Numerical Simulation of Crystallinity Distribution Developed In the Extrusion of Thick Walled Polypropylene Pipe

R. D. Wilcox1, and J. Collier2
1Chemistry Department, Lincoln Memorial University, Harrogate, TN, USA
2Chemical Engineering Department, Florida State University, Tallahassee, FL, USA

In a numerical simulation for crystallinity distribution, a 36 cm diameter polypropylene pipe with 3.7 cm wall thickness consisting of 3 subdomains that include a die, cooling box, and take-off section was modeled in a 2D axisymmetric geometry using COMSOL Multiphysics.

The generalized heat transfer module was used to solve for the temperature distribution in the flowing melt using conductive and convective heat losses. The heat capacity of polypropylene was modeled as a function of temperature from data in Tadmor and Gogos.

The resultant temperature distribution and melt velocity were used to determine cooling rates in the mold, which were then coupled to nonisothermal crystallization data from DSC by Spruiell on polypropylene at various cooling rates.