Journal of Networkpolymer,Japan
Online ISSN : 2434-2149
Print ISSN : 2433-3786
Volume 42 , Issue 4
Showing 1-5 articles out of 5 articles from the selected issue
Original
  • Kazuki Ofusa, Naoki Hashimoto
    Type: Original
    2021 Volume 42 Issue 4 Pages 128-138
    Published: July 10, 2021
    Released: December 04, 2021
    JOURNAL RESTRICTED ACCESS

    New acrylates synthesized from plant-derived raw materials such as glycerin and sorbitol were evaluated as UVcurable resins. Glycerin triacrylate (GTA) has the features of low viscosity, high hardness and high adhesion as compared with conventional trifunctional or higher functional acrylates. Glycerin carbonate acrylate (GCA), which is an acrylate of glycerin carbonate synthesized from glycerin and carbonic acid ester, has the features of high UV curability, high Tg and low water absorption rate as compared with conventional monofunctional acrylates. Ethoxylated sorbitol acrylate has the features of high water solubility, UV curability, high hardness, and water dilution as compared with conventional hydrophilic acrylates. The biomass degree of GTA and GCA are as high as 35% and 50%, respectively. They are expected to be applied to inks, paints, adhesives, etc. as photo-curing resins with low environmental load.

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  • Koki Yamamoto, Yoshihito Suzuki, Akikazu Matsumoto
    Type: Original
    2021 Volume 42 Issue 4 Pages 139-150
    Published: July 10, 2021
    Released: December 04, 2021
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    Organic-inorganic hybrid materials were prepared using a thiol-ene reaction between random-type silsesquioxanes containing a mercapto group and N-allylmaleimide copolymers. First, various copolymers of N-allylmaleimide with different sequence structures and allyl contents were synthesized by ternary radical copolymerization of N-allylmaleimide combined with N-(2-ethylhexyl)maleimide and diisobutene, and binary copolymerization with 2-ethylhexyl acrylate in chloroform at 60℃. Next, the copolymers were thermally cured using thiol-modified silsesquioxanes as the cross-linking agent in the presence of triallyl isocyanurate, and the reactions of the allyl and mercapto groups were monitored by IR spectroscopy. All of the obtained organic-inorganic hybrid polymer materials showed excellent heat resistance and transparency. The effects of the ratio of allyl groups to mercapto groups in feed composition of the thermosetting systems and the content of the allyl groups in the copolymers on the thermal and mechanical properties of the cured products were investigated.

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  • Gel Formation in Tris(hydroxymethyl)aminomethane Buffer Solution and its Use as Composite Material with Monomeric Dopamine
    Yuya Itono, Kozo Matsumoto
    Type: Original
    2021 Volume 42 Issue 4 Pages 151-157
    Published: July 10, 2021
    Released: December 04, 2021
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    Dopamine-modified carboxymethyl cellulose (DOPA-CMC)s with various degrees of DOPA substitution (DS)(7~9%) were synthesized, and their solution behaviors and adhesion properties toward pig skin were investigated under various conditions. DOPA-CMC (DS9%) in phosphate buffer solutions (PBS, pH6.0, pH7.0, pH8.0) was a colorless liquid, while its solution in tris(hydroxymethyl)animomethane buffer solution (Tris buffer solution, pH8.0) changed to a brown gel.The polymer solution was cast on a pig skin strip to obtain the polymer film. The test piece was prepared by crimping the polymer film to another pig skin strip and by drying for 24 h. Then the tensile shear strength of the sample was measured; this value was evaluated as dry adhesion strength. An analogously prepared sample was further immersed in water for 1 h and the tensile shear strength was measured; this value was evaluated as wet adhesion strength. The dry adhesion strengths of the test piece prepared from the PBS (pH6.0-8.0) solutions were high and almost constant at 0.71 MPa-0.53 MPa, while the wet adhesion strengths remained low at 0.04 MPa-0.07 MPa. The dry adhesion strength of the test piece prepared from the Tris(pH8.0) buffer solution was 0.63 MPa, but its wet adhesion strength rose to 0.16MPa, which was significantly higher than those of the PBS solutions. This high wet adhesion strength of the Tris buffer solution was supposed to be caused by the crosslink of the DOPA-CMC due to the oxidative coupling of the DOPA groups. We also found that composite materials prepared by mixing DOPA-CMC (DS7%) and DOPA in the Tris buffer solution showed higher wet adhesion strength than that without DOPA.

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  • Masashi Kaji, Tomomi Kai, Koichiro Ogami
    Type: Original
    2021 Volume 42 Issue 4 Pages 158-164
    Published: July 10, 2021
    Released: December 04, 2021
    JOURNAL RESTRICTED ACCESS

    There is an epoxy resin having an ether ether ketone (EEK) structure as one measure for improving the heat resistance of epoxy resin. After obtaining a phenolic oligomer (HREEK) by the reaction of resorcinol and 4,4'-difluorobenzophenone, an epoxidation reaction was performed to synthesize an epoxy resin (GREEK) having a softening point of 62-94℃. As a result of evaluating the physical properties of the cured product using phenol novolac as a curing agent, the glass transition temperature was 146℃, which was 19℃ higher than that of the bisphenol A type epoxy resin (DGBPA). In addition, low thermal expansion and high thermal decomposition stability were confirmed due to the EEK structure. Furthermore, when HREEK was used as a curing agent, the 10 wt% weight loss temperature was 421℃ and the residual carbon rate was 53.7wt%, which were extremely high values as a cured epoxy resin product

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Review
  • Kenji Mimura
    Type: Review
    2021 Volume 42 Issue 4 Pages 165-171
    Published: July 10, 2021
    Released: December 04, 2021
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    In recent years, heat dissipation and high heat resistance properties are required to the insulating material due to the high performance and downsizing of power module products. In this paper, the research contents of the resin composite material filled with the high thermal conductivity filler in the cyanate ester resin were introduced. Cyanate ester resin is an excellent insulating material with good formability due to low viscosity and very high heat resistance. The thermal conductivity of resin composite materials was dramatically improved by orientation control of boron nitride (BN) particles using agglomerated BN consisting of flake-like BN particles. The resin composite material with excellent heat resistance and heat dissipation has been developed by blending agglomerated BN into the cyanate ester resin.

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