Gary Peeters

Fabrication and Characterisation of Nanofibres by Meltblowing and Melt Electrospinning

Fabrication of nanofibres has become a growing area of research because of their unique properties (i.e. smaller fibre diameter and higher surface area) and potential applications in various fields such as filtration, composites and biomedical applications. Although several processes exist for fabrication of nanofibres, electrospinning is considered to be the simplest. Most of the research in electrospinning is based on solution rather than melt. The feasibility of fabricating nanofibres of polypropylene (PP) by meltblowing and melt electrospinning has been investigated in this paper. In meltblowing different fluids such as air and water were fed at different inlets along the extrusion barrel for the fabrication of nanofibres whereas in melt electrospinning it was achieved by using different additives. The results obtained by using water in meltblowing were better with respect to the morphology and fibre uniformity compared to air. In melt electrospinning although all the additives (i.e. sodium oleate (SO), polyethylene glycol (PEG) and polydimethyl siloxane (PDMS)) helped in reducing the fibre diameter, only SO was effective to reduce the diameter down to nanoscale. It was concluded that both the solvent-free processes have the potential to substantially increase the production of nanofibres compared to solution electrospinning.

Thermochromic composite fibres containing liquid crystals formed via melt extrusion

A three-layered composite fibre has been generated via a modified wire-coating melt co-extrusion process. The continuous fibre consists of a thermochromic liquid crystalline (TLC) layer encapsulated between a transparent polypropylene outer sheath and a black polyether ether ketone inner core. The fibres exhibit clear thermochromic behaviour consistent with the behaviour of unincorporated TLCs, and have been formed into a textile. The presence of the black inner core was found to be the key for the clear retention of colour within the fibres against both white and black backgrounds. The temperature-sensitive fibres and textiles can be applied to a variety of thermal mapping applications, such as in the medical and engineering fields, due to the tunable nature of TLCs.

Mechanism of Nanofibre Fabrication by Meltblowing

Fabrication of nanofibres has become a growing area of research because of their unique properties (i.e. smaller fibre diameter and higher surface area) and potential applications in various fields such as filtration, composites and biomedical applications. The mechanism of nanofibre fabrication by meltblowing process with the injection of different fluids (such as air and water) has been investigated in this paper. In the meltblowing equipment the fluids were injected at a vent port along the extrusion barrel, for the fabrication of nanofibres. The injection of water resulted in better fibre morphology compared to the injection of air. Nanofibres were fabricated by the drafting action of the high-velocity flow of the heated air and the steam in the extruder. The fibres collected were straight prior to the fluid injection and coiled fibres were collected with the injection of fluids. Three types of fibres such as ribbon shaped, fused and branched fibres were obtained in addition to the circular fibres.

A Spherical Lens for the SKA

Spherical refracting lenses based upon the Luneburg lens offer unique capabilities for radioastronomy, but the large diameter of lens required for the Square Kilometre Array (SKA) means that traditional lens materials are either too dense or too lossy. We are investigating a composite dielectric that theoretically offers extremely low loss and low density, and is suitable for low-cost mass production. We describe our progress towards realising this material and demonstrating the manufacturing concept, via the manufacture and testing of a small (0.9 m) spherical lens.