Modeling the spatial characteristics of extrusion flow instabilities for styrene-butadiene rubbers: Investigating the influence of molecular weight distribution, molecular architecture, and temperature
Journal article, 2021

The extrusion flow instabilities of three commercial styrene-butadiene rubbers (SBR) are investigated as a function of molecular weight distribution (MWD); molecular architecture (linear, branched); and temperature. The samples have multimodal MWD, with the main component being SBR and a low amount, less than 10 wt. %, of low-molecular weight hydrocarbons. Deviation from the Cox-Merz rule at high angular frequencies/shear rates becomes intense as the amount of medium-molecular weight component increases. Optical analysis is used to identify and quantify spatial surface distortions, specifically wavelength (λ) and height (h), of the different types of extrusion flow instabilities. Qualitative constitutive models are reviewed and used to fit the experimental data for the spatial characteristics of extrusion flow instability. The fitting parameters as obtained by the models are correlated with molecular properties of the materials. It is found that the characteristic spatial wavelength (λ) increases as the extrusion temperature decreases. Hence, the influence of temperature on the spatial characteristic wavelength is investigated and an Arrhenius behavior is observed.


Christos K. Georgantopoulos

Karlsruhe Institute of Technology (KIT)

Masood K. Esfahani

Karlsruhe Institute of Technology (KIT)

Carlo Botha

Karlsruhe Institute of Technology (KIT)

Michael A. Pollard

Karlsruhe Institute of Technology (KIT)

Ingo F. C. Naue

Karlsruhe Institute of Technology (KIT)

Andrea Causa

Pirelli & C. S.p.A.

Roland Kádár

Chalmers, Industrial and Materials Science, Engineering Materials

Manfred Wilhelm

Karlsruhe Institute of Technology (KIT)

Physics of Fluids

0031-9171 (ISSN)

Vol. 33 9 093108

Subject Categories

Textile, Rubber and Polymeric Materials

Fluid Mechanics and Acoustics

Condensed Matter Physics



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