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Tensile stress measurements on linear and branches low‐density polyethylene melts. Interpretation of results with a generalized Maxwell model
Author(s) -
Muller R.,
Barea J. L.,
Sanseau P.
Publication year - 1987
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1987.070330203
Subject(s) - linear low density polyethylene , low density polyethylene , materials science , rheology , viscoelasticity , superposition principle , strain rate , polyethylene , ultimate tensile strength , composite material , branching (polymer chemistry) , simple shear , stress relaxation , shear (geology) , shear rate , thermodynamics , mechanics , creep , physics , mathematics , mathematical analysis
Dynamic shear experiments in the linear range of deformation and extensional tests at constant strain rate have been carried out on a linear low‐density polyethylene (LLDPE) melt and on two branched low‐density polyethylene (LDPE) melts with different amounts of long‐chain branching. Both the dynamic shear moduli and the tensile stress obey the time–temperature superposition principle. A simple model based on a nonaffine generalized Maxwell model with two relaxation times is proposed to describe the rheological behavior in elongation of these melts. Close agreement between the model and the experimental data can be obtained by adjusting the two relaxation times and the “slip parameter” of entanglements. The variations of these parameters with strain rate and their relationship with molecular structure are discussed.