Multiwalled carbon nanotubes (MWNTs) with two different diameters were dispersed within poly( is an element of-caprolactone) (PCL) by melt-blending and coprecipitation, respectively, with the purpose to impart good electromagnetic interference shielding properties to the polyester. Transmission electron microscopy showed that the MWNTs were uniformly dispersed as single nanotubes within the matrix. Because the nanotubes were broken down during melt-blending, the percolation threshold was observed at a lower filler content in the case of coprecipitation. Substitution of poly(ethylene-co-octene), poly( vinyl chloride), polypropylene, and polystyrene for PCL resulted in a much lower shielding efficiency. Finally, polycarbonate and poly( methyl methacrylate) appeared as promising substitutes for PCL, suggesting that pi-pi interactions between the nanotubes and constitutive carbonyl units of the polymers would be beneficial to the dispersion and ultimately to the electrical properties of the nanocomposites.
