Morphological Evaluation of PP/PS Blends Filled with Different Types of Clays by Nonlinear Rheological Analysis

Abstract

The effects of various Cloisite nanoparticulate clays with different hydrophobicities on (80/20) polypropylene/polystyrene (PP/PS) blends were investigated using their linear and nonlinear rheological properties. In descending order of hydrophobicity the four Cloisite clays examined were C20A > C10A > C30B > CNa+. Clays with a wetting coefficient ωa of between 1 and −1, that is C20A and C10A, located at PP/PS polymer interfaces and suppressed coalescence, while clays with a ωa of >1, that is C30B and CNa+, accumulated inside the PS droplets and increased viscosity ratios. As a result, C20A and C10A caused PS droplet size reductions while C30B and CNa+ did not change morphology of the PP/PS blend. Linear rheological properties as determined by SAOS (small amplitude oscillatory shear) test and nonlinear rheological properties determined by LAOS (large amplitude oscillatory shear) test revealed C20A and C10A increased mechanical properties of PP/PS blends. Rheological properties from SAOS and LAOS tests decr...