Effect of organically modified layered silicate nanoclay on the dynamic viscoelastic properties of thermoplastic polyurethane nanocomposites

Different formulations of organically modified layered silicate (OMLS) clay based medical grade thermoplastic polyurethane (TPU) nanocomposites were successfully prepared via melt blending followed by compression molding. The effect of incorporation of nanoclay on the spherulitic morphology of the TPU matrix was studied with a polarizing optical microscope (POM). The exfoliation/intercalation of organoclay was attributed to the TPU-organoclay interaction and shear stress during melt mixing. The effects of clay content and degree of clay dispersion on the theological properties of nanocomposites were studied using a rubber process analyzer (RPA) with the help of dynamic strain, frequency, and temperature sweeps. The dynamic theological studies show that the complex viscosity (eta*) and dynamic storage modulus (G') of pristine TPU increased significantly with the incorporation of organoclay loading, which is attributed to the formation of an interphase between soft and hard segments of the TPU matrix and effective dispersion of the organoclay. (C) 2011 Elsevier B.V. All rights reserved.