Domain Stability During Capillary Flow of Well Dispersed Two Phase Polymer Blends. Polystyrene/Polymethylmethacrylate Blends

Abstract

Hypotheses for domain stability, i.e. the conditions where each domain of a dispersed phase remains as a coherent domain during capillary flow is tested with data for polystyrene -polymethylmethacrylate melts. It is found that stable domains exist vhen the ratio between the (Trouton) zero shear viscosity of the dis-crete phase to the continuous phase is larger than approximately one. Blends of two thermodynamically incompatible polymers, polystyrene (PS) and poly(methyl-methacrylate) (PMMA), were melt blended in a Brabender Plasticorder over the compositions: 100$ PS, 75$, 50$ 25# and 0% PS. Viscous and die swell behaviour of pure polymers and the blends at different temperature were obtained using an Instron capillary rheometer and the microstructure of the melt blends was studied by transmission electronmicroscopy.