ISSN:
0887-6266
Keywords:
Doi-Edwards theory
;
double-step strain flow
;
constitutive equations
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
It is widely accepted that for reversing double-step strain deformations, predictions based on the Doi-Edwards (DE) molecular theory without the independent alignment approximation (IAA) are superior to predictions obtained with the IAA, or equivalently, the Kaye-Bernstein-Kearsley-Zapas (K-BKZ) theory. This summation, however, is based on data obtained over limited ranges of strain and time: the time both between the step strains (t1) and following the second step strain (t-t1). In this study, a thorough evaluation of the DE theory is carried out using a comprehensive double-step strain flow data set. The results of this study indicate that the DE theory is an improvement over the K-BKZ theory in flows with strain reversal but only for cases when the criteria t1, t-t1 ≫ τk is satisfied. The constant τk, defined as the time beyond which the stress relaxation modulus is factorable: G(γ, t) = h(γ)G(t), is believed to represent the end of the chain retraction process in the DE theory. It appears that the dynamics of chain retraction have an important influence on double-step strain behavior and, therefore, should be accounted for in molecular-based theories devised to have general validity in this important deformation history. © 1994 John Wiley & Sons, Inc.
Additional Material:
17 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/polb.1994.090320825
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