Three-site mechanism and molecular weight: Time dependency in liquid propylene batch polymerization using a MgCl2-supported Ziegler-Natta catalyst

Fumihiko Shimizu, J.T.M. Pater, G. Weickert

    Research output: Contribution to journalArticleAcademic

    12 Citations (Scopus)

    Abstract

    This article demonstrates that the molecular weight of propylene homopolymer decreases with time, and that the molecular weight distribution (MWD) narrows when a highly active MgCl2-supported catalyst is used in a liquid pool polymerization at constant H2 concentration and temperature. To track the change in molecular weight and its distribution during polymerization, small portions of homo polymer samples were taken during the reaction. These samples were analyzed by Cross Fractionation Chromatograph (CFC), and the resulting data were treated with a three-site model. These analyses clearly showed that the high molecular weight fraction of the distribution decreases as a function of time. At the same time, the MWD narrows because the weight-average molecular weight decreases faster than the number-average molecular weight. A probable mechanism based on the reaction of an external donor with AlEt3 is proposed to explain these phenomena.
    Original languageUndefined
    Pages (from-to)1035-1047
    JournalJournal of applied polymer science
    Volume81
    Issue number4
    DOIs
    Publication statusPublished - 2001

    Keywords

    • MgCl2-supported Ziegler-Natta catalyst
    • IR-59718
    • liquid pool propylene polymerization
    • three-site model
    • time dependency
    • Molecular weight

    Cite this

    @article{159c40321bd5481989f9e422b4b2851f,
    title = "Three-site mechanism and molecular weight: Time dependency in liquid propylene batch polymerization using a MgCl2-supported Ziegler-Natta catalyst",
    abstract = "This article demonstrates that the molecular weight of propylene homopolymer decreases with time, and that the molecular weight distribution (MWD) narrows when a highly active MgCl2-supported catalyst is used in a liquid pool polymerization at constant H2 concentration and temperature. To track the change in molecular weight and its distribution during polymerization, small portions of homo polymer samples were taken during the reaction. These samples were analyzed by Cross Fractionation Chromatograph (CFC), and the resulting data were treated with a three-site model. These analyses clearly showed that the high molecular weight fraction of the distribution decreases as a function of time. At the same time, the MWD narrows because the weight-average molecular weight decreases faster than the number-average molecular weight. A probable mechanism based on the reaction of an external donor with AlEt3 is proposed to explain these phenomena.",
    keywords = "MgCl2-supported Ziegler-Natta catalyst, IR-59718, liquid pool propylene polymerization, three-site model, time dependency, Molecular weight",
    author = "Fumihiko Shimizu and J.T.M. Pater and G. Weickert",
    year = "2001",
    doi = "10.1002/app.1525",
    language = "Undefined",
    volume = "81",
    pages = "1035--1047",
    journal = "Journal of applied polymer science",
    issn = "0021-8995",
    publisher = "Wiley",
    number = "4",

    }

    Three-site mechanism and molecular weight: Time dependency in liquid propylene batch polymerization using a MgCl2-supported Ziegler-Natta catalyst. / Shimizu, Fumihiko; Pater, J.T.M.; Weickert, G.

    In: Journal of applied polymer science, Vol. 81, No. 4, 2001, p. 1035-1047.

    Research output: Contribution to journalArticleAcademic

    TY - JOUR

    T1 - Three-site mechanism and molecular weight: Time dependency in liquid propylene batch polymerization using a MgCl2-supported Ziegler-Natta catalyst

    AU - Shimizu, Fumihiko

    AU - Pater, J.T.M.

    AU - Weickert, G.

    PY - 2001

    Y1 - 2001

    N2 - This article demonstrates that the molecular weight of propylene homopolymer decreases with time, and that the molecular weight distribution (MWD) narrows when a highly active MgCl2-supported catalyst is used in a liquid pool polymerization at constant H2 concentration and temperature. To track the change in molecular weight and its distribution during polymerization, small portions of homo polymer samples were taken during the reaction. These samples were analyzed by Cross Fractionation Chromatograph (CFC), and the resulting data were treated with a three-site model. These analyses clearly showed that the high molecular weight fraction of the distribution decreases as a function of time. At the same time, the MWD narrows because the weight-average molecular weight decreases faster than the number-average molecular weight. A probable mechanism based on the reaction of an external donor with AlEt3 is proposed to explain these phenomena.

    AB - This article demonstrates that the molecular weight of propylene homopolymer decreases with time, and that the molecular weight distribution (MWD) narrows when a highly active MgCl2-supported catalyst is used in a liquid pool polymerization at constant H2 concentration and temperature. To track the change in molecular weight and its distribution during polymerization, small portions of homo polymer samples were taken during the reaction. These samples were analyzed by Cross Fractionation Chromatograph (CFC), and the resulting data were treated with a three-site model. These analyses clearly showed that the high molecular weight fraction of the distribution decreases as a function of time. At the same time, the MWD narrows because the weight-average molecular weight decreases faster than the number-average molecular weight. A probable mechanism based on the reaction of an external donor with AlEt3 is proposed to explain these phenomena.

    KW - MgCl2-supported Ziegler-Natta catalyst

    KW - IR-59718

    KW - liquid pool propylene polymerization

    KW - three-site model

    KW - time dependency

    KW - Molecular weight

    U2 - 10.1002/app.1525

    DO - 10.1002/app.1525

    M3 - Article

    VL - 81

    SP - 1035

    EP - 1047

    JO - Journal of applied polymer science

    JF - Journal of applied polymer science

    SN - 0021-8995

    IS - 4

    ER -