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Modeling of nonlinear extensional and shear rheology of low‐viscosity polymer melts
Author(s) -
Poh Leslie,
Li Benke,
Yu Wei,
Narimissa Esmaeil,
Wagner Manfred H.
Publication year - 2021
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.25637
Subject(s) - extensional viscosity , rheometer , materials science , rheology , viscoelasticity , stress relaxation , thermodynamics , viscosity , polymer , shear (geology) , rheometry , constitutive equation , shear flow , composite material , shear viscosity , creep , physics , finite element method
The hierarchical multi‐mode molecular stress function (HMMSF) model developed by Narimissa and Wagner [Rheol. Acta 54, 779–791 (2015), and J. Rheol. 60, 625–636 (2016)] for linear and long‐chain branched (LCB) polymer melts were used to analyze the set of transient elongational and shear viscosity data of two LCB low‐density polyethylenes (1840H and 2426 k), and a linear poly‐(ethylene‐co‐α‐butene), PEB A‐780090 as reported by [Li et al. J. Rheol. 64, 177 (2020)], who had developed a new horizontal extensional rheometer to extend the lower limits of elongational viscosity measurements of polymer melts. Comparison between model predictions and elongational stress growth data reveals excellent agreement within the experimental window, and good consistency with shear stress growth data, based exclusively on the linear‐viscoelastic relaxation spectrum and only two nonlinear model parameters, the dilution modulus G D for extensional flows, and in addition a constraint release parameter for shear flow.