Stratified two-phase flow of molten polymers

A study has been made of stratified two-phase flow of molten polymers in a slit die. For the experimental study, measurements were taken of wall normal stresses along the longitudinal axis of a rectangular duct which had an aspect ratio of 10. Three pressure transducers were flush-mounted on each of the rectangle's long sides, directly opposite from each other. The measurements permitted one to determine the pressure gradients of each component (their viscous properties) and the exit pressures of each component (their elastic properties). For the theoretical study, the fully developed velocity distributions of two-phase flow were determined by solving the equations of motion by use of a power law model. The volumetric flow rates, calculated theoretically by use of a power law model, are compared with experimentally observed ones. Experimental evidence is presented which clearly shows that polystyrene and polypropylene form two incompatible phases in the molten state.