1. Physical principles of nanofiber production 1
Physical principles of nanofiber production 1. Needle-less electrospinning
D. Lukáš
2010

2. 3.6. Self-organisation of electrospinning jets on free liquid surfaces

3. Needle electrospinning:
Self-organisation of the fluid in electrospinning is the underlying cause behind formation of the Taylor cone, the stable jet part, the whipping zone and evaporation of solvent.
Now, it will be shown that the self-organising potential of electrospinning is even more forcerful since it has a power to organize :
individual jets on free liquid surfaces without any need to use needless / capillaries to create them.
This finding is enormously attractive regarding the recent effort to elevate electrospinning technology to industrial level because it opens a chance to design simple as well as highly productive lines for nanofibrous layer production.

4. A rode instead of a needle E = Ec+ + + + + + + + + + + + +
Stationary wave
d=1cm 1 2 3 4
Epoxy resin E Ec
F. Sanetrník
no.
Sandra Torres 5 6

5. Angular frequency Growth factor
Dynamic phenomenon: field strength increment can lead to unlimited growth of a wave amplitude.
A. Sarkar
Wave vector
Amplitude
Angular frequency Growth factor

6. Electrospinning - X-rays
Stable amplitude
Growing amplitude
Dispersion law
Lukas D Sarkar A Pokorny P, Self organization of jets in electrospinning from free liquid surface - a generalized approach, accepted for publication, Journal of Applied Physics, 103 (2008),
Clemson University
Electrospinning - X-rays

7. D. Lukas, A. Sarkar, and P. Pokorny, Journal of Applied Physics, 103 (2008)

8. Euler equation Elektrostatic forces gravitation Surface tension
Velocity potential
gravitation
Elektrostatic forces
Surface tension
Equation of continuity
dispersion law
Needleless Electrospinning
Prague 2007

9. Electrospinning - X-rays
Tonks-Frenkel instability E
Various field strengths E
Stable waves of various wave numbers and angular frequencies.
Fastest forming instability
The only wave
Clemson University
Electrospinning - X-rays

10. Capillary waves
Electrospinning
Relaxation time
Growth factor

11. Critical field strength
Quadratic equation with the only solution
Critical field strength

12. capillary length

13. Dimensionless electrospinning number

14. Minimal and negative square values of the angular frequency correspond to the maximal growth factors, q’s, inherently connected with the self-organisation caused by the mechanism of the fastest forming instability. +

15. dimensionless intra-jet distance

16. Electrospinning - X-rays
Clemson University
Electrospinning - X-rays

17. Electrospinning - X-raysb
32 kV
43 kV
Linear clefts emit polymeric jets. Linear clefts in (a) and (b) emit polymeric (polyvinyl alcohol) jets at the voltages, 32 kV and 43 kV, respectively. The inter-jet distance / wavelength is l. The distance between the cleft and the collector was adjusted on 802 mm.
Clemson University
Electrospinning - X-rays

18. Electrospinning - X-rays
Technology
Jirsák, O. Sanetrník, F. Lukáš, D. Kotek, V. Marinová, L. Chaloupek, J. (2005) WO A Method of Nanofibres Production from A Polymer Solution Using Electrostatic Spinning and A Device for Carrying out The Method.
Clemson University
Electrospinning - X-rays