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Morphology and stress whitening in polypropylene at various strain rates

Farahani, M. F ; Sharif University of Technology | 2023

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  1. Type of Document: Article
  2. DOI: 10.1007/s00289-022-04504-8
  3. Publisher: Springer Science and Business Media Deutschland GmbH , 2023
  4. Abstract:
  5. Polypropylene (PP) and its composites have an increasing use in automobile and domestic industries. Since the results published regarding effect of strain rate on yield behavior are not compatible, and there is a high attention paid to the effect of strain rate on deformation behavior, the understanding of structure–property relation in PP is crucial. In this research, the effect of strain rate on deformation mechanism of PP and its relation with stress whitening have been studied. Microscopic observations and tensile tests in different strain rates on neat PP samples have suggested that crazing is the prominent deformation mechanism in entire range of the examined strain rates (0.001–0.033 s−1). Microscopic results showed that there is a transition strain rate (εT∘) at which both craze extension and stress whitening reach their maximum value. As the number and extension of craze increased, scattering entities in the specimen increased, the specimen became increasingly white and, consequently, there was an increase in whitening intensity up to about 0.03 s−1. By further enhancing the strain rate beyond 0.03 s−1, craze extension decreased and stress whitening became smaller due to the thermal softening mechanism activated in the adiabatic deformation. Craze initiation, craze propagation, combination of crazes, and in turn craze-crack transition were the common phenomena with increase in the strain rate. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature
  6. Keywords:
  7. Deformation behavior ; Polypropylene ; Strain rate ; Stress whitening ; Thermal softening
  8. Source: Polymer Bulletin ; Volume 80, Issue 9 , 2023 , Pages 9465-9477 ; 01700839 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s00289-022-04504-8