Synthesis and Properties of Polyurethane-Vermiculite Nanocomposites

Natural vermiculite was modified by cation exchange with long-chain quaternary alkylammonium salts and then dispersed in a polyether-based polyol suitable for elastomeric polyurethane synthesis. The dispersions were evaluated by X-ray scattering and rheology. Polyol was intercalated into the vermiculite interlayer space and a large interlayer spacing of ~90 Å was achieved. Significant shear thinning behavior was also observed. In polyurethane composites, clay platelets were extensively intercalated or exfoliated. The composites showed a >270% increase in tensile modulus, >60% increase in tensile strength, and a 30% reduction in N2 permeability with a loading of 5.3 wt% clay in polyurethane.