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

Result code in 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>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

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

Original language description

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.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

10404 - Polymer science

Project

<a href="/en/project/GA16-05886S" target="_blank" >GA16-05886S: Investigation the effect of polymer melt shear and elongational rheology on production stability of meltblown nanofibers and films</a><br>

Continuities

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

Publication year

2018

Confidentiality

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