Nanotube Networks in Polymer Nanocomposites: Rheology and Electrical Conductivity

@article{du02, abstract = {Abstract: Single-walled carbon nanotube (SWNT)/poly(methyl methacrylate) (PMMA) nanocomposites were prepared via our coagulation method providing uniform dispersion of the nanotubes in the polymer matrix. Optical microscopy, Raman imaging, and SEM were employed to determine the dispersion of nanotube at different length scales. The linear viscoelastic behavior and electrical conductivity of these nanocomposites were investigated. At low frequencies, G' becomes almost independent of the frequency as nanotube loading increases, suggesting an onset of solidlike behavior in these nanocomposites. By plotting G' vs nanotube loading and fitting with a power law function, the rheological threshold of these nanocomposites is ~0.12 wt \%. This rheological threshold is smaller than the percolation threshold of electrical conductivity, ~0.39 wt \%. This difference in the percolation threshold is understood in terms of the smaller nanotube-nanotube distance required for electrical conductivity as compared to that required to impede polymer mobility. Furthermore, decreased SWNT alignment, improved SWNT dispersion, and/or longer polymer chains increase the elastic response of the nanocomposite, as is consistent with our description of the nanotube network.}, address = {Department of Chemical and Biomolecular Engineering and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104}, author = {Du, F. and Scogna, R. C. and Zhou, W. and Brand, S. and Fischer, J. E. and Winey, K. I. }, citeulike-article-id = {2802678}, doi = {10.1021/ma049164g}, journal = {Macromolecules}, keywords = {nanocomposite, nanotube, polymer, rheology}, month = {November}, number = {24}, pages = {9048--9055}, posted-at = {2008-05-15 21:58:35}, priority = {2}, title = {Nanotube Networks in Polymer Nanocomposites: Rheology and Electrical Conductivity}, url = {http://dx.doi.org/10.1021/ma049164g}, volume = {37}, year = {2004} }

TY - JOUR ID - du02 L3 - citeulike-article-id:2802678 TI - Nanotube Networks in Polymer Nanocomposites: Rheology and Electrical Conductivity JF - Macromolecules VL - 37 IS - 24 SP - 9048 EP - 9055 AD - Department of Chemical and Biomolecular Engineering and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 N2 - Abstract: Single-walled carbon nanotube (SWNT)/poly(methyl methacrylate) (PMMA) nanocomposites were prepared via our coagulation method providing uniform dispersion of the nanotubes in the polymer matrix. Optical microscopy, Raman imaging, and SEM were employed to determine the dispersion of nanotube at different length scales. The linear viscoelastic behavior and electrical conductivity of these nanocomposites were investigated. At low frequencies, G' becomes almost independent of the frequency as nanotube loading increases, suggesting an onset of solidlike behavior in these nanocomposites. By plotting G' vs nanotube loading and fitting with a power law function, the rheological threshold of these nanocomposites is ~0.12 wt %. This rheological threshold is smaller than the percolation threshold of electrical conductivity, ~0.39 wt %. This difference in the percolation threshold is understood in terms of the smaller nanotube-nanotube distance required for electrical conductivity as compared to that required to impede polymer mobility. Furthermore, decreased SWNT alignment, improved SWNT dispersion, and/or longer polymer chains increase the elastic response of the nanocomposite, as is consistent with our description of the nanotube network. KW - nanocomposite KW - nanotube KW - polymer KW - rheology AU - Du, F AU - Scogna, RC AU - Zhou, W AU - Brand, S AU - Fischer, JE AU - Winey, KI PY - 2004/11/30/ UR - http://dx.doi.org/10.1021/ma049164g ER -