Polimerek kristályosodása és olvadása, XXVI. Az izotaktikus polipropilén β-módosulatának magas homérsékletu, hedrites kristályosodása

Translated title of the contribution: Crystallization and melting of polymers, XXVI. High-temperature hedritic crystallization of the β-modification of isotactic polypropylene

J. Varga, Gottfried W. Ehrenstein

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The high-temperature crystallization of the β-modification of polypropylene (β-IPP) induced by an active β-nucleating agent was studied by polarizing light microscopy. It was established that, in the early stage of crystallization of β-IPP, hedrites were formed as precursors of the spherulitic crystallization. Hedrites seen flat-on were characteristic hexagonal formations (hexagonites) with low birefringence. The central core of hexagonites had positive birefringence. Hedrites seen edge-on were rod-like formations with strong negative birefringence which would transform into a radially symmetric spherulitic form through sheaf-like then oval (ovalite) arrangements. Hedrites may reach considerable sizes (several hundred micrometers). At temperatures of isothermal crystallization higher than the critical (T(βα) = 140 -C), hedrites with mixed polymorphic structures of α- and β-modifications were formed.

Original languageHungarian
Pages (from-to)352-358
Number of pages7
JournalMagyar Kemiai Folyoirat, Kemiai Kozlemenyek
Volume103
Issue number8
Publication statusPublished - Aug 1997

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Polypropylenes
Crystallization
Polymers
Melting
Birefringence
Temperature
Optical microscopy

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

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title = "Polimerek krist{\'a}lyosod{\'a}sa {\'e}s olvad{\'a}sa, XXVI. Az izotaktikus polipropil{\'e}n β-m{\'o}dosulat{\'a}nak magas hom{\'e}rs{\'e}kletu, hedrites krist{\'a}lyosod{\'a}sa",
abstract = "The high-temperature crystallization of the β-modification of polypropylene (β-IPP) induced by an active β-nucleating agent was studied by polarizing light microscopy. It was established that, in the early stage of crystallization of β-IPP, hedrites were formed as precursors of the spherulitic crystallization. Hedrites seen flat-on were characteristic hexagonal formations (hexagonites) with low birefringence. The central core of hexagonites had positive birefringence. Hedrites seen edge-on were rod-like formations with strong negative birefringence which would transform into a radially symmetric spherulitic form through sheaf-like then oval (ovalite) arrangements. Hedrites may reach considerable sizes (several hundred micrometers). At temperatures of isothermal crystallization higher than the critical (T(βα) = 140 -C), hedrites with mixed polymorphic structures of α- and β-modifications were formed.",
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