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

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

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D. Luk 2010 Physical principles of nanofiber production 1. Needle-less electrospinning 1 Slide 2 3.6. Self-organisation of electrospinning jets on free liquid surfaces 2 Slide 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. 3 Slide 4 4 Epoxy resin E no. 1234 6 1 2 3 4 5 6 E = 0 E = E c EcEcEcEc A rode instead of a needle 5 d=1cm + + + + + + +++ + +++ Stationary wave F. Sanetrnk Sandra Torres Slide 5 5 Wave vector Angular frequency Growth factor Dynamic phenomenon: field strength increment can lead to unlimited growth of a wave amplitude. A. Sarkar Amplitude Slide 6 Clemson UniversityElectrospinning - X-rays6 Stable amplitude Growing amplitude Lukas D Sarkar A Pokorny P, S ELF ORGANIZATION OF JETS IN ELECTROSPINNING FROM FREE LIQUID SURFACE - A GENERALIZED APPROACH, ACCEPTED FOR PUBLICATION, Journal of Applied Physics, 103 (2008), 309-316. Dispersion law Slide 7 D. Lukas, A. Sarkar, and P. Pokorny, Journal of Applied Physics, 103 (2008) 7 Slide 8 Needleless ElectrospinningPrague 20078 Euler equation gravitation Surface tension Elektrostatic forces dispersion law Velocity potential Equation of continuity Slide 9 Clemson UniversityElectrospinning - X-rays9 Stable waves of various wave numbers and angular frequencies. Fastest forming instability The only wave Various field strengths E E Tonks-Frenkel instability Slide 10 Capillary waves Electrospinning Relaxation time Growth factor 10 Slide 11 11 Quadratic equation with the only solution Critical field strength Slide 12 12 capillary length Slide 13 13 Dimensionless electrospinning number Slide 14 14 Minimal and negative square values of the angular frequency correspond to the maximal growth factors, qs, inherently connected with the self-organisation caused by the mechanism of the fastest forming instability. + Slide 15 15 dimensionless intra-jet distance Slide 16 Clemson UniversityElectrospinning - X-rays16 Slide 17 Clemson UniversityElectrospinning - X-rays17 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. The distance between the cleft and the collector was adjusted on 802 mm. b 32 kV43 kV Slide 18 Clemson UniversityElectrospinning - X-rays18 Technology Jirsk, O. Sanetrnk, F. Luk, D. Kotek, V. Marinov, L. Chaloupek, J. (2005) WO2005024101 A Method of Nanofibres Production from A Polymer Solution Using Electrostatic Spinning and A Device for Carrying out The Method. www.elmarco.com