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Rheological and thermomechanical properties of long-chain-branched polyethylene prepared by slurry polymerization with metallocene catalysts

Authors

  • Edward Kolodka,

    1. Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7
    Current affiliation:
    1. Department of Chemical Engineering, University of North Dakota, Grand Forks, ND 58202-8155
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  • Wen-Jun Wang,

    1. Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7
    Current affiliation:
    1. Nexwood Industries Inc, Brampton, Toronto, ON, Canada L6T 5R5
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  • Shiping Zhu,

    Corresponding author
    1. Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7
    2. Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7
    • Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7
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  • Archie Hamielec

    1. Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7
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Abstract

A series of polyethylene (PE) samples were prepared in a slurry polymerization with bis(cyclopentadienyl) zirconium dichloride (Cp2ZrCl2)/modified methylaluminoxane (MMAO) using a semibatch reactor. The samples had long-chain branch densities (LCBDs) of a 0.03–1.0 branch per 10,000 carbons and long-chain branch frequencies (LCBFs) up to a 0.22 branch per polymer molecule. The rheological and dynamic mechanical behaviors of these long-chain branched PE samples were evaluated. Increasing the LCBF significantly increased the η0's and enhanced shear thinning. Long-chain branching (LCB) also influenced the loss modulus and storage modulus. Increasing the LCBF led to enhanced G′ and G″ values at low shear rates and broader relaxation spectrums. The samples exhibited thermorheologically complex behavior. LCB also played a significant role in the dynamic mechanical behavior. Increasing the LCBF increased the stiffness of the polymer and enhanced the damping or energy dissipation. However, LCB had little influence on the crystalline structure of the PE. The α- and γ-relaxations showed little dependence on the LCBF. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 307–316, 2004

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