Electrospinning material properties

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. 

Blend electrospinning occurs when two or more miscible solutions are combined into a single feed system and fed through a common spinneret for desired final material properties (Fig. 10.5). Although this procedure is not the most common technique, the advantage of this particular method is its ability to modify the chemical... 

The first step to determine the properties of the final end product is the selection of solution parameters, which consist of the polymer and solvent material properties, as well as those of the solution mixture. The high solubility of the polymer of interest in a particular solvent is a prerequisite for uniform electrospinning. The major scaffold characteristics such as chemical composition, mechanical integrity, degradation rate and by-products will be determined by polymeric materials. On the other hand, the solvent properties will primarily determine morphological characteristics of electro-spun scaffolds such as fiber size, porosity and fiber morphology. 

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. 

In addition, electrospinning of polymer melt is also interesting as no solvent is involved in the process. Further research is warranted to examine the effects of both operating conditions and material properties on the properties and morphologies of nanofibres electrospun from polymer melts. 

Figure 1 Electrospinning setup and properties of electrospun materials, (a) A schematic illustration of the basic electrospinning configuration, with typical operating parameters and length scales labeled, (b) A microscopic view of a typical electrospun fiber mat. Some typical material properties are listed in the figure.

The last method to be discussed, which is used to form polymer/ceramic composites by electrospinning, is extremely different to the methods previously described, but worth mentioning. Zuo et al. [129] used a method to create a composite scaffold that is actually the reverse of what most people are doing. Instead of mineralizing the nanofibers, Zuo et al. actually incorporated electrospun polymer nanofibers into a ceramic bone cement in order to form a composite scaffold. It was found that by incorporating electrospun nanofibers into the cement, the scaffold became less brittle and actually behaved similarly to that of a ductile material because of the fibers. Composite scaffolds with different polymers and fiber diameters were then tested in order to determine which scaffold demonstrated the most ideal mechanical properties. However, no cell studies were conducted and this method would most likely be used for a bone substitute instead of for bone regeneration applications. 

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