Simon Feasey and Iain Hosie, Revolution Fibres, explain the process of electrospinning nanofibres.
Taylor cone: the characteristic droplet shape formed by fluid on the tip of the needle when under the effect of an electric field as in the process of electrospinning.
Electrostatic field: when two objects in each other’s vicinity have different electrical charges, an electrostatic field exists between them.
Collector/collector plate: the surface onto which the electrospun nanofibre is deposited. In this video clip, two collectors are illustrated. The first is a metal disc holding a filter. The disc spins around during the electrospinning process and the nanofibre is deposited over the surface of the filter. In the second example, nanofibres are deposited onto a removable sheet, a roll of material that runs through the Komodo.
What happens is you prepare a polymer in a solution use a solvent to break down a typical polymer like nylon or polyester into solution. You then charge that solution with a very, very high voltage, anything up 50, 60 000 volts. And you have a collector plate which is the opposite charge or neutral, so you actually create an electrostatic field.
So within that electrostatic field, you’ve got a huge build-up of electrons trying to get to the other side, so the solution actually beads up into a droplet, it forms what’s called a Taylor cone. The Taylor cone is like the feeder, and the fibre spins in the electrostatic field, and as it spins, it speeds up and goes faster and faster and stretches. So the action of the stretching of the fibre is reducing the diameter continuously. So when you get all the parameters right, you can end up depositing a dry fibre of a nanoscale onto the surface of a collector plate.
Nanofibres form on a collector because they’re very, very difficult to handle. We need to collect them on some sort of fabric or removable sheet, depending on that end application, if we want to keep the fabric in place like in a filter or if we want to remove the collector later on. This is how we deal with it in composites, for example. So the fibres need to land onto something, and we have a roll of material which will enter the machine, we apply the nanofibre and then the roll is rewound at the other end.
Simon Feasey, Iain Hosie
The Royal Society of New Zealand NZ, TVNZ 7 in partnership with the Ministry of Business, Innovation and, Business & Employment