Electrospinning solution parameters

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. 

Processing parameters include the distance between the collector and the tip, the geometry of the collector, the electrical potential,and the flow rate. Solution parameters include the viscosity, conductivity, and surface tension of the polymer solution or melt, and the environmental parameters include the temperature and humidity" in the electrospinning chamber. The concentration of polymer solution determines if a continuous... 

Polymer solution parameters are certain variables related to the physical properties of the polymer solution used for electrospinning nanofibers such as polymer concentration, polymer solution viscosity, polymer molecular weight, solution charge density, conductivity, volatility, surface tension, dielectric constant, and dipole moment. These variables are hard to be altered since changing one of those variables would consequently change some of the others. An example of that is the alteration in the polymer solution viscosity upon changing its conductivity (Pham et al. 2006). 

Electrospinning ultrafine fibers and process parameters. A small amount of pyridine added to the electrospinning solution avoided formation of beaded nanofibers at low concentrations. 

The parameters impacting the electrospinning process can be categorized into solution parameters (surface tension, concentration, viscosity and conductivity), processing conditions (voltage, distance from needle to collector, type of collector, flow rate) and ambient conditions (humidity, pressure and temperature) [90, 91]. Based on the interaction of all these factors, the morphology and size of resultant nanofibers can be changed. 

With the same idea of the previous works and taking into accoimt the advantages of electrospinning technique, a possible solution to problems concerning antibiotics elution from PMMA cement coatings could be the development of electrospun mats with a controllable porosity. The mat and fibers morphologies obtained from this technique can be tailored in order to fulfill the needed characteristics by choosing different processes and solution parameters [161]. 

Nakano, A., Mild, N., Hishida, K., Hotta, A. Solution parameters for the fabrication of thinner silicone fibers by electrospinning. Phys. Rev. E Stat., Nonlin, Soft Matter Phys. 86, 011801 (2012)... 

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. 

This section deals with the optimization of electrospinning process and solution parameters using statistical modeling to obtain uniform fibers. Two polymers namely, PEO and chitosan, have been used to investigate the interaction effects on electrospinning parameters, respectively. 

Many parameters can influence the transformation of polymer solutions into nanofibers through electrospinning. These parameters include (a) solution properties, such as viscosity, elasticity, conductivity and surface tension (b) governing/operating variables, such as hydrostatic pressure in the capillary tube, electric potential at the capillary tip and the gap (distance between the tip and the collecting screen) and (c) ambient parameters such as solution temperature, humidity and air velocity in the electrospinning chamber. ... 

It is well known that many parameters, such as viscosity, elasticity, conductivity, surface tension and distance between tip and collection screen, can influence the transformation of polymer solutions into nanofibers through electrospinning. Solution viscosity is one of the most important factors. Since both polymers have significantly different molecular weights, four different solutions of N6,6 with various concentrations were prepared. We used a mixed solvent consisting of formic acid and chloroform with the ratio of 75/25 (v/v). Table 4.1 shows the solution viscosities for each concentration of low and high molecular weight N6,6. 

FIGURE 2.4 The electrospinning control parameters split into the cohorts of solution, processing, and ambient conditions. (Data from Haghi, A.K., ed.. Electrospinning of Nanofibres in Textiles, Apple Academic Press, Toronto, Ontario, Canada, 2011.)... 

SA. Therona, E. Zussmana, AL. Yarin. 2004. Experimental investigation of the governing parameters in the electrospinning of polymer solutions. T o/yffjer,45.pp.2017-30. 

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. 

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. 

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... 

Initial experiments to determine the suitable electrospinning parameters were carried out using P(3HB) alone in CHCI3 as the sole solvent. The morphology of films electrospun from different solution concentrations are shown in Fig. 6.2. 

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