Large amplitude oscillatory shear of immiscible polymer blends and comparison to anisotropy and droplet models

Large amplitude oscillatory shear (LAOS) experiments were carried out for a model immiscible blend composed of two Newtonian components at different viscosity ratio and volume fraction values. Data for the first, third, and fifth harmonics of the sinusoidal stress response were recorded and compared to the constrained volume (CV) model and to the Maffettone and Minale model. Moreover, various constitutive equations were investigated: The Batchelor constitutive equation with the viscous part of the interfacial contribution to stress neglected, Peters et al. [J. Rheol. 45, 659-689 (2001)] constitutive equation, the Lee and Park [J. Rheol. 38, 1405-1425 (1994)] constitutive equation, and the Yu and Bousmina [J. Rheol. 47, 1011-1039 (2003)] constitutive equation. It was found that a modification of the Peters et al constitutive equation, when combined with the CV model predictions, results in good description of the first harmonic data, as well as reasonable description for the third and fifth harmonic data. Experimental LAOS results at large viscosity ratio agreed well with the scaling law developed by Reinheimer et al. [J. Colloid Interface Sci. 360, 818-825 (2011)]. (C) 2014 The Society of Rheology.