Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

Sagir Adamu, Muhammad Atiqullah, Zuhair O. Malaibari, Mamdouh A. Al-Harthi, Abdul-Hamid M. Emwas, Anwar Ul-Hamid

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    3 Scopus citations

    Abstract

    This study reports a novel conceptual framework that can be easily experimented to evaluate the effects of hydrodynamic boundary layer mass transfer, methylaluminoxane (MAO) anion design, and comonomer steric hindrance on metallocene-catalyzed ethylene polymerization. This approach was illustrated by conducting homo- and isomeric copolymerization of ethylene with 1-hexene and 4-methyl-1-pentene in the presence of bis(n-butylcyclopentadienyl) zirconium dichloride (nBuCp)2ZrCl2, using (i) MAO anion 1 (unsupported [MAOCl2]−) and pseudo-homogeneous reference polymerization, and (ii) MAO anion 2 (supported Si−O−[MAOCl2]−) and in-situ heterogeneous polymerization. The measured polymer morphology, catalyst productivity, molecular weight distribution, and inter-chain composition distribution were related to the locus of polymerization, comonomer effect, in-situ chain transfer process, and micromixing effect, respectively. The peak melting and crystallization temperatures and %crystallinity were mathematically correlated to the parameters of microstructural composition distributions, melt fractionation temperatures, and average lamellar thickness. These relations showed to be insightful. The comonomer-induced enchainment defects and the eventual partial disruption of the crystal lattice were successfully modeled using Flory and Gibbs–Thompson equations. The present methodology can also be applied to study ethylene−α-olefin copolymerization, performed using MAO-activated non-metallocene precatalysts.
    Original languageEnglish (US)
    Pages (from-to)92-105
    Number of pages14
    JournalJournal of the Taiwan Institute of Chemical Engineers
    Volume60
    DOIs
    StatePublished - Nov 28 2015

    ASJC Scopus subject areas

    • Chemical Engineering(all)
    • Chemistry(all)

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