Journal of Networkpolymer,Japan
Online ISSN : 2434-2149
Print ISSN : 2433-3786
Volume 39, Issue 6
Displaying 1-5 of 5 articles from this issue
Original
  • Toshiyuki Oyama, Takumi Honda, Asuka Kawasaki, Yuichiro Tokoro
    Article type: Original
    2018 Volume 39 Issue 6 Pages 260-266
    Published: November 10, 2018
    Released on J-STAGE: March 18, 2020
    JOURNAL FREE ACCESS

    We have synthesized phenolized lignins, 2mr-L and py-L, by reacting lignin with 2-methylresorcinol (2mr) and pyrogallol (py), respectively, as the phenol analogues having multiple OH groups on an aromatic ring under acidic condition. Curing of diglycidyl ether of bisphenol A (DGEBA) by using the phenolized lignins as curing agents and 1-cyanoethyl-2- ethyl-4-methylimidazole (2E4MZ-CN) as a curing accelerator afforded BA/2mr-L and BA/py-L as the corresponding cured epoxy resins. These cured resins showed higher glass transition temperatures (Tgs) than that of the epoxy resin cured by the unmodified lignin as a curing agent (BA/L). In particular, Tg of BA/py-L was 218℃ and it was 79℃ higher than that of BA/L. The results of dynamic viscoelastic measurements of the cured resins suggested that Tgs of BA/2mr-L and BA/py-L were improved by increasing crosslink density of the cured resins, which proved the effect of introducing the phenol analogues with multiple OH groups to lignin. Thermogravimetric analysis (TGA) of BA/2mr-L and BA/py-L showed residual weights of 30% or more at 800℃ under N2 atmosphere.

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  • Ken Hirota, Masaki Omura, Kazuhiko Nakahara, Masashi Kaji
    Article type: Original
    2018 Volume 39 Issue 6 Pages 267-273
    Published: November 10, 2018
    Released on J-STAGE: March 18, 2020
    JOURNAL FREE ACCESS

    Aromatic substituted multifunctional epoxy resins were constructed, and the properties and the structure relationship were examined. As aromatic modifiers, styrene, indene and acenaphthylene were used. As a result of DMA analysis, lower modulus of elasticity was observed by introduction of aromatic substituents even though the glass transition temperature (Tg) was maintained. Moreover, flame-retardant test showed us improvement of flame-retardancy by use of aromatic substituents, indicating that the lower modulus of elasticity at high temperature related with the flammability. The type of aromatic substituents affects flow property and heat resistance, this means that the combinations of structure and modification ratio are envisaged to be more flexible molecular design.

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  • Shota Yamanaka, Masayuki Nakada, Yasushi Miyano, Takayuki Matsumoto
    Article type: Original
    2018 Volume 39 Issue 6 Pages 274-280
    Published: November 10, 2018
    Released on J-STAGE: March 18, 2020
    JOURNAL FREE ACCESS

    This paper is concerned with the effect of interlaminar toughening on the open hole tensile (OHT) static and fatigue strengths of quasi-isotropic CFRP laminates using benzoxazine resin. OHT static and fatigue tests were carried out for the interlaminar toughened (BXZ_ILT) and un-toughened (BXZ) CFRP laminates. As results, the OHT static strength for BXZ_ ILT is almost the same as that for BXZ. On the other hand, OHT fatigue strengths for BXZ_ILT are higher than those for BXZ. It can be presumed from the observation of the damages during fatigue loadings that the improvement of fatigue strength for BXZ_ILT is caused by the suppress of delamination in the side surfaces as well as the hole edge of specimen.

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Review
  • ─New Molecular Designs and Polymerization Processes of Benzoxazines─
    Takeshi Endo, Atsushi Sudo
    Article type: Review
    2018 Volume 39 Issue 6 Pages 281-289
    Published: November 10, 2018
    Released on J-STAGE: March 18, 2020
    JOURNAL FREE ACCESS

    1,3-Benzoxazines have attracted considerable attention as monomers for high performance networked polymers. Their facile syntheses with combining a wide range of phenols, amines, and formaldehyde derivatives have allowed the diverse designs of 1,3-benzoxazines. In addition, combinations of 1,3-benzoxazines with other conventional monomers and reactants have enabled the development of new polymerization processes of 1,3-benzoxazines. This review paper presents the stream of our investigations on the polymerization mechanisms of 1,3-benzoxazines that brought us to the development of 1) a series of highly reactive 1,3-benzoxazines based on neighboring group participation and introduction of thioether groups and 2) a couple of reactions of 1,3-benzoxazines such as the addition reaction with resorcinols and thiols that proceed efficiently without heating.

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  • Koji Suzumura
    Article type: Review
    2018 Volume 39 Issue 6 Pages 290-298
    Published: November 10, 2018
    Released on J-STAGE: March 18, 2020
    JOURNAL FREE ACCESS

    Automotive interior is one of the biggest market for adhesives in automobile-related business. Various type adhesives, such as emulsion type, solvent type, hot-melt type and reactive hot-melt type were used for each application depending on the required properties. In this report, I’d like to discuss about the reguired properties and development trend which are used for automotive interior, especially for door module. In addition, we also report the process-analysis method of solvent-type adhesive using Rigid-body Pendulum Type Physical Properties Testing Instrument.

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