A mechanism for extrusion instabilities in polymer melts

Fyrillas, M. and Georgiou, G. and Vlassopoulos, D. and Hatzikriakos, S. (1999) A mechanism for extrusion instabilities in polymer melts. Polymer Engineering and Science, 39 (12). pp. 2498-2504. ISSN 0032-3888

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Abstract:	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 Poiseuille flow of an Oldroyd-B fluid with slip along the wall is studied using a non-monotonic 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 rateis 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.
Item Type:	Article
Copyright:	© 1999 Wiley InterScience
Research Group:	Physics of Fluids (POF)
Link to this item:	http://purl.utwente.nl/publications/71511
Official URL:	http://dx.doi.org/10.1002/pen.11637
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