The POLYFLOW system studies on the effect of flow conditions on the extrudate swell
Polimery 2002, No 2, 130
The POLYFLOW techniques were applied to model the polymer stream (Barrus effect,free surface problem) that leaves the shaping channel, e.g., an extruderhead, in an isothermal viscous and in a viscoelastic flow. The viscousNewtonian and generalized Newtonian (in terms of Bird-Carreau’s model) flowsand the viscoelastic flow were modeled, the latter by using the differentialMaxwell and the integral Kaye—Bernstein—Kearsley—Zapas (KBKZ) models. Extrudateswell was studied in relation to polymer flow rate, shaping-channel geometry,and material model (Figs. 6—9). Results were in fair agreement with experiment taldata. The simple (two-parameter) Maxwell equation proved to be the mostsuitable rheological equation to model the extrudate swell, except at high flowrates where some limitations arise.
Keywords: viscous flow, viscoelastic flow, isothermalconditions, extrudate swell, modeling, POLYFLOW system