Rotary Jet Spinning of Polymer Fibres

Polymeric nanofibres can be produced from a variety of methods such as electrospinning and melt blowing, with fibres being produced having applications in many sectors such as biomedicine, composites and filtration. Existing methods are not however capable of producing nanofibres to commercial volumes in an energy efficient way. In this research we investigate a new method of producing nanofibres, namely Rotary Jet Spinning (RJS), which is a relatively new method of fibre production similar to candyfloss production, where centrifugal forces are used to expel jets of polymer from a state of melt or solution in order to produce polymeric fibres. We investigate this method in detail, initially concentrating on the comparison between electrospinning and RJS. Firstly, it was found that electrospinning produced slightly smaller fibre diameters compared to RJS over a broader range of solution concentrations. Secondly, the ability to produce high modulus fibres was investigated by means of an imidization technique, where polyamic acid solution was produced and spun into fibres before conversion to a co-polyimide fibre with an elastic modulus of around 40 GPa. In the third experimental chapter, the viscosity reliability of the RJS process was evaluated by means of computational fluid dynamics simulations, where it was shown that low viscosity (1-10 Pa.s) Newtonian fluids are required to establish fibre production. For fluids with lower viscosities, beading occurred in solution spinning and droplets were produced from melt spinning. Viscosities higher than the recommended value resulted in blockage, with no fibres being produced from either method. Lastly, the production of ceramic fibres was evaluated to establish the ability of the RJS process to produce a ceramic nanofibre. Fibres on the nanoscale were not achieved, however a variation in solvent volatility and crosslinking time were factors in fibre diameter reduction, with solvent variations highlighting the potential of this process to achieve the required fibre size from RJS and thereby demonstrating this technology as a viable option for high volume fibre production.EPSRC grant number 150219