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On-line vs off-line electrical conductivity characterization. Polycarbonate composites developed with multiwalled carbon nanotubes by compounding technology

: Llorens-Chiralt, R.; Weiss, P.; Mikonsaari, I.


Altstädt, V. ; American Institute of Physics -AIP-, New York:
29th International Conference of the Polymer Processing Society, PPS 2013. Proceedings : 15–19 July 2013, Nuremberg, Germany
New York, N.Y.: AIP Press, 2014 (AIP Conference Proceedings 1593)
ISBN: 978-0-7354-1227-9
Polymer Processing Society (PPS International Conference) <29, 2013, Nuremberg>
Fraunhofer ICT ()

Material characterization is one of the key steps when conductive polymers are developed. The dispersion of carbon nanotubes (CNTs) in a polymeric matrix using melt mixing influence final composite properties. The compounding becomes trial and error using a huge amount of materials, spending time and money to obtain competitive composites. Traditional methods to carry out electrical conductivity characterization include compression and injection molding. Both methods need extra equipments and moulds to obtain standard bars. This study aims to investigate the accuracy of the data obtained from absolute resistance recorded during the melt compounding, using an on-line setup developed by our group, and to correlate these values with off-line characterization and processing parameters (screw/barrel configuration, throughput, screw speed, temperature profile and CNTs percentage). Compounds developed with different percentages of multi walled carbon nanotubes (MWCNTs) and polycarbonate has been characterized during and after extrusion. Measurements, on-line resistance and off-line resistivity, showed parallel response and reproducibility, confirming method validity. The significance of the results obtained stems from the fact that we are able to measure on-line resistance and to change compounding parameters during production to achieve reference values reducing production/testing cost and ensuring material quality. Also, this method removes errors which can be found in test bars development, showing better correlation with compounding parameters.