Polymer-clay nanocomposites have generated considerable interest because of their improved mechanical, thermal, and physical properties at low clay loading as compared to conventional composites. My previous investigation revealed that nanocomposites of polyamide-6 with a moderate clay loading (5%), which had a 2-fold increase in tensile strength and modulus and a 100 °C increase in heat distortion temperature as compared to pure polymer. Since then, a significant amount of work has been reported on various polymer-clay nanocomposites based on polymers, such as polypropylene,4-6 polyamide 6,6,7 polystyrene, 8 poly (methyl methacrylate),9 poly (ethylene terephthalate), 10 and elastomeric polyurethane.

Polyurethane foams are a versatile class of polymeric materials. Flexible polyurethane foams are used as cushioning material with applications in furniture, automobiles, and packaging. Rigid polyurethane foams are primarily used for thermal insulation and structural applications. Polyurethane foams are prepared by the polymerization of a polyol with an isocyanate, in which the reacting mixture is foamed using one or more blowing agents. Polyurethane foams may have open or closed cells. Open cells are those in which the foam lamellae separating adjacent cells are all ruptured during the foam formation process. In closed cells, the lamellae remain intact.