Experimental investigation of the governing parameters in the electrospinning of polymer solutions
TL;DR: In this paper, the influence of different process parameters on the electric current and volume and surface charge density in the polymer jet was measured and the electric conductivity and permittivity were measured as well.
About: This article is published in Polymer.The article was published on 2004-03-01. It has received 954 citations till now. The article focuses on the topics: Electrospinning & Nanofiber.
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TL;DR: Electrospinning is a highly versatile method to process solutions or melts, mainly of polymers, into continuous fibers with diameters ranging from a few micrometers to a few nanometers, applicable to virtually every soluble or fusible polymer.
Abstract: Electrospinning is a highly versatile method to process solutions or melts, mainly of polymers, into continuous fibers with diameters ranging from a few micrometers to a few nanometers. This technique is applicable to virtually every soluble or fusible polymer. The polymers can be chemically modified and can also be tailored with additives ranging from simple carbon-black particles to complex species such as enzymes, viruses, and bacteria. Electrospinning appears to be straightforward, but is a rather intricate process that depends on a multitude of molecular, process, and technical parameters. The method provides access to entirely new materials, which may have complex chemical structures. Electrospinning is not only a focus of intense academic investigation; the technique is already being applied in many technological areas.
3,833 citations
TL;DR: A review of the literature on the various aspects of cellulosic fibres and biocomposites can be found in this paper, where the pros and cons of using these fibres are enumerated in this review.
1,908 citations
TL;DR: More studies are required to understand and precisely control the actual mechanics in the formation of various electrospun fibrous assemblies, which will enhance the performance of products made from nanofibres and allow application specific modifications.
Abstract: Although there are many methods of fabricating nanofibres, electrospinning is perhaps the most versatile process. Materials such as polymer, composites, ceramic and metal nanofibres have been fabricated using electrospinning directly or through post-spinning processes. However, what makes electrospinning different from other nanofibre fabrication processes is its ability to form various fibre assemblies. This will certainly enhance the performance of products made from nanofibres and allow application specific modifications. It is therefore vital for us to understand the various parameters and processes that allow us to fabricate the desired fibre assemblies. Fibre assemblies that can be fabricated include nonwoven fibre mesh, aligned fibre mesh, patterned fibre mesh, random three-dimensional structures and sub-micron spring and convoluted fibres. Nevertheless, more studies are required to understand and precisely control the actual mechanics in the formation of various electrospun fibrous assemblies.
1,808 citations
TL;DR: In this paper, the authors provide an overview of the electrospinning (applied electric field, distance between the needle and collector and flow rate, needle diameter), solution (polymer concentration, viscosity, solvent and solution conductivity) and environmental (relativity humidity and temperature) parameters that affect the nanofibers fabrication.
1,071 citations
Cites background from "Experimental investigation of the g..."
...This merging of nanofibers facilitates the formation of garlands (Reneker et al., 2002; Theron et al., 2004)....
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TL;DR: In this paper, a semi-empirical analysis of the transition from electrospraying to electrospinning in the good solvent, non-specific polymer-polymer interaction limit is presented.
1,058 citations
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TL;DR: In this article, the authors describe the electrospinning process, the processing conditions, fiber morphology, and some possible uses of electrospun fibers, and describe the diameter of these fibers in the range of 0.05 to 5 microns.
2,998 citations
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TL;DR: In this article, it was shown that a conical interface between two fluids can exist in equilibrium in an electric field, but only when the cone has a semi-vertical angle 49.3$^\circ$.
Abstract: The disintegration of drops in strong electric fields is believed to play an important part in the formation of thunderstorms, at least in those parts of them where no ice crystals are present. Zeleny showed experimentally that disintegration begins as a hydrodynamical instability, but his ideas about the mechanics of the situation rest on the implicit assumption that instability occurs when the internal pressure is the same as that outside the drop. It is shown that this assumption is false and that instability of an elongated drop would not occur unless a pressure difference existed. When this error is corrected it is found that a drop, elongated by an electric field, becomes unstable when its length is 1.9 times its equatorial diameter, and the calculated critical electric field agrees with laboratory experiments to within 1%. When the drop becomes unstable the ends develop obtuse-angled conical points from which axial jets are projected but the stability calculations give no indication of the mechanics of this process. It is shown theoretically that a conical interface between two fluids can exist in equilibrium in an electric field, but only when the cone has a semi-vertical angle 49.3$^\circ$. Apparatus was constructed for producing the necessary field, and photographs show that conical oil/water interfaces and soap films can be produced at the caloulated voltage and that their semi-vertical angles are very close to 49.3$^\circ$. The photographs give an indication of how the axial jets are produced but no complete analytical description of the process is attempted.
