Silane-grafted high-density polyethylene (HDPE-g-Si) was prepared by reactive extrusion. The grafted polyethylene (PE) was then melt compounded with organically modified montmorillonite and polyamide-6 (PA6) to form ternary nanocomposite. Fourier Transfer Infrared was used for investigation of grafting efficiency of specimens. Dispersion of clay in the blends and individual polymers were examined by X-ray diffraction (SAXS) and transmission electron microscopy (TEM). Scanning electron microscopy and dynamic rheology were also used for further study of microstructure along with compatibilization effect of silane grafting and adding organoclay in the blends. SAXS and TEM study showed that nanoclay was delaminated by PA6 or HDPE-g-Si chains, whereas the intercalation of neat HDPE in clay layers was negligible especially in higher level of clay. The morphological studies indicated that silane-grafted HDPE had hydrophilic characteristics and, therefore, was more compatible with PA6 than neat PE. Furthermore, in the same way adding nanoclay to this blends resulted in more uniform and finer morphology. And finally, results of oxygen and hydrocarbon permeability measurement demonstrated synergetic effect of silane grafting and presence of clay on barrierity improvement of samples. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013