Rheological properties of the solutions of incompatible polymer blends

Abstract

In this paper, viscosity profiles of solutions of blend polymers were studied. These solutions were made up with incompatible polystyrene and poly(methyl methacrylate) in chloroform as a cosolvent. A totational viscometer was used to obtain the viscosity data. And the data were analyzed by using the Ree-Eyring flow equation. The parameters in the Ree-Eyring equation could be expressed as fuctions of blending ratio $\chi$. The activation free energy for flow of a blend system is expressed by a combination of the activation free energies of the component polymers. Thus $\beta_{i,b1}$ which is proportional to the relaxation time of the ith flow unit of the blend system, can be expressed as an exponential fuction of $\chi$. Another parameter $(1/\alpha)_{1,b1}$ which is the intrisic shear stress of the ith flow unit, can be expressed by a linear combination of 1/$\alpha_i$ for each component in terms of $\chi$. And a remaining parameter $x_{i,b1}$ the area fraction occupied by the ith flow unit in the blend system, can also be expressed by a linear combination of $x_i$ for each component in terms of $\chi$. Introducing these considerations, we derived a new viscosity equation for the blend system. The experimental data of $\eta_{b1}$ were compared with the calculated $\eta_{b1}$ values with good results. This equation can also explain very well such a phenomenon that shows constant viscosities over the low shear rate region for high blending ratio of poly(methyl methacrylate).