Time-dependent response of polypropylene after strain reversal

A. D. Drozdov

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Observations are reported in tensile relaxation tests on specimens subjected to stretching up to various maximum strains max followed by retraction to various minimum strains . Experimental data show that shapes of relaxation curves on pre-loaded samples are strongly affected by strain increment Δ = max - : (i) when Δ is small, stress monotonically decays with time, (ii) with an increase in Δ, the relaxation process becomes non-monotonic, and (iii) at relatively large increments Δ, stress grows with time. A two-phase constitutive model is derived for the viscoelastic and viscoplastic responses of semicrystalline polymers under arbitrary deformations with small strains. Adjustable parameters in the stress-strain relations are found by fitting the observations. Numerical simulation demonstrates that the model correctly describes the time-dependent behavior of polypropylene subjected to cyclic pre-loading in creep and relaxation tests.

Original languageEnglish
Pages (from-to)3221-3233
Number of pages13
JournalInternational Journal of Solids and Structures
Issue number24
StatePublished - 1 Dec 2010
Externally publishedYes


  • Constitutive model
  • Cyclic deformation
  • Isotactic polypropylene
  • Viscoelasticity
  • Viscoplasticity

ASJC Scopus subject areas

  • Modeling and Simulation
  • Materials Science (all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Applied Mathematics


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