Inverse relaxation in polypropylene

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dc.authoridDrozdov, Aleksey -- 0000-0002-6049-5813; Dusunceli, Necmi -- 0000-0002-2841-7882
dc.contributor.authorDrozdov, A. D.
dc.contributor.authorDusunceli, Necmi
dc.date.accessioned13.07.201910:50:10
dc.date.accessioned2019-07-16T09:15:54Z
dc.date.available13.07.201910:50:10
dc.date.available2019-07-16T09:15:54Z
dc.date.issued2012
dc.departmentMühendislik Fakültesi
dc.description.abstractObservations are reported on isotactic polypropylene in uniaxial tensile relaxation tests on specimens subjected to tension up to various maximum strains and retraction down to various stresses. Noticeable evolution of shapes of relaxation curves under retraction is revealed with stress at the beginning of relaxation process: with a decrease in this stress, relaxation diagrams characterized by a monotonic decay of stress with time (simple relaxation) become, first, non-monotonic (mixed relaxation), and, finally, monotonically increasing (inverse relaxation). A thorough investigation is performed on the effect of multi-cycle preloading (maximum strain per cycle, minimum stress per cycle, number of cycles, and strain rate) on transition from simple to mixed and to inverse relaxation. It is found that (1) intensity of mixed relaxation increases with maximum strain when this parameter remains below the yield strain and decreases in the post-yield region of deformations, (2) an increase in number of cycles under preloading leads to reduction of intensity of mixed relaxation and transition from mixed to inverse relaxation, (3) inverse relaxation diagrams of specimens subjected to the same preloading program with various strain rates can be superposed to construct a master-curve. A constitutive model is developed in cyclic viscoelastoplasticity of semicrystalline polymers. A polymer is thought of as two-phase continuum composed of amorphous and crystalline regions. Both phases were treated as viscoelastoplastic media whose response was governed by different kinetic equations for evolution of plastic strains and different kinematic equations for changes in relaxation rates and relaxation spectra driven by plastic flow. Good agreement is demonstrated between the experimental data in relaxation tests under retraction and the results of numerical simulation.
dc.description.sponsorshipDanish Agency for Science, Technology and Innovation [RK 2010-2012 B4]; Scientific and Technological Research Council of Turkey (TUBITAK)
dc.description.sponsorshipThe first author acknowledges financial support by the Danish Agency for Science, Technology and Innovation (project RK 2010-2012 B4). The second author acknowledges the fellowship that was supported by The Scientific and Technological Research Council of Turkey (TUBITAK).
dc.identifier.doi10.1007/s13726-012-0077-3
dc.identifier.endpage711en_US
dc.identifier.issn1026-1265
dc.identifier.issue10en_US
dc.identifier.scopusqualityQ2
dc.identifier.startpage701en_US
dc.identifier.urihttps://doi.org/10.1007/s13726-012-0077-3
dc.identifier.urihttps://hdl.handle.net/20.500.12451/4492
dc.identifier.volume21en_US
dc.identifier.wosWOS:000308649500005
dc.identifier.wosqualityN/A
dc.indekslendigikaynakWeb of Science
dc.indekslendigikaynakScopus
dc.language.isoen
dc.publisherSpringer
dc.relation.ispartofIranian Polymer Journal
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanı
dc.rightsinfo:eu-repo/semantics/embargoedAccess
dc.subjectIsotactic polypropylene
dc.subjectViscoelasticity
dc.subjectViscoplasticity
dc.subjectCyclic deformation
dc.subjectConstitutive modeling
dc.titleInverse relaxation in polypropylene
dc.typeArticle

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