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1. Uy, Jamieson Clark T.

2. Electrospinning Uses an electrical charge to draw very fine fibres from a liquid. This method ensures that no solvent can be carried over into the final product. Ability to produce novel synthetic fibers of small diameter and good mechanical properties.

3. Advantages Inexpensive and simple method Capable of producing nanofibers positive terminal negative terminal

4. Advantages Able to make very thin fibers easily, since the viscosity of many polymer solutions is very low. The lower viscosity of sample makes an elongational deformation easily.

5. Disadvantages The instability of elongational deformation increases with growing deformation of low viscosity polymer solutions. Beads are more easily formed as the fiber diameter decreases. Beads formation decreases the surface area of fabrics

6. Process Electrospinning: A high voltage is passed through a polymer solution inducing an electrostatic repulsion force The polymer is pumped through an insulin syringe, the repulsion force results in the formation of a thin jet This jet is directed toward a grounded collection plate, the solvent evaporates before hitting the collection plate and results in the formation of a polymer scaffold

7. Fiber dimension and morphology The diameter of a fiber produced by electrospinning primarily depends on the spinning parameters. An increase in solution concentration results in fibers with larger diameters.

8. Parameters With increasing concentration of the fiber content, increase in mechanical properties. But further increasing it, mechanical properties drops. With increasing electric potential the fiber diameter decreases, and the fiber diameter distribution becomes increasing broader.

9. Parameters 1. Molecular Weight of the polymer2. Solution properties (viscosity, conductivity and surface tension)3. Electric potential, flow rate and concentration4. Distance between the capillary and collection screen5. Ambient parameters (temperature, humidity and air velocity in the chamber)6. Motion of target screen (collector)

10. 2 main Properties of fibers produced A very high surface to volume ratio Defect free structure at the molecular level

11. Model of Surface-to-Volume Comparisons… Single Box Ratio 6 m2 1 m3 = 6 m2/m3 Smaller Boxes Ratio 12 m2 1 m3 = 12 m2/m3 Neglecting spaces between the smaller boxes, the volumes of the box on the left and the boxes on the right are the same but the surface area of the smaller boxes added together is much greater than the single box.

12. Nanofiber Structures Interconnected structure (Source: Ramakrishna, S., et.al, 2005)

13. Filtration Polymeric nanofibers have significant applications in the area of filtration since their surface area is substantially greater and have smaller micropores than any other fibers like spun bond and melt blown (MB) webs.