Validity of separable BKZ model for large amplitude oscillatory shear
作者:
A. J. Giacomin,
R. S. Jeyaseelan,
T. Samurkas,
J. M. Dealy,
期刊:
Journal of Rheology
(AIP Available online 1993)
卷期:
Volume 37,
issue 5
页码: 811-826
ISSN:0148-6055
年代: 1993
DOI:10.1122/1.550396
出版商: The Society of Rheology
关键词: Polyethylene;Viscoelasticity;Oscillatory shear, large amplitude;Melts, nonlinear rheology of;Wagner equation, of polymer rheology;SHEAR FLOW;OSCILLATIONS;VISCOELASTICITY;MELTS;POLYMERS;STRESS−STRAIN RELATION;DAMPING;RELAXATION
数据来源: AIP
摘要:
Large amplitude oscillatory shear (LAOS) is a useful tool for the study of nonlinear viscoelasticity in polymeric liquids. To concisely describe the response of a material to such a test, it is desirable to make use of a constitutive equation. In this way, the response can be described in terms of the parameters of the rheological model. We have found a separable BKZ model, e.g., Wagner’s equation, to be useful in this regard for LDPE IUPAC X. The damping function determined in step shear experiments does not lead to accurate predictions of the LAOS response. For a given low frequency, however, it is possible to fit the parameters of a simple damping function equation to the LAOS response at one strain amplitude and to use these parameter values to reliably predict the response at other strain amplitudes. Thus, the Wagner equation provides a basis for the concise description of the response of LDPE IUPAC X to large amplitude oscillatory shear experiments at low frequencies. Conversely, it was found that the response of a HDPE melt to large amplitude oscillatory shear cannot be concisely described by the Wagner equation.
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