Two types of MWCNT were used to make MWCNT-PDMS nanocomposite with electrical conductivity to be printed using an additive manufacturing technique for sensor applications.
- The first type of MWCNT: particles length of 5–20 μm, diameter 10–30 nm, and purity >85% (Industrial grade, NanoLab, Waltham, MA, USA).
- The second type of MWCNT: length 10 – 30 µm, diameter is 10 - 20 nm, and purity > 95%.
For the same experimental conditions, same PDMS-CNT wt%, and the same solvent used for dispersion, the 2nd type of MWCNT nanocomposite did not exhibit any electrical resistance and the viscosities of the two nanocomposites were different.
Does anyone have a suggestion as to why the MWCNT with a higher aspect ratio and higher purity does not present any electrical conductivity?
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Yes exactly. Due to the carbon atom's free electron located on it, the carbon nanotube will be electron conductive when is combined with polymer resin as a matrix and the parameter value measured about 49.49 S/cm. However, the activation energy(eV) will be decreased with increasing the MWCNTs concentration increase of MWCNTs concentration in pure polymer, this is may be due to changing the state of MWCNTs dispersion in the host polymer.
Riaz A. Khan Thank you for your response. Indeed, the diameter may also affect the final outcome, but in this case, the 2nd type of MWCNT has a better aspect ratio than the first type so, in theory, the electrical conductivity should be "better" than the first type (and that's also according to the literature), but that's not the case. That's what I can't seem to understand
Mahtab Ghasemi Toudeshkchouei Thank you for your response. To address your point about the concentration of MWCNT in the polymer host, I have actually tried different concentrations but it is always the same problem, there is electrical conductivity before curing the composite ( at 10 wt% PDMS-MWCNT) which disappears after the curing process.
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