I tried to fabricate carbon nanofibers by electrospinning PAN and treating it at 400°C for 1 hr (as it was reported in literature to obtain carbon nanofibers). PAN nanofibers turned to black, they were brittle and of course not conductive.
Can anyone sugges what is the problem of my work? Is it because I got oxygen in the furnace which burned the fibers, or maybe I have to keep the samples in the furnace for more hours to get the conductivity? Conductivity and flexibility are both important for me.
Thank you so much for your answer.
There is still a question remained for me. Does oxidation and carbonization has to occur continuously or there can be proceeded separately. I mean Is it OK if I put the PAN samples in a furnace under the air conditions (for example for an hour). then take it out and put it to another furnace under inert conditions .
what happens chemically if I ignore the first step(oxidizing)? I would appreciate it if you suggest me a reference in literature about it
Dear Dr Meyer-Plath
I read the article. and it really helped me to understand the process.
Thank you so much for your help
Dr. Meyer-Plath,
I've stabilized my PAN fibers in air at 280 C. During the carbonization stage, when using inert gas, should the vacuum pump be on the entire heating phase?
I've tried with high vacuum (pressure
I see. The pressure before starting the gas flow is 0.3 mbar and reached up to 20 mbar. Might be due to some leak in the system which constantly sucks in air.
Say for a closed system, I start the pump for approx 10 mins to suck away the air and then turn off the pump, after that allow the N2 gas to fill my tube furnace during heating. WIll it be better this way, since I can't probably improve the my vacuum system?
Thanks for your input.
Dear Farnaz,
typically polyacrylonitrile forms heteroaromatic rings and crosslinks in air with itself. This stabilization process is necessary to make the fibre unmeltable. After this step the fibre can be carbonized in nitrogen.
First of all you should find out the correct stabilisation temperature. This differs and is dependent by the polyacrylonitrile type. Try to perform a DSC (Differental Scanning Calorimetry) measurement of your fiber in air at 5°C/min. If you tell me the temperature of the peak start and the peak maximum, I can give you some proposals to perfom the stabilisation reaction at suitable temperature.
After doing the correct stabilisation you can perform the carbonisation step up to 1200 to 1500 °C in nitrogen with no problems.
Best regards
Michael
Asmus A. Meyer-Plath
Dear Sir,
I have synthesized Polyacrylonitrile fibers on aluminum foil using the electrospinning technique. I have to convert that fiber into carbon fibers so that I have to do carbonization of those fibers at around 950 degrees celsius. I have to use that carbon fibers as a supercapacitor electrode.
For finding out capacitance I have to use that electrode as a working electrode in the cyclic voltammetry test.
My questions are-
1. Can I put that fiber mat with aluminum foil in the furnace ??..... I think foil will burn
2. If I peel off that fiber mat from aluminum foil and keep in the furnace then I will require to crush that fiber using a mortal piston. now I will require to deposit that crushed active material on some substrate so that i can use that as a working electrode in the cyclic voltammetry test. To deposit that material I will require a binder without which that material will not get deposit on that substrate. now that substrate with deposited material will act as an electrode and I can do the CV test.
So can you suggest binder and substrate material? or do you suggest any other method for preparation of electrode.
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