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Evaluate the nonlinear viscoelasticity of polyolefin melts using the Larson model
Author(s) -
Lin GwoGeng,
Song YiHu,
Shiu TaiYi
Publication year - 2014
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.23788
Subject(s) - rheology , materials science , viscoelasticity , high density polyethylene , polyolefin , nonlinear system , stress relaxation , polypropylene , relaxation (psychology) , viscosity , rheometry , composite material , shear rate , thermodynamics , elongation , stress (linguistics) , polyethylene , mechanics , creep , physics , psychology , social psychology , linguistics , philosophy , layer (electronics) , quantum mechanics , ultimate tensile strength
Nonlinear rheological properties of polyolefins have long been studied and predicted by using the Larson model with the damping function generally obtained from the stress relaxation measurements. In this study, we investigate the nonlinear rheological properties of high density polyethylene (HDPE) and polypropylene (PP) using the Larson model with damping functions obtained from either the dynamic frequency sweep or the stress relaxation test. Experimental measurements and their corresponding model predictions for the rheological parameters were then compared to evaluate the applicability of the Larson model to the nonlinear rheology, and the following conclusions could be achieved. The steady shear viscosity could be satisfactorily described by the Larson model with the damping functions obtained from the two different methods, except at shear rates higher than 10 3 s −1 . The predicted first normal stresses also account for the measured data, except for those using the stress relaxation data showing a little deviation for the PP sample. In addition, the predictions for elongation viscosity are also in good agreement with the experimental results within the short range of elongation rate achieved in this work. POLYM. ENG. SCI., 54:2354–2361, 2014. © 2013 Society of Plastics Engineers