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Structural time dependency in the rheological behavior of molten polymers
Author(s) -
Dealy J. M.,
Tsang Wm. K.;W.
Publication year - 1981
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.1981.070260409
Subject(s) - rheology , rheometer , materials science , shear rate , shear (geology) , polymer , composite material , shear flow , constitutive equation , thermodynamics , finite element method , physics
In order to elucidate the role of reentanglement processes in the rheology of molten polymers, we have used the interrupted shear test and the reduction‐;in‐;shear‐;rate test to study a linear and a branched polyethylene at 170°C. A cone‐;plate rheometer was used, and shear rates were thus limited to values below 1 sec −1 . For both polymers, the characteristic time for reentanglement was found to be significantly greater than the time scales associated with the relaxation of shear and normal stresses after cessation of steady shear. This observation has important implications for the modelling of melt flow in plastics processes and the evaluation of constitutive equations.