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α- and β-crystalline forms of isotactic polypropylene investigated by nanoindentation

✍ Scribed by Thomas Labour; Laurent Ferry; Catherine Gauthier; Philippe Hajji; Gérard Vigier

Publisher
John Wiley and Sons
Year
1999
Tongue
English
Weight
168 KB
Volume
74
Category
Article
ISSN
0021-8995

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✦ Synopsis

Under special crystallization conditions from the melt, both ␣and ␤-forms of isotactic polypropylene were produced simultaneously. The ␣and ␤-spherulites of polypropylene were differentiated under optical microscope, allowing the nanoindentation of individual spherulites of each crystallographic form. Elastic modulus and hardness of ␤-spherulites were found to be 10 and 15% respectively lower than in ␣-spherulites. The higher stiffness of ␣ may be related to the particular interlocked structure with cross-hatched lamellae, and to a lower molecular mobility in the crystallites.

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