A continuum model for flow-induced crystallization of polymer melts
- 1 January 1999
- journal article
- Published by Society of Rheology in Journal of Rheology
- Vol. 43 (1), 85-109
- https://doi.org/10.1122/1.550978
Abstract
A macroscopic, continuum model based on the Hamiltonian/Poisson Bracket formalism, combined with the Avrami equation, is developed to simulate flow-induced crystallization of polymer melts in homogeneous flow fields under isothermal conditions. The model predicts crystallization kinetics as well as rheological and rheooptical behavior of semicrystalline systems. The amorphous phase is modeled as a modified Giesekus fluid and the crystalline phase is approximated as a collection of multibead rigid rods that grow and orient in the flow field. The two phases are coupled with crystallinity via the dissipative Poisson brackets. The input parameters of the model can be obtained from experiments. Orders of magnitude reduction in induction times and enhancements in crystallization rates are predicted to occur under flow. Critical deformation rates are captured above which induction times sharply decrease. Calculations show increases in stiffness and strain hardening of the semicrystalline system via dramatic increases in the system stresses during crystallization. Moreover, for the temperature range studied, hydrodynamic forces dominate the undercooling effect in the regime of high deformation rates. The simulations also predict more rapid induction of crystallization following cessation of flow relative to quiescent crystallization.Keywords
This publication has 39 references indexed in Scilit:
- Transient flow-induced crystallization of a polyethylene meltJournal of Applied Polymer Science, 1997
- On‐Line determination of density and crystallinity during melt spinningPolymer Engineering & Science, 1996
- A continuum model for the dynamics of flow-induced crystallizationJournal of Polymer Science Part B: Polymer Physics, 1996
- Continuum dynamic behavior of homogeneous liquid-crystalline polymers under the imposition of shear and magnetic fieldsJournal of Rheology, 1995
- A constitutive equation for liquid‐crystalline polymer solutionsJournal of Rheology, 1993
- Finite element calculation of viscoelastic flow in a journal bearing: I. small eccentricitiesJournal of Non-Newtonian Fluid Mechanics, 1984
- An analysis of local flow effects in flow‐induced orientation and crystallizationJournal of Polymer Science: Polymer Physics Edition, 1983
- Molecular dynamics and rheological properties of concentrated solutions of rodlike polymers in isotropic and liquid crystalline phasesJournal of Polymer Science: Polymer Physics Edition, 1981
- Crystal nucleation in sheared polymer meltsPolymer Engineering & Science, 1978
- Structure development during melt spinning of linear polyethylene fibersJournal of Applied Polymer Science, 1974