Effect of high-temperature annealing on the elastoplastic response of isotactic polypropylene in loading-unloading tests

A. D. Drozdov, J. De C. Christiansen

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

A series of uniaxial tensile loading-unloading tests is performed on isotactic polypropylene at room temperature. Prior to mechanical testing, injection-molded specimens are annealed for 24 h at temperatures T = 145, 150, 155, 158, 160, 163, and 165°C, which cover the entire region of high-temperature annealing temperatures. A constitutive model is developed for the elastoplastic behavior of a semicrystalline polymer at small strains. The stress-strain relations are determined by six adjustable parameters that are found by matching observations in cyclic tests. Fair agreement is demonstrated between the experimental data and the results of numerical simulation. It is shown that all material constants are affected by the annealing temperature, which is explained by changes in the crystalline morphology driven by thermal treatment. Some of the adjustable parameters experience finite jumps in the vicinity of the critical temperature Tc = 159°C. These jumps are attributed to the α2 → α2′ phase transformation.

Original languageEnglish
Pages (from-to)186-196
Number of pages11
JournalJournal of Applied Polymer Science
Volume90
Issue number1
DOIs
StatePublished - 3 Oct 2003
Externally publishedYes

Keywords

  • Annealing
  • Poly(propylene)
  • Structure-property relations
  • Tensions

ASJC Scopus subject areas

  • Chemistry (all)
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Materials Chemistry

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