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Plastic deformation of low‐density polyethylene reinforced with biodegradable polylactide, Part 2: Creep characterization and modeling
Author(s) -
Rezgui F.,
G'Sell C.,
Dahoun A.,
Hiver J.M.,
Sadoun T.
Publication year - 2011
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.21796
Subject(s) - creep , materials science , viscoelasticity , low density polyethylene , composite material , strain hardening exponent , strain rate , polyethylene , deformation (meteorology) , stress (linguistics) , ultimate tensile strength , constitutive equation , yield (engineering) , characterization (materials science) , hardening (computing) , constant (computer programming) , stress relaxation , structural engineering , finite element method , nanotechnology , philosophy , linguistics , layer (electronics) , computer science , engineering , programming language
The behavior of low‐density polyethylene (LDPE) and two blends prepared with polylactide (PLA) was determined by means of a novel video‐controlled testing method under stretching at constant true strain rate, under creep at constant true stress, and under creep at constant nominal stress. Most tests were performed at 23°C and 50°C. In this second part, the experimental data are modeled with the G'Sell‐Jonas phenomenological law expressing the axial true stress versus axial true strain and axial true strain rate. This model describes correctly the various deformation stages: (i) initial viscoelasticity, (ii) plastic yielding, and (iii) strain hardening up to rupture. It shows clearly the reinforcing effect of the PLA particles that increases the yield stress in stretching experiments and slows down the deformation kinetics under creep. It is shown how the local stress/strain behavior is related to the standard force/extension curves. Consequently, it is proposed that tensile tests at constant true strain rates should be systematically preferred to creep tests for the characterization of constitutive relations because they take much less time to be performed. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.