Electrospinning process

Wang, H., Shao, H.L., and Hu, X.C. "Structure of silk fibroin fibers made by an electrospinning process from a silk fibroin aqueous solution". J. Appl. Polym. Sci. 101(2), 961-968 (2006). 

The morphologieal struetme ean be slightly changed by changing the solution flow rate as shown in Figure 12. At the flow rate of 0.3 ml/h, a few of big beads were observed on the fibers. The flow rate eould affect electrospinning process. When the flow rate exceeded a critical value, the delivery rate of the solution jet to the capillary tip exceeded the rate at which the solution was removed from the tip by the electric forces. This shift in the mass-balanee resulted in sustained but rmstable jet and fibers with big beads were formed [56]. 

Sukigara et al.[78] used RSM analysis (Response Surfaee Methodology) to the experimental results to develop a processing window which will produce nanoscale regenerated silk fibers by electrospinning process. RSM is used in situations where several variables influence a feature (called the response) of the system. The steps in the procedure are described briefly as follows. 

Electrospinning is a simple and versatile method for generating ultra-thin fibers for a large variety of materials including polymers, composites, and ceramics (Li and Xia, 2004). Hou et al. (2009) reported the preparation of doped LaP04 nanofibers and microbelts through a combined sol-gel and electrospinning process. The obtained nanofibers and microbelts are made up of small NPs. 

Doshi J, Reneker DH (1995) Electrospinning process and applications of electrospun fibers. J Electrostal 35(2-3) 151-160... 

Wang C et al (2010) Biodegradable core/shell fibers by coaxial electrospinning processing, fiber characterization, and its application in sustained drug release. Macromolecules 43(15) 6389-6397... 

Kim GH (2006) Electrospinning process using field-controllable electrodes. J Polym Sci B Polym Phys 44(10) 1426-1433... 

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. 

Fig. 4 Synthesis of chitosan-PEG-FA (a), and electrospinning process for generating adenoviral (Ad)/chitosan-PEG-FA nanocomplexes (b)...

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... 

Recently, PCL containing bovine bone hydroxyapatite (HA) and hydroxyapa-tite/Ag (HA-Ag) composite nanoflbers were prepared via an electrospinning process [43]. The morphology, structure and thermal properties of the PCL, PCL/HA, and PCL/HA-Ag composite nanoflbers before and after immersion in SBF were characterized. SEM images revealed that the nanoflbers were well-oriented and incorporated the HA-Ag nanoparticles well. Mechanical study revealed that the yield stress of PCL/HA-Ag composite nanoflbers showed a higher value than that of PCL/HA composite, possibly due to the addition of metallic Ag nanoparticles [43]. 

The electrospinning process was capable of incorporating the nanoparticles on the surface of the nanowebs. This is clearly evident from the regular pattern of the nodes in the transmission emission micrograph (Figure 8.8) and from the individual MgO nanoparticle embedded on the surface of a PEO nanoflber (Figure 8.9). 

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