Collector, electrospinning

Fiber jet speed and material elasticity are two of the most important parameters involved in the jet-mandrel interaction and each of these properties are influenced by multiple electrospinning parameters, such as solution conductivity, viscosity, voltage, and feed rate. In addition, material properties cannot be accurately predicted without knowing the exact degree of solvent evaporation at the point when fibers are taken up by the collector. 

Under normal electrospinning conditions, the deposition area of an electrospinning jet can be undesirably large and difficult to predict. This can lead to difficulties in precise and repeatable fabrication of uniform nanofiber arrays, and materials may be wasted. It is desirable to explore methods to control the deposition of an electrospinning jet in terms of both focused fiber deposition area and controlled placement of the fiber deposition area. The range of fiber deposition is usually decreased as the needle-to-collector distance is decreased however, this alone may... 

Katta P et al (2004) Continuous electrospinning of aligned polymer nanoflbers onto a wire drum collector. Nano Lett 4(11) 2215—2218... 

Raflque J et al (2007) Electrospinning highly aligned long polymer nanoflbers on large scale by using a tip collector. Appl Phys Lett 91 063126... 

Despite the fact that the electrospinning technique is relatively easy to use, there are a number of process parameters that can greatly affect fiber formation and structure. Listed in order of relative impact to the electrospinning process, the most important parameters are applied voltage, polymer flow rate, and capillary-collector distance. All three parameters can influence the formation of nanofibers with bead-like defects. 

Figure 2 SEM micrograph of titania fibres producing by electrospinning at 18KV and distance of collector of 8cm at flow rate of 0.5mlh .

Nanofibre mats are produced by the electrospinning process as a result of the potential gradient between needle tip and collector. Various polymers have been successfully electrospun into ultrafine fibres mostly from solvent solution and some in melt form... 

Figure 4.2 Schematic illustration of the conventional set-up for electrospinning. The insets show a drawing of the electrified Taylor cone, bending instability, and a typical SEM Image of the nonwoven mat of PET nanofibers deposited on the collector. The bending Instability Is a transversal vibration of the electrospinning jet. It is enhanced by electrostatic repulsion and suppressed by surface tension...

Electrospinning uses a high-voltage electrical field (typically 10-20 kV) to form micro- and even nanoscale fibres from a suspended droplet of polymer melt or solution [118]. When the repulsive electrostatic interactions overcome the droplet s surface tension, a Taylor cone is formed and a polymer jet is ejected from the tip of this Taylor cone [119]. The polymer jet is then accelerated towards a grounded collector screen. As the jet moves through the air, a stretching process occurs and the solvent evaporates which results in a non-woven polymer fabric or polymer mat [120]. Electrospinning has already been applied for both synthetic as well... 

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