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Showing 1–4 of 4 results
Advanced filters: Author: Naofumi Naga Clear advanced filters

  • Network structure of syndiotactic-polystyrene (sPS) or syndiotactic-poly(styrene-co-4-R-styrene) (St/RSt) -organic solvents gels has been quantitatively studied by means of a scanning microscopic light scattering (SMILS). The SMILS analysis cleared that most of the gels showed relaxation peaks derived from small mesh size ~0.6–1.8 nm and large cluster structure ~1000–6000 nm, and a gel formation model was proposed based on the analysis. Interaction between R groups (R=OH, antracenecarbonyl) affected the network structure of the gels.

    • Naofumi Naga
    • Takaaki Sakurai
    • Hidemitsu Furukawa
    Research
    Polymer Journal
    Volume: 47, P: 45-52

  • Magnetic-field-induced alignment of low-molecular-weight syndiotactic polystyrene (sPS) has achieved. Isothermal crystallization from the melting state containing local ordered domains under the 2 or 10 T of the magnetic-field-induced alignment of sPS crystals. The crystalized sPS samples formed the β phase, and the b-axis was aligned parallel to the magnetic field. Low molecular weight of sPS and high magnetic field were effective for high alignment degree. A stepwise crystallization attained higher alignment of sPS compared with an isothermal crystallization.

    • Naofumi Naga
    • Yoshie Saito
    • Masafumi Yamato
    Research
    Polymer Journal
    Volume: 48, P: 709-714

  • We describe the synthesis of a styrene–ethylene copolymer using a trivalent titanium-based polymerization catalyst system, tris(acetylacetonate)titanium/triisobutylaluminum-modified methylaluminoxane (MMAO). The catalyst system yielded a mixture of two different polymers. 13C nuclear magnetic resonance analysis of Soxhlet-extracted fractions indicated that the Soxhlet-soluble part contains the syndiotactic styrene–styrene sequence and the ethylene units adjacent to continuous styrene units. Consideration about a relation among sequence distribution, styrene content and thermal property data reasonably indicates that the block-like copolymer was produced, which contains the long syndiotactic polystyrene portions separated by the ethylene units.

    • Hideaki Hagihara
    • Chiharu Usui
    • Naofumi Naga
    Research
    Polymer Journal
    Volume: 44, P: 147-154