Measurement and Modeling of Uniaxial and Planar Extensional Viscosities for Linear and Branched Polyolefin Melts in Very Fast Flows

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F70883521%3A28110%2F23%3A63568338" target="_blank" >RIV/70883521:28110/23:63568338 - isvavai.cz</a>

Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Measurement and Modeling of Uniaxial and Planar Extensional Viscosities for Linear and Branched Polyolefin Melts in Very Fast Flows

Popis výsledku v původním jazyce

In this work, novel rectangular [1-2] and circular [3-6] orifice (zero-length) dies were used to measure planar and uniaxial extensional viscosities as a function of strain, strain rate and temperature for polypropylene and polyethylene melts using Cogswell [2, 6-7] and Gibson [8-9] methodologies. The obtained experimental data were combined with shear and uniaxial extensional viscosity data determined at very high strain rates. The ability of a molecularized Generalized Newtonian Fluid (mGNF) [M. Zatloukal and J. Drabek, “Generalized Newtonian fluid constitutive equation for polymer liquids considering chain stretch and monomeric friction reduction for very fast flows modeling,” Physics of Fluids 33(8), 083106 (2021)], Giesekus [10] and explicit Yao [11-12] constitutive equations to describe the measured data was tested. For the first time, the monomeric friction coefficient for fully aligned chains was determined for linear and branched polypropylenes using a high-strain-rate limiting value of uniaxial extensional viscosity. It has been shown that including the effect of the chemical environment (i.e., the role of the oligomeric solvent) using a simplified version of the mGNF constitutive equation (instead of the commonly used Newton’s law) can significantly improve the ability of the Giesekus and Yao viscoelastic constitutive equations to describe the measured experimental data, especially at very high strain rates using adjustable parameters with a clear physical meaning. Since the friction coefficient of polyolefin melts controls the flow-induced crystallization and extensional rheology at high extensional rates, the obtained results are considered valuable not only with respect to the fundamental understanding of polymer physics and the development/validation of advanced constitutive equations, but also with regard to understanding the stability of non-Newtonian flows in advanced polymer processing, such as optimized production of polymer membranes for energy storage membranes via cast film process or filtration membranes prepared by the meltblown process used for example in the production of face masks.

Název v anglickém jazyce

Measurement and Modeling of Uniaxial and Planar Extensional Viscosities for Linear and Branched Polyolefin Melts in Very Fast Flows

Popis výsledku anglicky

In this work, novel rectangular [1-2] and circular [3-6] orifice (zero-length) dies were used to measure planar and uniaxial extensional viscosities as a function of strain, strain rate and temperature for polypropylene and polyethylene melts using Cogswell [2, 6-7] and Gibson [8-9] methodologies. The obtained experimental data were combined with shear and uniaxial extensional viscosity data determined at very high strain rates. The ability of a molecularized Generalized Newtonian Fluid (mGNF) [M. Zatloukal and J. Drabek, “Generalized Newtonian fluid constitutive equation for polymer liquids considering chain stretch and monomeric friction reduction for very fast flows modeling,” Physics of Fluids 33(8), 083106 (2021)], Giesekus [10] and explicit Yao [11-12] constitutive equations to describe the measured data was tested. For the first time, the monomeric friction coefficient for fully aligned chains was determined for linear and branched polypropylenes using a high-strain-rate limiting value of uniaxial extensional viscosity. It has been shown that including the effect of the chemical environment (i.e., the role of the oligomeric solvent) using a simplified version of the mGNF constitutive equation (instead of the commonly used Newton’s law) can significantly improve the ability of the Giesekus and Yao viscoelastic constitutive equations to describe the measured experimental data, especially at very high strain rates using adjustable parameters with a clear physical meaning. Since the friction coefficient of polyolefin melts controls the flow-induced crystallization and extensional rheology at high extensional rates, the obtained results are considered valuable not only with respect to the fundamental understanding of polymer physics and the development/validation of advanced constitutive equations, but also with regard to understanding the stability of non-Newtonian flows in advanced polymer processing, such as optimized production of polymer membranes for energy storage membranes via cast film process or filtration membranes prepared by the meltblown process used for example in the production of face masks.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

10404 - Polymer science

Projekt

<a href="/cs/project/GA21-09174S" target="_blank" >GA21-09174S: Viskoelastické neizotermální modelování procesu vytlačování polymerních fólií pro výrobu membrán zahrnující tokem indukovnou krystalizaci</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů