The effect of vinyl acetat (VA) on the morphological, thermal stability, and mechanical properties of heterophasic polypropylene(ethylene-propylene) copolymer (PPEP)/poly(ethylene vinyl acetate) (EVA)/organoclay nanocomposites was studied. Tailored organoclay C20A was selected to enhance the exfoliation of the clay platelets. Depending on the VA content, there were two morphological organoclay populations in the systems. Both populations were directly observed by scanning transmission electron microscopy and measured by wide-angle X-ray diffraction and small-angle X-ray scattering. The content of VA in EVA originated spherical and elongated morphologies in the resultant nanocomposites. High-VA content led to a better intercalation of the organoclay platelets. Measurement of thermal properties suggested that higher VA decreases thermal stability in samples both with and without organoclay, although nanocomposites had higher thermal stability than samples without clay. The storage modulus increased both with nanoclay and VA content. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013