Natural rubber nanocomposites were produced by melt-mixing of natural rubber with organically modified silicates. For comparison, a pristine-layered silicate and a nonlayered version [English Indian clay (EIC)] were also included in the study. The layered silicate used was sodium bentonite (BNT) and organoclays used were octadecylamine-modified montmorillonite (MMT-ODA) and methyltallow bis-2-hydroxyethyl ammonium-modified montmorillonite (MMT-TMDA). Accelerated sulfur system was used for the vulcanization of the nanocomposites. The dispersion of these silicates was studied by X-ray diffraction and transmission electron microscopy. The organoclay-incorporated composites exhibited faster curing and improved mechanical properties. The improvement in the mechanical properties of the composites followed the order MMT-ODA > MMT-TMDA > EIC > BNT. The property improvement was attributed to the intercalation/exfoliation of the organically modified silicates because of their high initial interlayer distance. (c) 2006 Wiley Periodicals, Inc.