method of creating a variety of ultrathin fibers
Electrospinning is a fiber production method that employs electric force to draw charged jets of polymer solutions or polymer melts. The diameters of these jets are generally in the order of some hundred nanometers. When an external electrostatic field is applied to a conductive fluid, for example a spinning solution, a suspended conical droplet, which is called Taylor cone, is formed.
Electrospinning occurs when the electrostatic field is strong enough to overcome the surface tension of the liquid. The liquid droplet then becomes unstable and a tiny jet is ejected from the surface of the droplet. The ejected jet is deposited on a collector as a result of the electrostatic field that is provided by a power supply between the spinneret and the collector and is applied to spinning droplets. As the tiny jet reaches the collector, an interconnected web of fine sub-micron size fibers is collected on the collector.
Electrospinning provides a relatively versatile method of creating a variety of ultrathin fibers (nanofibers). Nanofibers with some specific properties can be prepared if appropriate solution or processing parameters are performed. However, electrospinning generally has relatively low productivity compared to other spinning processes, because the polymer solution has to be fed at comparatively slow rates and only electrostatic forces are used to obtain the ultrathin fibers.
In order to overcome the aforementioned drawback, we employed blown electrospinning technique for increasing throughput up to 3 times compared to conventional electrospinning systems. The combination of the air blowing force and the electrostatic force is capable of overcoming the high surface tension of the polymer solution, therefore, the rate of converting solutions to nanofibers increase significantly. Additionally, the solvent evaporation is accelerated by blowing air which is a necessary condition for the fiber formation before the jet reaches the collector during the process. Therefore, many useful polymers, which previously could not be electrospun, now are processed easily by using the blown electrospinning process.