Electrospinning of composite silica/PVA nanofibres and testing of their effects on the impedance of an air gap.

Abstract

Electrospinning is a quick method of producing long continuous fibres with diameters in the nanometre range. At first, only polymers were electrospun. In recent practices, inorganic materials have also been electrospun by combining them with polymers in the electrospinning solution. A number of experiments dealing with electrospinning and applications of silica nanofibres have been presented by different authors. None of these experiments dealt with any electrical properties of silica nanofibres. The experimentation presented herein deals with the effects of composite silica/PVA nanofibres on the electrical impedance of an air gap. Literature covering electrospinning in general and electrospinning of silica is discussed in detail. For the electrospinning process, parameters affecting the morphology of nanofibres are presented by referring to experiments done by other researchers. For silica, the theory behind formation of a silica sol is discussed. All apparatus used in the experimentation is listed. In particular, the electrospinning setup had to be designed, built and optimized. The design of the setup is presented. Included in the design is the construction of a high voltage DC supply to be used to apply high voltage to the spinneret of the setup. The optimization of the setup and the solution used to electrospin fibres is covered in the discussion of the experimental procedure. The fibres were successfully fabricated with reasonable uniformity and nano-sized diameters. These parameters were checked using a scanning electron microscope. Some images taken of the fibres by the microscope are presented with the calculated average fibre diameters. The rest are in the appendix. The chemical composition of the fibres was confirmed using Fourier transform infra-red, the results of which are discussed. The impedance of an air gap with and without fibres was calculated using values measured by an oscilloscope. Measurements were taken over a range of frequencies to observe the change in the reactive component of the impedance. Based on results obtained, it was concluded that composite silica/PVA nanofibres reduce the impedance of an air gap and are therefore ineffective as an insulating material.