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Investigation of Buckling Phenomenon in Fiber Production Using Direct Electrospinning

Etesami, Zahra | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43549 (04)
  4. University: Sharif University of Technology
  5. Department: Physics Science
  6. Advisor(s): Iraji Zad, Azam
  7. Abstract:
  8. Duringfalling a viscous liquid freely on a surface, the viscous thread bends due to a phenomenon called buckling. The gravity force in this process could be replaced by an electric force in electrospinning process. In the present thesis, we have designed a number of setups in order to investigate the buckling phenomenon in two categories of helical and non-helical buckling by using direct electrospinning process. By making the collector moving, the electrospun fibers show several shapes including coiling, meander, figure of 8 shape, etc. There are three effective forces acting in this process which are viscous force, electric force and inertia. Also there are three distinct regimes defined by the power ratio of those three forces. In helical buckling, theoretical and experimental investigations on the buckling frequency have been done in the inertial regime in which, the inertial and viscous forces are blanced and the electric force could be neglected in comparison with two other ones. In the present thesis, buckling frequency in electric and inertio-electrical regimes has been studied and experiment data for buckling frequency has been compared with theory. In inertio-electrical regime the main feature that is discontinuity in the buckling frequency has been demonstrated in a global diagram known for this frequency. For electric regime, theory shows that the frequency is proportional to UV2/3/d . It has been shown that the fitted data is a function of UV2/3/d with power of 1.02 with an error of ±0.05. Finally, we have plotted a phase diagram for the observed shapes in non-helical buckling and the ratio between main forces in which, these shapes become observable.

  9. Keywords:
  10. Buckling ; Phase Diagram ; Direct Elecrospinning ; Nonhelical Buckling ; Helical Buckling

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