| Abstract: | Linear viscoelastic behaviors of ethylene‐vinyl acetate (EVA)‐layered silicate nanocomposites were investigated. EVA with vinyl acetate (VA) content of 18 and 28% by weight and commercially modified montmorillonite clay (Cloisite® 30B) were melt blended in a twin‐screw extruder. Nanocomposites of 2.5, 5 and 7.5% by weight were produced. Wide angle X‐ray scattering was used to ascertain the degree of layer swelling that could be attributed to the intercalation of polymer chains into the interlayer of the silicates. Transmission electron microscopy was used to analyze the dispersion and extent of exfoliation of the layered silicates in the polymer matrix. All nanocomposites were found to have mixed intercalated/exfoliated morphologies. Both storage and loss moduli and complex viscosity showed improvement at all frequencies tested with increase in silicate loading. Terminal zone behavior was also shown to disappear gradually with silicate content. Increase in silicate loading had caused the divergence of viscosity profile from low‐frequency Newtonian plateau to non‐Newtonian slope corresponding to a possible finite yield stress. The gradual disappearances of terminal zone and Newtonian homopolymer‐like characteristics with silicate loading were attributed to the formation of lattice spanning three‐dimensional network structures. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2127–2135, 2006 |
