Bicomponent flow of molten polymers in annular dies of extruders

Presented are the approximate and exact solutions of the problem of a combined flow of two non-Newtonian fluids having rheological properties described by a power law though a slit channel. This problem is encountered in the design of calibrating dies for extrusion of bicomponent films. The calculation results have been applied to the description of operation of two extruders feeding the same die in the production of bicomponent films. The calculation results have been applied to the description of operation of two extruders feeding the same die in the production of bicomponent films from two polymers pertaining to the same class and having different viscosities at a predetermined ratio of layer thicknesses. The calculation values obtained have shown to be in a good agreement with experimental results for co-extrusion of polypropylene grades having different melt indices.