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An irreversible thermodynamic model for semicrystalline polymers submitted to multisequence loading at large strain
Author(s) -
Mrabet Kaïs,
Rahouadj Rachid,
Cunat Christian
Publication year - 2005
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.20228
Subject(s) - thermodynamics , materials science , polyethylene , amorphous solid , polymer , high density polyethylene , relaxation (psychology) , strain rate , thermodynamic equilibrium , crystallinity , stress relaxation , statistical physics , chemistry , creep , physics , crystallography , composite material , psychology , social psychology
Some relaxation tests under uniaxial tension were performed to characterize the relaxed state of high‐density polyethylene (HDPE). These experimental results are necessary to describe and model the mechanical response in large strain by using the distribution of nonlinear relaxation (DNLR) approach developed by Cunat et al. [5–7, 10]. After recalling this thermodynamic formalism, we propose a new model to describe the relaxed state corresponding to a stationary non‐equilibrium state. This model can be obtained after two distinct internal reorganization “families” are considered. The first one is related to the relaxation mechanisms that depend on the applied strain rate (the viscous contribution of the response). The second is related to the mechanisms that are independent of the strain rate (perfect plastic contribution). In addition, the description of the equilibrium state is based on the physical contribution related to the amorphous chains' conformation changes during the applied extension (of an entropic nature). The interactions between macromolecular chains (of an energetic nature) are neglected at the equilibrium state. An example of multisequence loading simulation is discussed. POLYM. ENG. SCI. 45:42–51, 2005. © 2004 Society of Plastics Engineers