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Effect of network relaxation on void propagation and failure in isotactic polypropylene at large strain
Author(s) -
Na Bing,
Lv Ruihua,
Xu Wenfei
Publication year - 2009
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.30532
Subject(s) - materials science , tacticity , void (composites) , composite material , small angle x ray scattering , ultimate tensile strength , toughness , perpendicular , amorphous solid , scattering , relaxation (psychology) , crystallography , polymer , optics , geometry , polymerization , psychology , social psychology , chemistry , physics , mathematics
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