Cocontinuous polymer blends: influence of viscosity and elasticity ratios of the constituent polymers on phase inversion

The morphological properties of melt-mixed blends with cocontinuous phase morphology composed of poly(methyl methacrylate) and polystyrene or poly(styrene–co–acrylonitrile) are studied. By means of digital image analysis of two-dimensional TEM pictures the mean form factor ffirr was established as a classificator. For 11 blend systems phase inversion concentrations were determined in this way. died the influence of viscosity and/or elasticity ratios on the phase inversion concentration. Most theories based on viscosity ratio disagree with our experimental data. The analysis of corresponding phase inversion concentrations based on elasticity ratio determined at a constant shear stress leads to a simple and good correlation.