Whipping instability

Till date two important modeling zones have been introduced. These zones are (a) The zone close to the capillary (jet initiation zone) outlet of the jet and (b) The whipping instability zone where the jet spirals and accelerates towards the collector plate [11,24, 27]. 

The interplay of these different forces (a simple expression is the sum of these forces) determines the diameter of the jet. Some of these change very rapidly in time due to solvent evaporation and charge dissipation, making any quantitative description of the process particularly difficult. Consequently, no entirely satisfactory mathematical models describing jets undergoing whipping instability are available. 

Figure 1.9 Complicated trajectories of the Jet in the whipping instability region during the electrospinning of PCL in 15 wt% acetone solution (applied voltage is 5 kV and gap distance is 14 cm). Reprinted with permission from Reneker et al. (2002). Copyright 2002. Elsevier.

Figure 3.12 Basic electrode arrangement in electrospinning. Reprirrted with permission from Y. M. Shin et al. (2001b). Copyright 2001. Elsevier. The shaded area represents the whipping instability region.

FIGURE 23.2 Instabilities in the jet (a) Rayleigh instability (b) axisymmetric conducting instability (c) bending instability (d) whipping instability. 

---