Effect of die exit stress state, Deborah number, uniaxial and planar extensional rheology on the neck-in phenomenon in polymeric flat film production

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F70883521%3A28110%2F18%3A63520670" target="_blank" >RIV/70883521:28110/18:63520670 - 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

Effect of die exit stress state, Deborah number, uniaxial and planar extensional rheology on the neck-in phenomenon in polymeric flat film production

Popis výsledku v původním jazyce

In this work, effect of the second to first normal stress difference ratio at the die exit, -N2/N1, uniaxial extensional strain hardening, ηE,U,max/(3×η0), planar-to-uniaxial extensional viscosity ratio, ηE,P/ηE,U, and Deborah number, De, has been investigated via viscoelastic isothermal modeling utilizing 1D membrane model and a single-mode modified Leonov model as the constitutive equation. Based on the performed parametric study, it was found that there exists a threshold value for De and ηE,U,max/(3×η0), above which, the neck-in starts to be strongly dependent on -N2/N1. It was found that such critical De decreases if -N2/N1, ηE,U,max/(3×η0) increases and/or ηE,P/ηE,U decreases. Numerical solutions of the utilized model were successfully approximated by a dimensionless analytical equation relating the normalized maximum attainable neck-in with ηE,U,max/(3×η0), ηE,P/ηE,U, -N2/N1 and De. Suggested equation was tested by using literature experimental data. It was found that approximate model predictions are in a very good agreement with the corresponding experimental data for low as well as very high Deborah numbers, at which neck-in strongly depends on -N2/N1. It is believed that the obtained knowledge together with the suggested simple model can be used for optimization of the extrusion die design (influencing flow history and thus die exit stress state), molecular architecture of polymer melts and processing conditions to suppress neck-in phenomenon in production of very thin polymeric flat films.

Název v anglickém jazyce

Effect of die exit stress state, Deborah number, uniaxial and planar extensional rheology on the neck-in phenomenon in polymeric flat film production

Popis výsledku anglicky

In this work, effect of the second to first normal stress difference ratio at the die exit, -N2/N1, uniaxial extensional strain hardening, ηE,U,max/(3×η0), planar-to-uniaxial extensional viscosity ratio, ηE,P/ηE,U, and Deborah number, De, has been investigated via viscoelastic isothermal modeling utilizing 1D membrane model and a single-mode modified Leonov model as the constitutive equation. Based on the performed parametric study, it was found that there exists a threshold value for De and ηE,U,max/(3×η0), above which, the neck-in starts to be strongly dependent on -N2/N1. It was found that such critical De decreases if -N2/N1, ηE,U,max/(3×η0) increases and/or ηE,P/ηE,U decreases. Numerical solutions of the utilized model were successfully approximated by a dimensionless analytical equation relating the normalized maximum attainable neck-in with ηE,U,max/(3×η0), ηE,P/ηE,U, -N2/N1 and De. Suggested equation was tested by using literature experimental data. It was found that approximate model predictions are in a very good agreement with the corresponding experimental data for low as well as very high Deborah numbers, at which neck-in strongly depends on -N2/N1. It is believed that the obtained knowledge together with the suggested simple model can be used for optimization of the extrusion die design (influencing flow history and thus die exit stress state), molecular architecture of polymer melts and processing conditions to suppress neck-in phenomenon in production of very thin polymeric flat films.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

10404 - Polymer science

Projekt

<a href="/cs/project/GA16-05886S" target="_blank" >GA16-05886S: Výzkum vlivu smykové a tahové reologie polymerních tavenin na stabilitu produkce meltblown nanovláken a fólií</a><br>

Návaznosti

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

Rok uplatnění

2018

Kód důvěrnosti údajů

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