Electrospinning Taylor cone

Yarin, A.L., Koombhongse, S., and Reneker. D.H., 2001b, Taylor cone and jetting from liquid droplets in electrospinning of nanofibers, J. Appl. Phys.. 9(90), pp. 4836-4845. 

Figure 4.2 Schematic illustration of the conventional set-up for electrospinning. The insets show a drawing of the electrified Taylor cone, bending instability, and a typical SEM Image of the nonwoven mat of PET nanofibers deposited on the collector. The bending Instability Is a transversal vibration of the electrospinning jet. It is enhanced by electrostatic repulsion and suppressed by surface tension...

Electrospinning uses a high-voltage electrical field (typically 10-20 kV) to form micro- and even nanoscale fibres from a suspended droplet of polymer melt or solution [118]. When the repulsive electrostatic interactions overcome the droplet s surface tension, a Taylor cone is formed and a polymer jet is ejected from the tip of this Taylor cone [119]. The polymer jet is then accelerated towards a grounded collector screen. As the jet moves through the air, a stretching process occurs and the solvent evaporates which results in a non-woven polymer fabric or polymer mat [120]. Electrospinning has already been applied for both synthetic as well... 

The flow rate will determine the amount of solution which will be used for electrospinning. For a certain voltage, there is a corresponding flow rate which maintains the stability of Taylor cone. If the flow rate is increased, there will be a corresponding increase in the fiber diameter or bead size. This is apparent as there... 

A coaxial setup uses a multiple solution feed system that allows for the injection of one solution into another at the tip ofthe spinneret. The sheath fluid act as a carrier drawing in the inner fluid at the Taylor cone ofthe electrospinning jet. If the solutions are immiscible then a core-shell structure is usually observed. Miscible solutions, however, can result in porosity or a fiber with distinct phases due to phase separation during solidification ofthe fiber. 

The electrostatic forces generated by the high electrostatic field can easily interact with electrically conductive liquids. In the case of classical electrospinning a droplet of solution is applied. If the interaction is adequate, the droplet forms a conical shape. This shape is called Taylor cone in honor of Taylor [59] who achieved significant results in the mathematical description of liquid surface formation. 

Figure 10.6. Electrospinning - formation of Taylor cones and jets from the tips...

Figure 10.32. Coaxial electrospinning basic setup and the formation of Taylor cone [64]...

Analogous to HME, electrospinning is also a widely used technique in the polymer industry. A schematic of electrospinning process is shown in Fig. 3.11. A polymer solution is drawn through a capillary tube that is subjected to an electric field. As the electric field increases, the feed solution forms a Taylor cone at the tip of the capillary. Once the electric field overcomes the surface tension of the solution, the polymer solution is ejected as an electrically charged jet. Due to the increase in surface area, the solvent evaporates leaving thin filaments of material (50 nm to 5 microns). These fibers are then collected on collector screens for further processing. This technique has been applied for pharmaceutical systems by several researchers... 

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