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Nanotechnology with unique properties is taken one of the most promising technologies interested by many scientists in everywhere in recent years (Lu & Ding, 2008; Reneker, Yarin, Zussman, & Xu, 2007; Vonch, Yarin, & Megaridis, 2007).
Research and development in nanotechnology are directed toward realizing and creating improved materials, devices, and systems that exploit these new properties (Sawhney, et al., 2008).
Hence, researchers started with analysis these properties (Fang, Niu, Lin, & Wang, 2008; Vonch, et al., 2007).
When the diameters of polymer fiber materials reduce from micrometers to nanometers, several characteristics like large surface area to volume ratio and High porosity are changed compared to other known form of the material in many research studies (Rafiei, Maghsoodloo, Noroozi, Mottaghitalab, & Haghi, 2013).
Electrospinning, as a branch of nanotechnology, has attracted a great deal of interest as a novel technique (Brown & Stevens, 2007).
Electrospinning, which is likewise known as electrostatic spinning, is perhaps the most versatile process (Wang, Fu, & Li, 2009).
It is a fascinating, very uncomplicated, inexpensive and powerful process used to prepare polymeric fibers with diameters ranging in nanometers (Lukáš, et al., 2009; C. Wang, Cheng, Hsu, Chien, & Tsou, 2011).
Nanofibers, especially polymer nanofibers, are promising in a vast range of potential applications, such as wound healing and drug delivery (Wang, et al., 2009).
Nanofibers are formed from a polymer solution or melt with a high potential power source. Then this liquid is passed from a capillary and collected on the collector (Beachley & Wen, 2010; W. J. Li, Laurencin, Caterson, Tuan, & Ko, 2002).
Hither, a common electrospinning set-up shows in particular in Figure 1.
Figure 1. Sections of electrospinning process: (1) Polymer solution. (2) Syringe. (3) High voltage. (4) Taylor cone. (5) Whipping instability. (6) Nanofibers formation. (7) Collector
The electrospinning process is grounded upon the simple concept that creates nanofibers through an electrically charged jet of polymer solution or polymer melt. When the voltage is initially applied to the solution fluid, the droplet at the nozzle distorts into the form of a cone. The final conical shape has come to be known as the Taylor cone. These changes are due to the rivalry between the increasing solution charge and its surface tension. When the applied voltage is sufficient the electrostatic force in the polymer and solvent molecules can overcome the surface tension enough charge to overcome surface tension, a stream is turned out from the tip of the Taylor cone. The solution is drawn as a jet towards an oppositely charged collecting plate, which will cause the charged solution to speed up towards the collector. The solvent gradually evaporates, and a charged, solid polymer fiber is allowed to accumulate on the collection plate (Huang, Zhang, Kotaki, & Ramakrishna, 2003; Pham, Sharma, & Mikos, 2006).
Various factors have been widely investigated and discussed as to how to obtain better control of electrospinning process and electrospun fiber diameter. These factors that are contemplated to have a primary effect on the formation of uniform fibers are the process parameters, environmental parameters, and solution parameters (Angammana, 2011; Bhardwaj & Kundu, 2010; Lu & Ding, 2008; Rafiei, et al., 2014; Tan, Inai, Kotaki, & Ramakrishna, 2005; Wang, et al., 2011).