Scaling Laws in Electrospinning of Polystyrene Solutions
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- 作者：Chi Wang ; Chia-Hung Hsu ; Jian-Hua Lin
- 刊名：Macromolecules
- 出版年：2006
- 出版时间：October 31, 2006
- 年：2006
- 卷：39
- 期：22
- 页码：7662 - 7672
- 全文大小：320K
- 年卷期：v.39,no.22(October 31, 2006)
- ISSN：1520-5835
文摘
By tuning the processing variables and solution properties using four different solvents(dimethylformamide, o-dichlorobeneze, tetrahydrofuran, and chloroform), polystyrene (PS) fibers were preparedby the electrospinning process to study the effects of these governing parameters on the morphological changesof the charged cone and jet, as well as the diameter and birefringence of the fibers collected. Both jet diameter(dj) and fiber diameter (df) were scaled with the processing variables, i.e., solution flow-rate (Q), applied voltage(V) and working distance (H), with a power law model. Knowledge of these exponents provided insight into howto manipulate the electrified jet and spun fibers for a given solution. Results showed that Q was the dominantfactor in determining the fiber diameter and the Q dependences of dj and df were approximately scaled with: dj~ Q0.5 and df ~ Q0.25. The applied electric field (V/H) did affect the cone volume and the length of the electrifiedjet. Either increasing V or decreasing H produced a slightly thinner jet and smaller fiber, but the effects were notsignificant due to the limited processing range available for the stable cone-jet mode, and the nonuniformity ofthe electric field resulting from the point-to-plate electrode configuration used in this study. Regardless of thevariations of the processing variables (Q, V, and H), a master curve between dj and df was found for a solutionwith fixed properties, from which a simple equation was obtained and expressed by: df ~ mdj0.45 where m wasa prefactor depending upon solution properties, such as the viscosity (
), conductivity (
) and surface tension.Values of m were found to be lower for solutions with lower viscosity and/or higher conductivity, and weresuccessfully scaled to be as follows: m ~ o0.38-0.12. As far as the solution properties were concerned, theconcentration emerged as the most important parameter because of its interaction with all aspects of theelectrospinning process. The rheological properties of the polymer solution showed a significant effect on theformation of smooth electrospun fibers. On the basis of the Graessley's concentration-molecular weight diagram,various PS fiber morphologies were discussed and the minimum polymer concentration at a given polymermolecular weight required for preparing smooth PS fibers could be estimated. For the present PS solutions, ascaling law was found between the fiber diameter and solution viscosity: df ~ o0.41, if other governing parameters(Q, V, H, , and surface tension) were fixed.
), conductivity () and surface tension.Values of m were found to be lower for solutions with lower viscosity and/or higher conductivity, and weresuccessfully scaled to be as follows: m ~ o0.38-0.12. As far as the solution properties were concerned, theconcentration emerged as the most important parameter because of its interaction with all aspects of theelectrospinning process. The rheological properties of the polymer solution showed a significant effect on theformation of smooth electrospun fibers. On the basis of the Graessley's concentration-molecular weight diagram,various PS fiber morphologies were discussed and the minimum polymer concentration at a given polymermolecular weight required for preparing smooth PS fibers could be estimated. For the present PS solutions, ascaling law was found between the fiber diameter and solution viscosity: df ~ o0.41, if other governing parameters(Q, V, H, , and surface tension) were fixed.