Effect of die temperature on the flow of polymer melts. Part I: Flow inside the die

Abstract

The effect of die wall temperature on the flow of polymer melts in circular capillary dies was studied. At constant flow rates, it was found that die wall temperature had a greater effect on the pressure drop than melt temperature. A capillary die with two circular channels with different diameters was designed to simulate the profile extrusion. Changes of wall temperature varied the flow rate ratio between the two channels. An implicit finite difference method was used to simulate the velocity and temperature profiles inside the die. Values predicted by this model matched well with experimental data for both dies.

Computer‐aided geometric design of the preform dies for flat film extrusion through 3‐D finite element flow analysis

“…There are also some aspects, such as the elastic properties and the viscous dissipation, which require further consideration. However, under normal operating conditions, the velocity distributions of the flow of polymer melts in flat dies remain parabolic: and they are not very different from the isothermal flow (26,27). In the future we will seek to generalize the present procedure to a more realistic flow model, which will take into account both effects of the polymer melts.…”

Design Feature Sensitivity Analysis in Numerical Modeling of Extrusion Spider Dies

“…The temperature of the die wall is kept at a constant value, T w =469K and the volumetric flow rate of the melt is fixed at 6 3 max 7,9 10 / sec The numerical solution assumes that, a homogeneous and isotropic HDPE melt with a uniform temperature of T=469K is flowing into the spider die.…”

“…CFD-based approaches have been developed previously by other researchers to study various aspects of flow in extrusion dies [5,6]. For this purpose, a computational fluid dynamics (CFD) based model using the generalized Newtonian approach was employed, to investigate pressure drop, flow and temperature uniformity in the die.…”

Process control of profile extrusion using thermal method. Part I: Mathematical modeling and system analysis

“…Equation 15 is compared with experimental data obtained from a n Instron capillary rheometer with a modified die section (10). The power-law index, R , for the polystyrene melt used was predetermined as 0.28 from the rheological characterization ( 1 0).…”

“…This value is used to predict the pressure drop difference at different flow rates for all nonisothermal cases studied in ReJ. 10. The same @ is also used to predict the pressure drop difference resulting from a short die (LID = 20).…”