This article presents a process for preparing organovermiculite by ball-milling expanded vermiculite (EVMT) in waterbased ethylene vinyl acetate (EVA) latex. In this process, the vermiculite (VMT) is exfoliated to prepare a kind of EVMT/EVA modifying agent, in which EVA serves as both intercalating polymer into VMT and compatibilizer between VMT and polypropylene (PP). During melt blending between EVMT/EVA and PP, shear force exfoliates VMT sheets, dispersing them relatively well in the PP matrix. Compared with raw PP, EVMT-modified cast polypropylene (CPP) are better when EVMT loading ranged from 0.5 to 1.0%, with improvement in both the strength and toughness of the EVMT/EVA-modified CPP film. Specifically, tensile strength was increased by 44-54%, yield stress increased by 26%, stress at break increased by 37-43%, energy at break (toughness) increased by 29-34%, oxygen transmission rate decreased by 6.2-12.9%, the water vapor transmission rate was not significantly affected, the peel bond strength of laminated CPP film increased by 18-27%, and the processability and melt flow index (MFI) of EVMT/EVA/PP composites were improved as well. Increasing MFI attributes facilitated the processing and formation of EVMT/EVA/PP. V C 2014 Wiley Periodicals, Inc. J.Appl. Polym. Sci. 2014, 131, 40954.