The relevance of extensional rheology on electrospinning: the polyamide/iron chloride case

Abstract

The outcomes of the electrospinning of polyamide 6 (PA6) solutions in formic acid containing FeCl3 are correlated with the extensional rheological behaviour of these fluids, which is investigated by the self-controlled capillary breakup of a filament. The rheological analysis enlightens a significant effect of the FeCl3 content on the rheological behaviour, the viscous component becoming predominant over a certain salt content threshold. At this concentration, the electrospun fibres show the formation of severely inhomogeneous structures this indicating that an elastically dominated behaviour is necessary to yield defect-free fibres. Addition of FeCl3 also decreases fibre crystallinity and fibres turn out to be completely amorphous above a critical concentration. Interestingly, this concentration coincides with the one at which the viscous component starts dominating the rheological behaviour.

Needleless Electrospinning of PA6 Fibers: The Effect of Solution Concentration and Electrospinning Voltage on Fiber Diameter

“…In the measured range of shear rates, up to 150 1/s all materials exhibited Newtonian behavior. Within the measured shear rates, we did not observe shear thinning behavior, which is in line with findings in [28]. For the analysis, the viscosity was calculated as the average viscosity value in the measured shear rate range.…”

Electrohydrodynamic Processing of PVP-Doped Kraft Lignin Micro- and Nano-Structures and Application of Electrospun Nanofiber Templates to Produce Oleogels

“…For pure Newtonian fluids, the Trouton ratio should theoretically be equal to 3 and significantly higher for viscoelastic liquids [ 64 , 65 ]. As can be seen in Figure 4 B, this theoretical value was accomplished in all cases at short times, and then Trouton ratio significantly increases over time, especially for the more concentrated solutions and for the lower EKL:PVP ratios, reaching values up to 80–90.…”

Tailoring the Diameters of Electro-Mechanically Spun Fibers by Controlling Their Deborah Numbers

“…The effect of the velocity of deposition and polymer concentration has been analyzed for NFES with opposite results than the ones reported in this work [ 2 , 14 , 27 , 29 ]. However, their experiments also differ in the experimental conditions, while using longer distances from tip-to-collector, higher voltages, concentrations, and velocities of deposition, see Table 1 .…”

“…Process variables, such as flow rate, applied voltage, distance from tip to the collector, velocities of pattern fabrication, the conductivity of the solution, and others, have been studied in order to produce high-quality fibers [ 7 , 12 , 13 ]. Other aspects affecting the final diameter and morphology of fibers are the rheological properties of the polymer solution, which have been widely studied for FFES [ 14 , 15 , 16 , 17 , 18 ]. Although the literature regarding LVNFES and NFES has presented rheological data, none of these have combined the De with the process parameters in order to control the final morphology of the fibers [ 2 , 19 ].…”