Electrospinning affecting factors

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... 

Solvent volatility is an important factor in electrospinning. Since electrospinning requires a quick evaporation rate and phase separation, vapor pressure of the solvent affects the dr5dng time and evaporation rate. Other parameters affecting evaporation rate are boiling point, specific heat, enthalpy and heat of vaporization, rate of heat supply, interaction between solvent molecules, surface tension of the liquid, and air movement above the liquid surface. 

Besides the above-noted parameters, there exist some other factors affecting electrospinning, such as the surrounding environment (e.g., humidity [20]). However, all these parameters interact and cannot be individually considered to achieve a perfect fibrous scaffold. All parameters must be comprehensively studied and optimized for electrospinning control. 

The relative importance of electrospinning parameters on the value of CA calculated by Equation (4) and is shown in Figure 6. It can be seen that, all of the input variables have considerable effects on the CA of electrospun liber mat Nevertheless, the solution concentration with relative importance of 49.69% is found to be most important factor affecting the C A of electrospun nanofibers. These results are in close agreement with those obtained with RSM. 

In summary, the thermal properties of the electrospun form-stable PCM/polymer composite fibers can be affected dramatically according to different types of PCMs [14, 31, 38, 43, 48] and various PCM/polymer mass ratios or PCM contents [14, 33, 37-39, 41, 43, 48, 49]. The former factor is in charge of the intrinsic thermal properties of the novel thermal-storage materials, because it fixes the phase transition temperatures and limits the maximum value of the latent heats of the composite fibers. The latter one plays a key role in the latent heats of the form-stable PCM/polymer composite fibers but has less effect on their phase transition temperatures. All those novel composite fibers showed good thermal stability and reliability no matter what electrospinning methods were applied. 

In theory, any factor that affects the electrospinning process also provides a means to control the fibre morphology. In practice, however, only factors with a noticeable and reliable influence on fibre morphology can be employed for this purpose. Methods of controlling the fibre morphology have been reported based on either the operating parameters or the material properties. 

The porosity of a nanofiber-based scaffold is a key factor in controlling the degradation profile. A number of methods have been developed for manipulating the porosity of a nanofiber scaffold, including those based on variation of the size of nano fibers, salt leaching, cryogenic electrospinning, and removal of a sacrificial component. These methods will be discussed in Section 9.2.6, as cell infiltration is also affected by the porosity. 

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