2,994 citations
"Experimental investigation of the g..." refers methods in this paper
...Taylor [6–9] produced useful experimental evidence on the conical shape of the protrusion from which a jet sometimes leaves the surface of a pendant liquid drop....
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TL;DR: In this paper, the authors analyzed and explained the reasons for the instability of a viscous jet of polymer solution at a pendent droplet, showing that the longitudinal stress caused by the external electric field acting on the charge carried by the jet stabilized the straight jet for some distance.
Abstract: Nanofibers of polymers were electrospun by creating an electrically charged jet of polymer solution at a pendent droplet. After the jet flowed away from the droplet in a nearly straight line, it bent into a complex path and other changes in shape occurred, during which electrical forces stretched and thinned it by very large ratios. After the solvent evaporated, birefringent nanofibers were left. In this article the reasons for the instability are analyzed and explained using a mathematical model. The rheological complexity of the polymer solution is included, which allows consideration of viscoelastic jets. It is shown that the longitudinal stress caused by the external electric field acting on the charge carried by the jet stabilized the straight jet for some distance. Then a lateral perturbation grew in response to the repulsive forces between adjacent elements of charge carried by the jet. The motion of segments of the jet grew rapidly into an electrically driven bending instability. The three-dimensional paths of continuous jets were calculated, both in the nearly straight region where the instability grew slowly and in the region where the bending dominated the path of the jet. The mathematical model provides a reasonable representation of the experimental data, particularly of the jet paths determined from high speed videographic observations.
2,324 citations
"Experimental investigation of the g..." refers background in this paper
...Electrospinning typically results in bending instability of the jet beginning at some distance from the droplet tip [1,2]....
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...In electrospun jets emitted from Taylor cones, bending instability develops due to the mutually repulsive forces resulting from the electric charges of the jets [1,2]....
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TL;DR: In this article, the equilibrium of liquid conducting masses charged with electricity was studied and the authors proposed a method to solve the problem of finding the equilibrium point of a liquid conducting mass with respect to electricity.
Abstract: (1882). XX. On the equilibrium of liquid conducting masses charged with electricity. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science: Vol. 14, No. 87, pp. 184-186.
1,503 citations
TL;DR: Van Dyke as mentioned in this paper measured the potentials at which viscous jets or drops first appear in a parallel electric field and compared with calculations of A. B. Basset and found that their stability is due to mechanical rather than electrical causes, like a stretched string, which is straight when pulled but bent when pushed.
Abstract: Fine jets of slightly conducting viscous fluids and thicker jets or drops of less viscous ones can be drawn from conducting tubes by electric forces. As the potential of the tube relative to a neighbouring plate rises, viscous fluids become nearly conical and fine jets come from the vertices. The potentials at which these jets or drops first appear was measured and compared with calculations. The stability of viscous jets depends on the geometry of the electrodes. Jets as small as 20 μm in diameter and 5 cm long were produced which were quite steady up to a millimetre from their ends. Attempts to describe them mathematically failed. Their stability seems to be due to mechanical rather than electrical causes, like that of a stretched string, which is straight when pulled but bent when pushed. Experiments on the stability of water jets in a parallel electric field reveal two critical fields, one at which jets that are breaking into drops become steady and another at which these steady jets become unsteady again, without breaking into drops. Experiments are described in which a cylindrical soap film becomes unstable under a radial electric field. The results are compared with calculations by A. B. Basset and after a mistake in his analysis is corrected, agreement is found over the range where experiments are possible. Basset’s calculations for axisymmetrical disturbances are extended to those in which the jet moves laterally. Though this is the form in which the instability appears, calculations about uniform jets do not seem to be relevant. In an appendix M. D. Van Dyke calculates the attraction between a long cylinder and a perpendicular plate at a different potential.
1,364 citations
"Experimental investigation of the g..." refers methods in this paper
...Taylor [6–9] produced useful experimental evidence on the conical shape of the protrusion from which a jet sometimes leaves the surface of a pendant liquid drop....
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