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In this study, we examined the effect of applied electrostatic voltages and the types of electrical charging on jet movement, fiber productivity, fiber diame- ter and deposited configuration by two inverse polarity systems, termed as spinneret and collector charging sys- tems. Jet movement parameters such as Taylor cone, straight jet length, whipping angle, and pitch of whipping loop are examined and compared. The results show that the electronegative collector charging system or the elec- tropositive spinneret charging system is superior to their contrastive system in terms of smaller fiber diameter, com- pact fiber deposited configuration, and higher fiber pro- ductivity. Optimal applied voltage found was 25 kV for electronegative collector charging system and 30 kV for electropositive spinneret charging system and resulted in finest fiber diameter (209 nm for electronegative collector charging system and 247 nm for electropositive spinneret charging system). Polyvinyl acetate solution jet is easier to be ejected, stretched, and accelerated under electropositive charging. The spinning jet with electropositive charges can be achieved either in the spinneret charging system by using electropositive charger or in the collector charging system by using electronegative charger. This finding is an important guideline for the designing of electrospinning device. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 126: E89- E97, 2012

Bubble-electrospinning is suggested to produce micro/nano fibers. Contrary to classical electrospinning where a high voltage is applied to overcome the surface tension of the Taylor's cone, in bubble-electrospinning, the voltage is applied to overcome the bubble's surface tension, which mainly depends upon the size of the bubble. Instead of single jet, millions of charged jets are observed simultaneously. In this article, we design a single bubble-electrospinning to primarily study the effect of concentration on the spinning procedure. Polyvinylpyrrolidone (PVP) is used in the experiment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Poly(vinyl alcohol) (PVOH) was electrospun using different methods to charge the polymer solution. A positive high voltage relative to the collecting electrode significantly increased the fibre deposition rate. Electron microscopy showed that approximately half of the increase in fibre mass was due to thicker fibres being deposited. The current flowing from the grounded electrode was measured to determine the charge carried on the PVOH jet. This showed that for a positive voltage charging condition there is a much larger current and hence more charge carriers generated in the PVOH solution. As a result, more mass is ejected from the Taylor cone, implying that a positive voltage also produces longer fibre for a given time period. We also tested whether different substrate materials caused any variation when the charging conditions were changed. Statistically significant variation between substrates was only found when the substrate was an insulator and was expected to support a high deposition rate. This confirms the view that the PVOH fibre arrives at the collecting electrode carrying a charge that must be neutralized, otherwise a repulsive charge will form where the fibre is deposited and some fibre will be lost to any alternative earth. In electrospraying, charge carriers are generated using associated redox reactions. Thus, for electrospinning a lack of symmetry in these reactions may result in the generation of different quantities of charge carriers in the PVOH solution and changes in the mass deposition rate of electrospun fibre.

Electrospinning is a flexible and efficient method for producing nanofibers by using relatively dilute polymer solution. However, there are many parameters related to material and processing that influence the morphology and property of the nanofibers. This study investigates the influence of electric field and flow rate on diameter and tensile properties of nanofibers produced using polyacrylonitrile (PAN)-dimethylformamide (DMF) solution. Stability of the spinning jet is investigated via fiber current measurement and an image system at different electric fields and solution flow rates. It is observed that a set of electric field and flow rate conditions favor producing thinnest, strongest, and toughest nanofibers during electrospinning process. Other conditions may lead to instability of the Taylor cone, discontinuous jet, larger diameter fiber, and lower mechanical properties. Finally, a simple dynamic whipping model is adopted to correlate the nanofiber diameter with volumetric charge density and is found to be excellent validating our experimental results. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41918.

A new melt electrospinning system equipped with a line-like laser beam melting device developed for the mass production of nanofibers is introduced; this system enables fibers to be produced from locally melted polymer sheets in the presence of an electric field. Using this system, fibers were produced from poly(ethylene-co-vinyl alcohol)(EVOH) and Nylon 6/12 sheets. The fiber formation mechanism was investigated with a video camera and a thermographic camera. It was found that (1) many Taylor cones are formed on the molten end surface of the sheet at almost regular intervals; (2) a single fiber is produced from the apex of each Taylor cone; and (3) the temperature in the Taylor cone changes markedly during the fiber production. Furthermore, it is found that fibers with an average diameter smaller than 1 μm can be produced from EVOH and Nylon 6/12 sheets by the optimization of manufacturing parameters such as laser output power, voltage, sheet thickness and the feed rate of the sheet. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010