Hi,
I am a master student doing my master thesis in "Textile Engineering" in Sweden. My project is based on producing "Highly conductive and Highly flexible polymer filaments". I am mixing Thermoplastic polyurethane(TPU) with Multi walled carbon nano tubes(MWCNT) using twin screw micro compounder(melt extrusion). I had extruded 3mm MWCNT filled TPU filaments. I had used MWCNT vol% of 0.57 and 0.85. I have doubts regarding how to find the percolation threshold values. It will be of great help if you can give me some valuable suggestions. Thank you for your time in advance.
Regards,
Vignesh.
Hi Vignesh,
have you done some literature searching? Measuring percolation thesholds for CNTs in polymers is a well-known thing. It may take a little while to find a paper where the technique is well-described (I assume it is the technique that you have doubts about and I assume that you already have values from literature for CNT-TPU to compare with)
This reference seems to describe work very similar to what you're doing (melt extrusion, twin screw, MWNT-TPU, 3mm diameter fibres)
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.582.1656&rep=rep1&type=pdf
it seems they needed 3-4% loading in filaments to get to the percolation threshold (but a lower value in films)
It is from Ton Petjes group at Queen Mary University of London - this is a group who does a lot of this type of work, it would be worth having a look at Ton's publication list for other useful references.
Hi Fiona smail,
Thank you for sharing the article, Yes i had read similar articles like the one you shared. Where they had used a formula
σ =σ0( p − pc) t for finding percolation threshold.
Where i dont know to fix the 't' value and i dont know what is σ0. Thank you.
There is no universal percolation limit in CNT filled polymer composites. It depends on measurement technique, ex: electrical, mechanical, rheological etc. Petra Pötschke of Leibniz institute has done tremendous work on this topic.. especially this paper is worth mentioning. doi.org/10.1016/j.eurpolymj.2010.02.009
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