The transient shear and extensional properties of ethylene vinyl acetate nanocomposites containing two geometrically different nanoparticles (spheres of CaCO3 and platelet of clay) were investigated experimentally and the data were compared to the rheological predictions of the modified molecular stress function (MSF) theory as recently proposed by Abbasi [Rheol. Acta 51, 163-177 (2012)]. While good agreement was obtained for spherical particles, deviations were observed for platelet particles at concentrations higher than 2.5 wt. %. The limitation of MSF theory for such compositions was related to the domination of the linear rheological response by the presence of particle nanonetworks over polymeric chains' contribution. This particle network contribution was also found to increase nonlinearity under large deformation, a phenomenon which was quantified via Fourier transformed rheology on data obtained under large amplitude oscillatory shear. (C) 2013 The Society of Rheology. [http://dx.doi.org/10.1122/1.4798559]