ASYMMETRIC MARKOVIAN PROCESS IN THE POLYPROPYLENE OBTAINED BY ZIEGLER-NATTA CATALYST WITH EXTERNAL ALKOXYSILANE DONORS

Riichiro Chujo, Eiji Sakaguchi, Mika Härkönen, Jukka V. Seppälä

    Research output: Contribution to journalArticleScientificpeer-review

    Abstract

    The formulae for conditional probabilities are derived with the terms of NMR triad tacticities for the polymers whose polymerization process is described by the asymmetric Markovian process. The obtained formulae are applied to the polypropylenes polymerized by Ziegler-Natta catalysts with external alkoxysilane donors. For both of unfractionated samples and heptane-insoluble fractions, the followings were clarified: 1) on the transformation from symmtric to (fluctuating) asymmetric centers the transformation of one (hereafter, L) site is much enhanced than that of D site, 2) the monotonous increase of isotacticity as a result of the increase of the concentration of the donors is due to the increase of p(LL), 3) aromatic donors are effective than aliphatic ones for the improvement of isotacticity, and 4) the improvement of isotacticity after an addition of the alkoxysilanes is not due to the contribution from both of L and D sites, but the positive contribution from the former is larger than the negative one from the latter.

    Original languageUndefined/Unknown
    Pages (from-to)647-651
    Number of pages5
    JournalKOBUNSHI RONBUNSHU
    Volume51
    Issue number10
    Publication statusPublished - 1994
    MoE publication typeA1 Journal article-refereed

    Keywords

    • POLYPROPYLENE
    • ASYMMETRIC MARKOVIAN
    • EXTERNAL ALKOXYSILANE DONOR
    • TRIAD TACTICITY
    • FLUCTUATING SITE
    • POLYMERIZATION
    • MODELS

    Cite this