Styrene maleic anhydride copolymer (SMA) encapsulated single wall carbon nanotubes (SWNT) are melt mixed with PA12 in order to disperse SANT more homogeneously. The mechanism is found to be a reactive coupling between amine end groups of PA12 and maleic anhydride functionality of SMA during melt mixing of PA12 with SMA modified SWNT. This leads next to a better dispersion to an enhanced interfacial adhesion between PA12 and SWNT as indicated by enhanced rheological, dynamic mechanical, and tensile properties of the PA12/SWNT composites. (C) 2004 Elsevier B.V. All rights reserved.