화학공학소재연구정보센터
Journal of Polymer Science Part B: Polymer Physics, Vol.52, No.1, 73-83, 2014
Aspect Ratio Effects of Multi-walled Carbon Nanotubes on Electrical, Mechanical, and Thermal Properties of Polycarbonate/MWCNT Composites
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 approximate to 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 approximate to 100. Because of the molecular weight reduction glass transition temperatures predictably show a large decrease with increasing nanotube concentration. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 73-83