Electrospinning process parameters

Electrospinning Processing Parameters Control of the Nanofiber Morphology... 

Basically, electrospinning process parameters can be classified into three differenttypes solution, process, and ambientparameters. Viscosity, conductivity, and surface tension which affect instantly dimensions and morphology of fiber. Viscosity is one of the most important solution parameters. 

In electrospinning, process parameters are typically considered as the applied electric field, working distance, flow rate, and, in some cases, collector [rotor] velocity. 

Chen, M., Ratra, R.K., Warner, S.B. and Bhowmick, S. 2006b. Optimization of electrospinning process parameters for tissue engineering scaffolds. 

Sukigara, S., Gandhi, M., Ayutsede, J., Micklus, M., and Ko, F. "Regeneration of Bombyx mori silk by electrospinning - part 1 Processing parameters and geometric properties". Polymer 44(19), 5721-5727 (2003). 

RSM procedure to optimize the process parameters for the electrospinning silk is shown in Figure 27. 

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. 

In addition to the process parameters, a number of system parameters play an important role in fiber formation and the obtained structure. System parameters include molecular weight, molecular weight distribution, polymer architecture, and solution properties. Solution properties play a particularly important role. In relation to their impact on the electrospinning process, these factors can be ranked as follows polymer concentration, solvent volatility, and solution conductivity. 

Nanoscaled PCL and PCL/gelatin fibrous scaffolds with immobilized epidermal growth factor (EGF) were prepared for the purpose of wound-healing treatments [80]. The tissue scaffolds were fabricated by electrospinning and the parameters that affect the electrospinning process were optimized. In this study, the fiber diameters were 488 114 nm and 663 107 nm for PCL and PCL/gelatin scaffolds, respectively, and the porosities were calculated as 79% for PCL and 68% for... 

Electrospinning process produces very fine fibers and this is one of the very few methods from which fibers of sub-micron size can be produced. So it becomes immensely important to understand the behavior of fiber diameter and fiber diameter distribution in the electrospun web as impacted by the independent variables (processing parameters). Understanding how fiber diameter and diameter distribution are affected by the processing parameters is essential to produce webs with desired fiber diameter and distribution. 

The following parameters and processing variables affect the electrospinning process (i) system parameters such as molecular weight, molecular weight distribution and architecture (branched, linear, etc.) of the polymer, and polymer solution properties (viscosity, conductivity, dielectric constant, and surface tension, charge carried by the spinning jet) and (ii) process parameters such as electric potential, flow rate and concentration, distance between the capillary and collection screen, ambient parameters... 

This chapter is devoted to a discussion of the fabrication of nanofibres as a biomaterial and the use of them as such. Several approaches to this fabrication have been included, focusing on the extraction of nanofibrils from natural materials by both mechanical and chemical means and electrospinning from a wide range of materials (both natural and synthetic). Of these, electrospinning has received greater attention for a number of reasons it is convenient to operate, its processing parameters can be well controlled and it is the most likely to reach the scale of mass, industrial production. 

Okutan, N., Terzi, P., Altay, F., 2014. Affecting parameters on electrospinning process and characterization of elecfrospun gelatin nanofihers. Food Hydrocolloids 39 (August), 19—26. Available from http //dx.doi.Org/10.1016/j.foodhyd.2013.12.022. 

In the electrospinning process, the following three parameter classes have relative effects on the resulting fiber properties ... 

The effects of processing parameters on the morphology of electrospun nanofibres are summarised in a processing map (Figure 4.14). A suitable combination of the processing parameters should be attained to electrospin polymers into nanofibres... 

Fillers and additives may also interact with the solvent, with the polymer, or with both. The electrospinnability of tbe solution may change as a result of these interactions, but it may also remain imcbanged, regardless of tbe additive. It has, for example, been shown that conductive solutions can form different kinds of three-dimensional loose structures on the substrate, instead of a tbin coating layer attached to the substrate surface. Tbe form of these structures can vary from fibrils perpendicular to the substrate surface to a layer with a fluffy cotton-like structure. Fibrils can even extend to cover tbe entire electrospinning zone. If this kind of conductive fibrous structure connects tbe nozzle and collector plate, the electric field discharges and the process stops. The optimisation of the process parameters for ternary systems can be even more challenging than for binary systems composed only of polymer and solvent. 

The parameters involved in the electrospinning processes that affect the nanofiber geometry and structure can be divided into two groups (i) System parameters such as polymer molecular weight, molecular weight distribution, polymer architecture (branched, linear), concentration of the polymer solution and its properties, including viscosity, electrical conductivity, and surface tension and (ii) Process parameters such as applied electric voltage, polymer flow rate, distance between the needle tip and the collector, ambient parameters such as temperature, humidity, and air velocity in the chamber, and motion of the collector (Frenot and Chronakis 2003). 

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