Three Dimensional Instability of Polymer Jet in Electrospinning
Date Issued
2011
Date
2011
Author(s)
Huang, Tang-Hsuan
Abstract
Nanofibers are one of important nano-materials with good mechanical properties and wide applications in the catalyst and optoelectronic industries. Among various methods, Electrospinning is the only one that can produce continuous and uniform nanofibers. However, this technology is still developing because the process involves complex motion, affected by interaction between electric stress, viscoelastic force, and surface tension. In general, good morphology of nanofibers is unobtainable if the operating conditions are not appropriately chosen. A complete understanding of physical mechanisms is thus necessary for the improvement of the technique.
So far, the theoretical study is still focused on the linear instability analysis because a complete analysis must include the nonlinear coupling between the rheological constitutive laws and Maxwell equation. Even so, the linear analysis can provide preliminary understanding of instability mechanisms. Previous works have revealed that the various undesirable morphologies (ex. bead-on-strings, branch) are actually resulted from the growth of nonaxisymmetric disturbances during the jetting process. However, the results are obtained by neglecting either the axial electrical field or the unrelaxed viscoelastic tension, which has caused quantitative disagreement when compared with experimental measurements.
This paper aims to improve the existing mathematical model by taking both the effects of the axial electrical field and the viscoelastic tension into account. By this analysis, a deeper insight into the physical mechanisms during electrospinning process will be provided to qualitatively explain the formation of various microstructures of nanofibers.
Subjects
Electrospinning
Nanofibers
Polymer
Vicoelastic fluid
Insatability
Electrohydrodynamics
Type
thesis
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