Time-dependent rheological behavior of branched polymer melts in extensional flows
writer：Wang Wei, Hu Changxu, Li Wenwen
keywords：Numerical simulation, Complex flow, Rheological behavior, Extensional flow; Viscoelastic constitutive models; Polymer melts
source：期刊
specific source：Mechanics of Time-Dependent Materials
Issue time：2016年
The viscoelastic flow of low-density polyethylene
melts in a cross-slot channel is studied numerically for the double convected Pom–Pom (DCPP) and single modified DCPP (S–MDCPP) models. The equal low-order finite
elements for velocity–pressure–stress variables are implemented to solve the
flow fields using the pressure-stabilized iterative
fractional step algorithm. The
distributions of axial velocity along the channel centerline and the principal
stress difference achieved by numerical predictions
are in quantitative good agreement with the reported
experimental results. Furthermore, the evolution of
backbone stretch of macromolecule with flow time is demonstrated, and then we
propose an exponential decay function linking the microscale stretch relaxation
time with the macroscale flow time, in order to reveal
the stretch relaxation response of the branched polymer. The effects of
the Weissenberg number and several constitutive parameters of the S–MDCPP model
on the rheological behavior of polymer melts are discussed.
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