Direct observation of the deformation of isolated huge spherulites in isotactic polypropylene

In situ observation of the uniaxial deformation of isolated individual large spherulites of isotactic polypropylene was performed using films with a few large spherulites embedded in a smectic matrix. The effects of the variation of sign of birefringence in spherulites, which reflects the difference...

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Bibliographic Details
Published in:Journal of materials science 2003-12, Vol.38 (24), p.4889-4894
Main Authors: NITTA, K.-H, TAKAYANAGI, M
Format: Article
Language:English
Subjects:
Anisotropy
Applied sciences
Birefringence
Crazing
Deformation mechanisms
Equatorial regions
Exact sciences and technology
Fracture mechanics
Isotacticity
Materials science
Morphology
Organic polymers
Physicochemistry of polymers
Polar environments
Polypropylene
Properties and characterization
Spherulites
Stretching
Structure, morphology and analysis
Surface cracks
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Summary:In situ observation of the uniaxial deformation of isolated individual large spherulites of isotactic polypropylene was performed using films with a few large spherulites embedded in a smectic matrix. The effects of the variation of sign of birefringence in spherulites, which reflects the difference in lamellar morphology within spherulites were examined. In the case of a spherulite with few tangential lamellae, arcshaped cracks appear in the polar zone of the spherulite and then the radial craze-like fracture begins in the equatorial region perpendicular to the stretching axis. In the case of a spherulite with a large number of tangential lamellae, however, the radial crazing appears in the equatorial zone and then straight dark cracks, rather than arcs, running perpendicular to the stretching direction are initiated in the polar region. These results can be explained by considering the mechanical anisotropy in polypropylene lamellae.
ISSN:0022-2461
1573-4803
DOI:10.1023/b:jmsc.0000004410.56145.f1