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Mechano-Optical Characterization of Extrusion Flow Instabilities in Styrene-Butadiene Rubbers: Investigating the Influence of Molecular Properties and Die Geometry

Georgantopoulos, Christos K.; Esfahani, Masood K.; Botha, Carlo; Naue, Ingo F. C.; Dingenouts, Nico; Causa, Andrea; Kádár, Roland; Wilhelm, Manfred

Abstract:
The extrusion flow instabilities of two commercial styrene‐butadiene rubbers are investigated as they vary in isomer content (1,4‐cis, 1,4‐trans, and 1,2 conformation) of the butadiene monomer and the molecular architecture (linear, branched). The investigated samples have similar multimodal molecular weight distribution. Two geometries of extrusion dies, slit and round capillary, are compared in terms of the type and the spatial characteristics of the flow instabilities. The latter are quantified using three methods: a highly pressure sensitive slit die, online and offline optical analysis. The highly pressure‐sensitive slit die has three piezoelectric pressure transducers (Δt ≈ 10$^{-3}$ s and Δp ≈ 10$^{-5}$ bar) placed along the die length. The characteristic frequency (f$_{Char.}$) of the flow instabilities follows a power law behavior as a function of shear rate to a 0.5 power for both materials,  𝑓$_{𝐶ℎ𝑎𝑟.}$∝𝛾$^{˙0.5}$$_{app.}$. A qualitative model is used to predict the spatial characteristic wavelength (λ) of the flow instabilities from round capillary to slit dies and vice versa. Slip velocities (V$_{s}$) are used to quantify the slippage at slit and round capillary dies as well.

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Verlagsausgabe §
DOI: 10.5445/IR/1000130812
Veröffentlicht am 23.03.2021
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Technische Chemie und Polymerchemie (ITCP)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2021
Sprache Englisch
Identifikator ISSN: 1438-7492, 0003-3146, 1439-2054, 1522-9505
KITopen-ID: 1000130812
Erschienen in Macromolecular Materials and Engineering
Verlag Wiley
Seiten Art.-Nr.: 2000801
Schlagwörter die geometry; flow instabilities; qualitative modeling; SBR; sharkskin
Nachgewiesen in Web of Science
Scopus
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