Electrospinning capillary tips

The morphologieal struetme ean be slightly changed by changing the solution flow rate as shown in Figure 12. At the flow rate of 0.3 ml/h, a few of big beads were observed on the fibers. The flow rate eould affect electrospinning process. When the flow rate exceeded a critical value, the delivery rate of the solution jet to the capillary tip exceeded the rate at which the solution was removed from the tip by the electric forces. This shift in the mass-balanee resulted in sustained but rmstable jet and fibers with big beads were formed [56]. 

Figure 3.9 An electrospinning jet of 4% solution of PHBV in chloroform imaged at different distances from the tip showing the development of axisymmetric instabilities (applied voltage 20 kV and feed rate 4 mL/h). Images (a) through (h) correspond to distances of 1, 3, 5, 7, 9, 12, 15, and 30 cm from the capillary tip. Reprinted with permission from Zuo et al. (2005). Copyright 2005. John Wiley Sons.

TABLE 4.4 The effect of capillary tip orifice size on electrospinning of (lactide-co-e-caprolactone) copolymer... 

The needle or tube that delivers the polymer solution in elecbospinning is also referred to as the spinneret , tip or nozzle in the electrospinning literature. We prefer to use the term capillary tip or tip in this work. 

Figure 6.12 Arrangement of capillary tips for concurrent electrospinning and electrospraying to obtain nanofibers decorated with nanoparticles. (Courtesy of RTI International.)...

A similar technique was used by Min et al. (2004d) to electrospin copolymers of lactide with glycolide (PLGA) nanofibers from hexafluoroisopropa-nol (HFP) solvent from one capillary tip and regenerated chitin in formic acid electrosprayed from a separate tip, onto the same grounded collector drum. In this case, however, both electrospinning solutions carried a positive charge. 

Figure 9.5 (a) The coaxial double-capillary tip arrangement used in electrospinning core-shell nanofibers. Reprinted with permission from Sun et al. (2003). Copyright 2003. John Wiley Sons, (b) A coaxial tip design used by Larsen et al. (2003) for olive oil-water (liquid-liquid) coaxial jets. The inset shows the double-layered Taylor s cone. Reprinted with permission from Larsen et al. (2003). Copyright 2003. American Chemical Society. 

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