Journal of Polymer Science Part B: Polymer Physics, Volume 52, Issue 1, pages 73–83, 1 January 2014.
Jiaxi Guo1, Yanjun Liu1, Ricardo Prada-Silvy2, Yongqiang Tan2, Samina Azad2,Beate Krause3, Petra Pötschke3 , Brian P. Grady1,
School of Chemical, Biological & Materials Engineering, University of Oklahoma, Norman, Oklahoma.
- SouthWest NanoTechnologies Inc. (SWeNT), Norman, Oklahoma.
- Leibniz Institute of Polymer Research Dresden (IPF), Dresden, Germany.
Two multi-walled carbon nanotubes (MWCNTs) having relatively high aspect ratios of 313 and 474 with approximately the same diameter were melt mixed with polycarbonate (PC) in a twin-screw conical micro compounder. The effects of aspect ratio on the electrical, mechanical, and thermal properties of the PC/MWCNT composites were investigated. Electrical conductivities and storage moduli of the filled samples are found to be independent of the starting aspect ratio for these high aspect ratio tubes; although the conductivities and storage moduli are still significantly higher than values of composites made with nanotubes having more commercially common aspect ratios of ∼100. Transmission electron microscopy results suggest that melt-mixing reduces these longer nanotubes to the same length, but still approximately two times longer than the length of commercially common aspect ratio tubes after melt-mixing. Molecular weight measurements show that during melt-mixing the longer nanotubes significantly degrade the molecular weight of the polymer as compared to very similar nanotubes with aspect ratio ∼100. Because of the molecular weight reduction glass transition temperatures predictably show a large decrease with increasing nanotube concentration. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 73–83
Copyright © 2013 Wiley Periodicals, Inc.