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The Role of Allylanisole in Metallocene-Catalyzed Propylene Polymerization and Synthesis of End-Capped Oligomers

Authors

  • Muhammad Atiqullah,

    Corresponding author
    1. Center for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
    • Center for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
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  • Muhammad N. Akhtar,

    1. Center for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
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  • Michael Tinkl,

    1. Ciba, Plastic Additives Segment, Schwarzwaldallee 215 R-1059.4.02, 4002 Basel, Switzerland
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  • Neaz Ahmed

    1. Center for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
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Abstract

Propylene was copolymerized with allylanisole (AA) using Me2Si(Ind)2ZrCl2 and Et(Ind)2ZrCl2, and the methylaluminoxane MAO cocatalyst at 70 °C and a cocatalyst to catalyst (Al:Zr) molar ratio of 1 000. It was fed at 8.5 bar(g). The weight-average molecular weight, equation image, for both metallocenes decreased as the AA feed concentration increased. Therefore, allylanisole acted as an in situ chain transfer agent. The chain transfer constants, ktr/kp, of AA for Et(Ind)2ZrCl2 and Me2Si(Ind)2ZrCl2 turned out to be 0.33 and 0.40, respectively. The characterization of the resulting products by 1H NMR demonstrated that AA end-capped the isotactic poly(propylene) chains which showed to be low molecular weight oligomers; 4.96 × 103 ≤ equation image ≤ 9.80 × 103. An appropriate chain transfer mechanism for AA has been proposed.

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