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Effect of network relaxation on void propagation and failure in isotactic polypropylene at large strain

Authors

  • Bing Na,

    Corresponding author
    1. Department of Materials Science and Engineering, East China Institute of Technology, Fuzhou 344000, People's Republic of China
    • Department of Materials Science and Engineering, East China Institute of Technology, Fuzhou 344000, People's Republic of China
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  • Ruihua Lv,

    1. Department of Materials Science and Engineering, East China Institute of Technology, Fuzhou 344000, People's Republic of China
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  • Wenfei Xu

    1. Department of Materials Science and Engineering, East China Institute of Technology, Fuzhou 344000, People's Republic of China
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Abstract

The important role of network relaxation in the voiding and fracture toughness of isotactic polypropylene (iPP) has been explored with video-aid tensile tests, two-dimensional small-angle X-ray scattering (2D-SAXS) measurements, and morphological observations. The results indicated that macroscopic volume dilatation related to voiding became lower during large deformation of iPP sample with rich γ phase (denoted as γ-iPP) cooled at 1°C/min, compared with one with exclusive α form (referred to α-iPP) quenched in air. Furthermore, void propagation perpendicular to the tensile direction, demonstrated by Guinier approximation analysis of 2D-SAXS results, was suppressed to a large extent in such a γ-iPP sample. Less network relaxation, resulted from its peculiar crystalline and amorphous phases, was responsible for lower volume dilatation and slower void propagation in the γ-iPP sample. Meanwhile, less network relaxation and suppressed transverse void propagation contributed to higher toughness in the γ-iPP sample. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

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