To improve the chemical, physical, and mechanical properties of polyvinyl acetate (PVAc), an organic montmorillonite (OMMT) was first prepared by montmorillonite (MMT) and octadecyl trimethyl ammonium bromide (STAB), and then it was added to synthesized PVAc under conventional laboratory conditions. The influence of its variable addition on the properties of PVAcOMMT was investigated mainly by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and static tension, and the rheology was also investigated by the power-law function equation and the CrossWilliamson model viscous equation. The exfoliated nanocomposite of PVAcOMMT was obtained; linear macromolecular chains of PVAc were formed in the layers of OMMT, and no chemical bonding appeared between OMMT and PVAc, but there were some physical effects. The dispersion of PVAcOMMT was better than PVAc. OMMT was exfoliated into layers or sheets of nanoparticles and was randomly dispersed in the matrix of PVAc. The particle diameter of OMMT ranged from 50 to 100 nm, whereas PVAc's diameter ranged from 250 to 500 nm; the smaller OMMT particles were adsorbed around the bigger all PVAc particles and formed a strawberry structure. PVAc and PVAcOMMT were both pseudoplastic non-Newtonian fluids; they possessed the normal stress effect (or the Weissenberg effect), that is the pole-climbing phenomenon. The static tension properties of PVAcOMMT were much better than PVAc, and the addition of OMMT in polymerization was reasonable and not more than 2.0% of VAc. (c) 2011 Wiley Periodicals, Inc. Adv Polym Techn 32: 130140, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20244