working principles of electrospinning

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By: bolwriekbell (39 month(s) ago)

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WORKING PRINCIPLE OF ELECTRO SPINNING:

WORKING PRINCIPLE OF ELECTRO SPINNING PRESENTED BY: RAHUL SHARMA M PHARM(PHARMACEUTICS) 4 TH SEM

Electrospinning set up:

Electrospinning set up

SET UP:

SET UP 1)High voltage power supply (KV) 2) Syringe ( elecrode ) through which the polymer solution flows. 3) Infusion pump: provide a constant flow of solution at the tip of the syringe. 4) Target onto which fibers are collected.(called collector)

Electrospinning:

Electrospinning This process involves the ejection of a charged polymer fluid onto an oppositely charged surface . Infusion pump maintains the flow of polymer. High potential occurs at tip of the syringe from which taylor cone forms and eventually the nano fibers.

WORKING:

WORKING

Taylor cone:

Taylor cone

TYPES OF PROCESSES:

TYPES OF PROCESSES VERTICAL SET UP

PowerPoint Presentation:

HORIZONTAL SET UP

ELECTROSPINNING PARAMETERS:

ELECTROSPINNING PARAMETERS PROCESS PARAMETERS Applied voltage Flow rate Capillary collector distance SOLUTION PARAMETERS Polymer concentration or viscosity Solution conductivity Solvent volatility TYPE OF ELECTROSPINNING NOZZLE CONFIGURATION single side by side co axial SOLUTION VS MELT ELECTROSPINNING

Process parameters:

Process parameters 1. Applied voltage The strength of the applied electric field controls formation of fibers . Suboptimal field strength could lead to BEAD DEFECTS or even failure in jet formation Increase in applied voltage alters the shape of the surface at which the Taylor cone and fiber jet a re formed . At lower applied voltages the Taylor cone is formed at the tip of the pendent drop; however, as the applied voltage i s increased the volume of the drop decreases until the Taylor cone was formed at the tip of the capillary, which was associated with an increase in bead defects seen among the electrospun fibers.

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Figure 4: Effect of varying the applied voltage on the formation of the Taylor cone T here is an optimal range of electric field strengths for a certain polymer/solvent system, as either too weak or too strong a field will lead to the formation of beaded fibers

2. Flow rate:

2. Flow rate cone shape at the tip of the capillary cannot be maintained if the flow of solution through the capillary is insufficient to replace the solution ejected as the fiber jet . Megelski et al demonstrated that both fiber diameter and pore size increase with increasing flow rate . Flow rate impacts on:

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At high flow rates significant amounts of bead defects are noticeable, due to the inability of fibers to dry completely before reaching the collector. Incomplete fiber drying also leads to the formation of ribbon like (or flattened) fibers as compared to fibers with a circular cross section. RIBBON LIKE FIBER DEFECTS

3. Capillary collector distance:

3. Capillary collector distance

SOLUTION PARAMETERS:

SOLUTION PARAMETERS

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Solution parameter contd ….

2. SOLVENT VOLATILITY:

2. SOLVENT VOLATILITY

3. SOLUTION CONDUCTIVITY::

3. SOLUTION CONDUCTIVITY:

TYPES OF ELECTROSPINNING :

TYPES OF ELECTROSPINNING

c. Co axial:

c. Co axial

2. Solution vs. melt electrospinning:

2. Solution vs. melt electrospinning

REFERENCES:

REFERENCES

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"What we observe is not nature itself, but nature exposed to our method of questioning."---- Werner Heisenberg

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