Abstract
The velocity distribution along the axis of a low-density polyethylene (LDPE) melt strand extruded through an axisymmetric capillary and drawn by various forces is simulated using an integral constitutive equation with a PSM damping function (Papanastasiou, Scriven, Macosko, Journal of Rheology, 27: 381–410, 1983). The simulations are performed for different drawdown forces of the strand. The numerical results are compared with experimental data obtained by velocity measurements using the laser-Doppler velocimetry. The strand is drawn by rotating wheels as used in a Rheotens™ testing device. At drawdown forces greater than zero the investigations show that the strand velocity does not increase linearly with increasing distance from the die exit. Instead, it is observed that the acceleration of the strand increases monotonically. Except in the next vicinity of the die exit there is a good agreement between simulation and experiment. However, near to the die the simulation predicts a higher strand velocity.
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Schneider, C., Schwetz, M., Münstedt, H. et al. The Axial Velocity Distribution of a Polyethylene Strand During Extrusion: Simulation and Comparison with Measurements. Mechanics of Time-Dependent Materials 8, 215–224 (2004). https://doi.org/10.1023/B:MTDM.0000046795.16699.b8
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DOI: https://doi.org/10.1023/B:MTDM.0000046795.16699.b8