Jonathan Stanger

Manipulation of electrospun fibres in flight: the principle of superposition of electric fields as a control method

This study investigates the magnitude of movement of the area of deposition of electrospun fibres in response to an applied auxiliary electric field. The auxiliary field is generated by two pairs of rod electrodes positioned adjacent and parallel to the line of flight of the spun fibre. The changes in shape of the deposition area and the degree of movement of the deposition area are quantified by optical scanning and image analysis. A linear response was observed between the magnitude of movement of the deposition area and voltage difference between the auxiliary and deposition electrodes. A squeezing effect which changed the aspect ratio of the deposition area was also observed to result from the application of symmetric electrical fields. Statistical analysis showed that the deflection and squeezing responses can be thought of as independent control actions. The results from this experiment suggest this particular application of superposition of electric fields could be used as to control the flight path of an electrospun fibre.

Functional nanofibers in clothing for protection against chemical and biological hazards

Functional nanofibers have great potential to improve protection against chemical and biological warfare agents. This chapter reviews the history of chemical and biological warfare and existing protective technologies. The use of electrospinning to produce nanofibers for protective applications is also introduced. Previous studies demonstrate the applicability of electrospun nanofibers in protective fabric technologies. Advantages of these next-generation protective materials include high penetration resistance, excellent breathability, low basis weight, low pressure drop, the potential for the incorporation of surface chemical functionality and simple processing equipment. Finally, the main development issues and potential research directions of electrospun nanofibers in protective applications are discussed.

Effect of salts on the electrospinning of poly(vinyl alcohol)

Fibres with a diameter in the nanometer range were electrospun from aqueous poly(vinyl alcohol) (PVOH). In order to improve the mass deposition rate and decrease the final fibre diameter salts (NaCl, LiCl, LiBr and LiF) were added to the solution. The aim was to increase the charge density and hence increase the electrostatic forces on the fluid. It was found that with increasing salt concentration the charge density did increase. However the mass deposition rate was found to decrease and the final fibre diameter was found to increase. The decrease in mass deposition rate is explained by considering the concept of a virtual orifice. The increase in the final fibre diameter is explained by considering the charge distribution in the jet when it behaves like a conductor compared to when it behaves like an insulator. Both mechanisms result from the increase in conductivity of the PVOH solution without significantly modifying other solution properties when salt is added.