Structural determination of ethylene-propylene-diene rubber (EPDM) containing high degree of controlled long-chain branching

Authors

  • Susanta Mitra,

    Corresponding author
    1. The Danish Polymer Centre, Risø National Laboratory, Frederiksborgvej 399, Roskilde DK-4000, Denmark
    • The Danish Polymer Centre, Risø National Laboratory, Frederiksborgvej 399, Roskilde DK-4000, Denmark
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  • Mikkel Jørgensen,

    1. The Danish Polymer Centre, Risø National Laboratory, Frederiksborgvej 399, Roskilde DK-4000, Denmark
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  • Walther Batsberg Pedersen,

    1. The Danish Polymer Centre, Risø National Laboratory, Frederiksborgvej 399, Roskilde DK-4000, Denmark
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  • Kristoffer Almdal,

    1. The Danish Polymer Centre, Risø National Laboratory, Frederiksborgvej 399, Roskilde DK-4000, Denmark
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  • Debasish Banerjee

    1. Department of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110
    Current affiliation:
    1. GE Global Research, SABIC Innovative Plastics Program, John F Welch Technology Centre (GE India Technology Centre Pvt. Ltd.), 122, EPIP, Phase 2, Hoodi Village, Whitefield Road, Bangalore 560066, India
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Abstract

This work highlights an attempt to characterize the degree and nature of long-chain branching (LCB) in an unknown sample of ethylene-propylene-diene rubber (EPDM). Two EPDM rubbers selected for this study were comparable in comonomer compositions but significantly different with respect to molar mass and the presence of LCB. Both rubbers contained 5-ethylidene-2-norbornene (ENB) as diene. Solution cast films of pure EPDM samples were used for different characterization techniques. 1H-NMR, and 13C-NMR were used for assessing the comonomer ratios and LCB. Size exclusion chromatography (SEC) equipped with triple detector system was used to determine the molar mass (both absolute and relative) and polydispersity index (PDI). Presence of branching was also detected using sec-viscometry. Rheological analysis has also been used for characterizing LCB. Finally, on the basis of the experimental findings and the available theories, an attempt was made to identify the chemical nature and degree of LCB. This study reveals the possibility of detailed characterization of molecular architecture of EPDM containing LCB by comparing with an essentially linear EPDM in light of an existing theory. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

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