Polymer nanocomposites consisting of single-walled carbon nanotubes (SWCNTs) and poly(vinyl chloride) were prepared by casting technique. The complex viscosity increased with increasing SWCNTs content, and it had a percolation concentration threshold equal to 0.45 wt % of SWCNTs. The storage modulus, G', increased with increasing either SWCNTs content or frequency. A gradual decrease in the terminal zone slope of G' for the nanocomposites with increasing SWCNTs content may be explained by the fact that the nanotubenanotube interactions will be dominant at higher CNTs content, and lead to the formation of the interconnected or network-like structures of SWCNTs in the polymer nanocomposites. The rheological loss factor indicates two relaxation peaks at frequencies of 0.11 and 12.8 Hz due to the interaction between SWCNTs and polymer chains and glass transition, respectively. Dynamic mechanical properties were measured for the prepared composites. The results indicate that the storage modulus changes steadily, and the tand peaks are less intense for high SWCNTs content. Tensile tests were measured and depicted by an increase in the elastic modulus with increasing SWCNTs content, but it decreases for all composites as the testing temperature increased. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012