Chain regularity of isotactic polypropylene determined by different thermal fractionation methods

Zsuzsanna Horváth, Alfréd Menyhárd, Petar Doshev, Markus Gahleitner, József Varga, Cornelia Tranninger, Béla Pukánszky

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The chain regularity of isotactic polypropylene (iPP) homopolymer and random copolymers was characterized by different thermal fractionation methods in this study. Different stepwise temperature programs were applied in a calorimeter (DSC), in order to develop a method which is significantly faster than stepwise isothermal segregation technique (SIST) and provides reliable information about the chain regularity of iPP. Our studies prove that self-seeding accelerates the crystallization process during annealing in SSA-DSC experiments (successive self-nucleation and annealing). Consequently, the time of isothermal steps can be shortened significantly in the SSA-DSC method. On the other hand, we found that step time should not be too short if the goal of the measurement is the determination of average chain regularity. Our results clearly indicate that both the experimental conditions and the evaluation technique influence the obtained results. A standard experimental procedure is proposed for reliably determining the average chain regularity of iPP. The length of the SSA-DSC temperature program developed in this study is much shorter compared to that of the conventional SIST measurements used recently for such experiments. The proposed SSA-DSC program makes the reliable characterization of a large number of samples on an acceptable timescale possible.

Original languageEnglish
Pages (from-to)235-245
Number of pages11
JournalJournal of Thermal Analysis and Calorimetry
Volume118
Issue number1
DOIs
Publication statusPublished - Sep 17 2014

Keywords

  • Chain regularity
  • Isotactic polypropylene
  • Molecular structure
  • SIST
  • Stepwise crystallization
  • Successive self-nucleation and annealing (SSA-DSC)

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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