Mechanism for extrusion instabilities in polymer melts

M. Fyrillas, G. Georgiou, D. Vlassopoulos, S. Hatzikiriakos

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


A mechanism for explaining some of the instabilities observed during the extrusion of polymer melts is further explored. This is based on the combination of non-monotonic slip and elasticity, which permits the existence of periodic solutions in viscometric flows. The time-dependent, incompressible, one-dimensional plane Poiseuine flow of an Oldroyd-B fluid with slip along the wall is studied using a nonmonotonic slip equation relating the shear stress to the velocity at the wall. The stability of the steady-state solutions to one-dimensional perturbations at fixed volumetric flow rate is analyzed by means of a linear stability analysis and finite element calculations. Self-sustained periodic oscillations of the pressure gradient are obtained when an unstable steady-state is perturbed, in direct analogy with experimental observations.

Original languageEnglish
Pages (from-to)2498-2504
Number of pages7
JournalPolymer Engineering and Science
Issue number12
Publication statusPublished - Dec 1 1999

ASJC Scopus subject areas

  • Chemistry(all)
  • Polymers and Plastics
  • Materials Chemistry

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