I am using PAN with CNT for the electrospinning.I am using 13KV and 19cm distance,0.3ml/h speed.But during the eletcrospinning time sometime I am facing needle clogging.Fiber doesnot comes out from the needle.Sometimes the solution drop out from the needle but it doesn't makes any fiber.I have change the speed,voltage and distance.I am using silica to control the RH%.How to solve this problem.
Hi Farzana, in all my time studying electrospinning I never find a way to change this, what I usually do is changing the needle time to time, or wait it to drop anyway, and hope it don't goes to the metal.
Dear Farzana
Have you dispersed your CNT in DMF first?
It is known that CNT are in the form of aggregates whose size is relatively large. Then, the preparation of PAN/CNT dispersion in DMF is quite essential. The first think to do is to disperse CNT in DMF then to add PAN to CNT suspension in DMF.
A homogeneous PAN/CNT dispersion in DMF is a synergetic influence of two factors:
1. The reduction of CNT aggregate size due to the good dispersion of CNT in DMF (before adding PAN).
2. Once PAN is added, an effective mixing to prepare PAN/CNT dispersion in DMF is required.
Concerning the dispersion of CNT in low viscosity medium (e.g. DMF) can be achieved by two main approaches: Mechanical treatment (high shear mixing, ball milling, ultrasonication, etc.) or chemical modification of CNT (boiling in concentrated acids or using a surfactant).
Concerning the mixing, it depends on the used technique (stirring, high shear mixing, etc.) and the mixing time.
Personally, I use high shear mixing followed by ultrasonication to disperse MWNT in DMF, first. Then when adding PAN powder, I use a magnetic stirring for 24 h to get finally a homogeneous dispersion of PAN/MWNT in DMF.
I could easily electrospun this dispersion for at least 3 hours without any needle clogging!!
The needle that I use is a 22 G needle.
I may shear this article for further information!!
Best regards
Thank you so much Sliman Almuhamed for you suggestion.Please shear your article so that I can get more information.
Dear Farzana
To reduce the inconstant spinning I can recommend Slimans approach, since a heterogeneous solution is often the main cause for this behavior.
My favorite solution against the clogging is a Gas shield around the nozzle. This suppressed the evaporation of the spinning solvent, hence it allows to continuously electrospin highly volatile solutions like Dichloromethane or Chloroform solutions. [see Larsen et al 2004] With this you can spin for hours to days and you get more uniform fiber diameter because you maintain a stable Talyor cone.
Regards
Marc
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