Processing, rheology and characterization of polypropylene nanocomposites and their blown films

Abstract

Polypropylene nanocomposites were melt blended and analyzed for both high shear and low shear rheology. Rheological characterization carried out at high shear rates showed lower viscosity values for the nanocomposites compared to the neat polypropylene. Complex viscosity values at low shear rates have shown an increasing trend on increasing nanoclay content. Zero-shear viscosity was found to increase with nanoclay loading. Steady rate sweep test results showed shear thinning of polypropylene and nanocomposites occurring in three steps. First normal stress difference showed higher values for 5 phr nanocomposite up to intermediate shear rate and subsequently lower values. Extensional viscosity experiments were carried out at different strain rates of 0.001, 0.01, 0.1 and 1 s−1. Polypropylene nanoclay samples showed better strain-hardening behavior compared to that in neat polypropylene. Polypropylene nanocomposites blown films prepared at different nip-roll speeds were characterized for their tensile properties and film in-homogeneity.