INTERFACE DETERMINATION IN MULTILAYER EXTRUSION.

Coextrusion has become an attractive means of economically producing multilayered films and fibers. One of the major problems that this technology faces however is the control and prediction of the layer structure in the final product. The interface position not only affects the quality of the product but also can affect the die swell due to the different shearing history of the fluids. It is well established experimentally that in bicomponent flows there is a tendency of the low viscosity fluid to encapsulate the high viscosity fluid. Experiments indicate that major factor is the viscosity difference. In this work the authors examine the interface shape problem when two inelastic fluids are coextruded.