Viscoelastic properties of multiwalled carbon nanotube solutions

We have prepared solutions of multiwalled carbon nanotubes in very low vapour pressure solvents (a mixture of chlorinated biphenyls). The solutions are stable and show no sign of precipitation for six months. Rheological measurements using a modified Birnboim apparatus with annular and Sogel-Pochetino geometries have been performed. Using time-temperature superposition we obtained the real and imaginary part of the complex viscosity coefficient in a frequency range covering eight orders of magnitude and a temperature range from 5 to 50 <Superscript>○</Superscript>C. The data shows unexpected changes in the solution with temperature: for T below 30 <Superscript>○</Superscript>C there appears to be some reorganization or clustering. This self-organization could result in a useful technique to improve the electronic properties of polymer/carbon nanotubes composites used in organic electronic devices. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006