Non-isothermal extrudate swell

The non-isothermalextrudate swell of a high molecular weight high-density polyethylene (HDPE) in long capillary and slit dies is studied numerically (ANSYS POLYFLOW®) using an integral K-BKZ constitutivemodel includingcrystallization kinetics, determined experimentally. The Nakamuramodel is used forcrystallization of the HDPE, where thecrystallization rate parameter is evaluated by using the well-known Ziabickiequation. This non-isothermalextrudate swell phenomenon is simulated using the pseudo-time integral K-BKZmodel with the Wagner damping function along with the differential form of the Nakamuramodel to account for thecrystallization of the extrudate. The swell measurements were carried out under non-isothermal conditions by extruding thepolymer melt at 200  °C through long capillary and slit dies to ambient air at 25 °C, 110 °C, and 200 °C. The numerical results are found to be in excellent agreement with experimental observations.

Source: Physics of Fluids - December 8, 2016 Category: Physics Authors: Vinod Kumar Konaganti, Maziar Derakhshandeh, Marzieh Ebrahimi, Evan Mitsoulis and Savvas G. Hatzikiriakos Source Type: research