Structure Formation and Crystallization Behavior of Ethylene-Isoprene Block Copolymers and Their Blends with Corresponding Homopolymers

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Author(s)

    • Gao Yuan-Ji
    • Department of Materials Science and Technology, Nagaoka University of Technology
    • Takeshita Hiroki
    • Department of Materials Science and Technology, Nagaoka University of Technology
    • Takata Yusuke
    • Department of Materials Science and Technology, Nagaoka University of Technology
    • Takenaka Katsuhiko
    • Department of Materials Science and Technology, Nagaoka University of Technology
    • Shiomi Tomoo
    • Department of Materials Science and Technology, Nagaoka University of Technology

Abstract

Time-resolved simultaneous synchrotron small-angle X-ray scattering and differential scanning calorimetry experiments have been performed on crystallization of polyethylene-polyisoprene diblock copolymers (HEI or LEI) and their blends with corresponding homopolymers, polyethylene (PE) and polyisoprene (PIp). For the neat block copolymer having a 50 wt% of the crystalline component, preexisting microphase separation structure in the melt was kept at high and low crystallization temperatures <i>T</i><sub>c</sub> (<i>T</i><sub>c</sub>≥94°C and <i>T</i><sub>c</sub><60°C), while disrupted at intermediate <i>T</i><sub>c</sub> (60°C≤<i>T</i><sub>c</sub><94°C). This complex behavior was interpreted by combination of two mechanisms. The behavior in the crystallization below 94°C was attributed to the competition between the crystallization and chain diffusion rates, that is, the fast crystallization rate at lower <i>T</i><sub>c</sub> makes it difficult to rearrange the phase structure in the melt. On the other hand, at a higher <i>T</i><sub>c</sub> (≥94°C), the preservation of the microphase separation structure was explained by a small degree of crystallinity due to the ethyl branch of polyethylene (hydrogenated poly(butadiene)). For HEI/PE blends, crystallization behavior was the simple superposition of those for HEI and PE, while, for HEI/PIp with a small composition of PE, suppression of crystallinity was observed. Crystallization kinetics in the neat block copolymer and all the blends was not so different from that in the PE homopolymer.

Journal

  • e-Journal of Soft Materials

    e-Journal of Soft Materials (4), 12-22, 2008

    THE SOCIETY OF RUBBER SCIENCE AND TECHNOLOGY, JAPAN

Codes

  • NII Article ID (NAID)
    130004941532
  • Text Lang
    ENG
  • Data Source
    J-STAGE 
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