Broken Section Method for Analyzing Non-Newtonian Flow of Polymer Melts in Wire Coating Extrusion Die

Abstract It is proposed in this paper that non-Newtonian flow behavior of polymer melts in wire coating extrusion die can be analyzed theoretically by broken section method. It is assumed that the flow is steady, isothermal and laminar and the polymer melts behave as a power law fluid with flow index n. Further we assume that there occurs no slip at the boundaries. The polymer melts filled between die inside and wire surface are broken perpendicular to the flow axis into many sections, each of unit length. The materials in each section having different heights with the variation of the diameters of die, behave under combined pressure and drag flows of power law fluid. In this problem, the simultaneous equations on equal volumetric flow rate through each section can be formulated and hence the pressure distribution in the direction of wire axis can be obtained, for four cases where the relationships between drag flow and pressure flow are varied. The mathematical results are presented in detail for the cases of Newtonian flow (n = 1) and pseudoplastic flow (n = 1/2).