Analysis of the flow instabilities in the extrusion of polymeric melts
type: Item
instance of: scholarly article
zbMATH Open document ID: 0870.76001
author: A. C. T. Aarts
publication date: 1997-02-26T00:00:00Z
Mathematics Subject Classification ID: 76-02
Mathematics Subject Classification ID: 76E99
Mathematics Subject Classification ID: 82D60
zbMATH DE Number: 982107
zbMATH Keywords: Johnson-Segalman-Oldroyd fluid
zbMATH Keywords: Kaye-Berstein-Kearsley-Zapas fluid
zbMATH Keywords: sharkskin-type of instability
zbMATH Keywords: spurt flows
zbMATH Keywords: cylindrical capillary
zbMATH Keywords: constant pressure gradient
zbMATH Keywords: constant volumetric flow rate
zbMATH Keywords: persistent oscillations
MaRDI profile type: Publication
title: Analysis of the flow instabilities in the extrusion of polymeric melts
review text: In this book, written as the author's Ph.D. thesis, mathematical analyses and numerical computations have been used to investigate various types of instabilities during an extrusion process of polymeric melts. Particular attention is paid to the sharkskin-type of instability as well as to the spurt flows connected with persistent oscillations in the spin line. The following flows are discussed in greater detail:NEWLINENEWLINENEWLINE1) Pressure-driven shear flow of a Kaye-Berstein-Kearsley-Zapas (KBKZ) fluid, modelling the flow of a polymer melt through a cylindrical capillary under a constant pressure gradient. In particular, the mathematical formulation, the steady-state solutions, the stability analysis and the transient flow behaviour are considered. It is shown that the spurt phenomenon can be explained on the basis of constitutive instabilities, and the wall-slip boundary condition is not necessary.NEWLINENEWLINENEWLINE2) Piston-driven shear flow of Johnson-Segalman-Oldroyd (JSO) model, describing the flow of a polymeric melt through a cylindrical capillary with a constant volumetric flow rate. It is shown that persistent oscillations may occur as observed in experiments, and the corresponding critical conditions for the onset of oscillations are established.NEWLINENEWLINENEWLINE3) Extrusion of a JSO fluid, combined with compression, leading to a global relation between the pressure in the barrel and the volumetric flow rate in the capillary. The occurrence of persistent oscillations has been explained by means of linearized stability analysis.NEWLINENEWLINENEWLINEIn the last section an agreement of theoretical results with experimental observations is presented, and further perspectives connected with various forms of instabilities are discussed in detail.NEWLINENEWLINENEWLINEIn the paper, very spectacular from the mathematical point of view, certain physical assumptions may be questioned. These are isothermal and inertialess conditions of flow which may serio…
reviewed by: S. Zahorski
description: scientific article; zbMATH DE number 982107