Influence of thermal treatments, molecular weight, and molecular weight distribution on the crystallization of b-isotactic polypropylene

Six samples of isotactic polypropylene were examined to study the influence of the thermal treatments and the molecular weights and their distribution on the *b-crystallization of the polymer. The highest amount of the *b-phase was obtained by isothermal crystallization and in correspondence of high...

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Bibliographic Details
Published in:Journal of applied polymer science 2004-01, Vol.91 (2), p.1008-1012
Main Authors: Marigo, A, Marega, C, Causin, V, Ferrari, P
Format: Article
Language:English
Online Access:Get full text
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Summary:Six samples of isotactic polypropylene were examined to study the influence of the thermal treatments and the molecular weights and their distribution on the *b-crystallization of the polymer. The highest amount of the *b-phase was obtained by isothermal crystallization and in correspondence of high average molecular weights and wide molecular weight distributions. Small-angle X-ray scattering pointed out that a partial *b-crystallization seems not to influence the lamellar morphology parameters. Differential scanning calorimetry measurements, at different heating rates, allowed us to confirm that the multiple melting endotherms behavior of the *b-phase is to be correlated to a melting-recrystallization-melting mechanism.
ISSN:0021-8995