Characterization methods for strain-induced damage in polypropylene

Johannes Wiener, Florian Preissegger, Bernhard Plank, Florian Arbeiter, Otmar Kolednik, Gerald Pinter

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Various methods are used to characterize the deterioration of mechanical properties in polymers. The focus is set on distinguishing between time-dependent and irreversible damage in two different grades of polypropylene. First, digital image correlation is utilized to capture the stress–strain behavior during monotonic tensile tests. Changes in specimen volume are recorded throughout the experiment and serve as an indicator for crazes and voids. However, the elastic modulus, E, cannot be monitored throughout the entire experiment. Further analysis is performed in the form of cyclic load–unload tests. E and the residual strain, εres, as a function of the applied strain, εappl, are obtained for each cycle. Results show that E primarily suffers from the time-dependent behavior of the tested polymers in this case. Subsequently, an alternative technique is applied, where specimens are prestrained and then allowed to relax. In the following dynamic mechanical analysis, viscoelastic effects can be avoided. Considerations on the onset and evolution of damage are made. Ultimately, these results are confirmed through microcomputed tomography, where the shapes and densities of defects are captured in high resolution.

Original languageEnglish
Pages (from-to)1959-1973
Number of pages15
JournalPolymer Engineering and Science
Volume62
Issue number6
DOIs
Publication statusPublished - Jun 2022

Keywords

  • computed tomography
  • damage
  • elastic modulus decay
  • polypropylene

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