Experimental Characterization of electrospinning: the electrically forced jet and instabilities
Original Entry by Holly McIlwee, AP225 Fall 09
Experimental Characterization of electrospinning: the electrically forced jet and instabilities. Y. M. Shin, M. Hohman, M. P. Brenner and G. C. Rutledge, Polymer, 42,9955-9967(2001).
Electrospinning, Electrified Fluid Jet, Instability
Sub micron polymer fibers are formed from solution by subjecting the solution to a high electric field. The author has chosen to investigate the jet of polymer that is produced by this electric field and its instabilities.
Traditionally polymer fibers are formed using a technique called extrusion which applies pressure on a polymer melt to great a continuous fiber or profile. The extrusion process is not optimized for sub-micron features without many defects or mechanical instabilities. In order to form sub-micron fibers, the electrospinning process has been employed more recently. The attractiveness of these fibers stems from their high surface area to volume ratio. The first reference to the electrospinning process was in 1934.  But more recently in 1995,  it was confirmed that submicron fibers were formed.
As of 2001 over 30 polymers had been electrospun. Material, equipment, and operating parameters can have a great effect on the resulting fibers and up until the time of this paper, many of these issues were not extensively studied. Until this time there has not been a quantitatively accurate theory, which Brenner et al. believes in a hinderance to comparing and analyzing results. Brenner sets out to show that jet formation and instability can be characterized by using a small set of operating parameters.
It was found that the shape of the jet is dependent on the E-field and flow rate. When the electric field in increased the jet thins more rapidly and th Taylor cone becomes shorter and more concave
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