Study Unit 2.5 Nanofibres Flashcards
Define Nanofibre
Although the National Science Foundation (NSF) defines nanofibres as having at least one dimension of 100 nanometre (nm) or less, in some textile sectors nanofibres are often considered as fibres as having a diameter of less than 0.5 micrometres (500 nanometres).
The nanometre represents a billionth of a metre.
Nanofibres can be produced from:
Nanofibres can be produced from bi-component fibres such as Islands-In-The-Sea fibres.
An electrospinning process can produce nanofibres with diameters of less than 100 nm.
An electrospinning process can produce:
An electrospinning process can produce nanofibres with diameters of less than 100 nm.
Various manufactured polymers, including polyester and acrylic, and natural polymers such as chitosan can be used to produce the nanofibres.
Explain the electrospinning process
In the process, a polymer is dissolved in a solvent and a high voltage electric field is applied to the solution. This causes a thin jet of solution in the form of a very fine filament to be produced from the tip of a fine orifice or spinneret. This filament is collected onto a rotating or stationary collector where it accumulates to form a web of nanofibres. This process can produce nanofibres with diameters as low as 50 nanometres although the collected web usually contains fibres with varying diameters from 50 nm to several 100 nm.
Electrospinning then and now
This method has been known since 1934 when the first patent on electrospinning was filed. At present, the production rate of this process is very low and research efforts are aimed at increasing productivity and producing fibres which are consistently less than 100 nm.
Nanofibres can be produced from bi-component fibres such as Islands-In-The-Sea fibres
From 240 to possibly as much as 1120 filaments (the islands) are surrounded by a dissolvable polymer (the sea). Dissolving the polymer leaves the matrix of nanofibres, which can be further separated by stretching or mechanical agitation.
The resulting fibres can have a diameter of approximately 300 nm.
Nylon and polyester are the two polymers that this method use to produce nanofibres.
What unusual properties makes nanofibres exciting?
Nanofibres are an exciting new class of material which have unusual properties because of their high surface to weight ratio.
Uses of nanofibres
They can be used for several value added applications such as medical products, filters, wipes, composites, garments, insulation and energy storage.
