NIPPON GOMU KYOKAISHI
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Volume 84, Issue 6
Displaying 1-5 of 5 articles from this issue
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Regular Papers
  • Novel Viscoelasticity Measurement Method Based on AFM Force Mapping and JKR Analysis
    So FUJINAMI, Ken NAKAJIMA, Toshio NISHI
    2011 Volume 84 Issue 6 Pages 171-175
    Published: 2011
    Released on J-STAGE: December 29, 2011
    DOIhttps://doi.org/10.2324/gomu.84.171
    JOURNAL FREE ACCESS
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    The Johnson-Kendall-Roberts (JKR) elastic contact model has been mostly applied for the analyses of force-distance curve measurements. We employed an AFM force mapping measurement on natural rubber (NR)/butyl rubber (IIR) vulcanized blend. The force-distance curve fitted well to the JKR model on elastic NR and rigid zinc oxide region but did not on viscoelastic IIR region. We calculated the deviated areas surrounded by a JKR curve and a experimental plot and mapped them to two-dimensional image. The derived image emerged viscoelastic IIR region from other rigid or rubbery region. This deviation will be due to viscoelastic properties of the materials; the glass transition temperature of IIR is close to the measurement condition. While whole energy dissipation of a cycle of each force-distance curve is strongly affected by adhesive hysteresis, the method we proposed here is free from adhesion because it calculates a difference from the JKR theory, in which adhesion is taken into consideration.
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  • Dissolution Behavior of the Antioxidant in PP in Tap Water and Evaluation of the Polymer Degradation
    Mio GONOKAMI, Yoshito OHTAKE, Seiichi KAWAHARA
    2011 Volume 84 Issue 6 Pages 176-181
    Published: 2011
    Released on J-STAGE: December 29, 2011
    DOIhttps://doi.org/10.2324/gomu.84.176
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    Use of polypropylene products in tap water decreases its lifetime as compared to in the air. The reason is that antioxidants, which determine polymers' lifetime, dissolve into water rapidly and polypropylene products become easy to deteriorate. Especially, when water contains residual chlorine, polypropylene products generate carbonyl group which shows the oxidation degradation on its surface and this leads to the strength degradation.
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  • Swelling of Vulcanized Rubber by Ethanol Blended Gasoline
    Takehito MORI, Takeshi KONDO, Yoshito OHTAKE
    2011 Volume 84 Issue 6 Pages 182-188
    Published: 2011
    Released on J-STAGE: December 29, 2011
    DOIhttps://doi.org/10.2324/gomu.84.182
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    The swelling behavior of vulcanized acrylonitrile-butadiene rubber (NBR) having different nitrile content, styrene-butadiene rubber (SBR) and fluorine rubber (FKM) were examined in ethanol blended gasoline. For NBRs, the swelling rate of extra and medium high nitrile NBR is highest in the gasoline containing 25 vo1% ethanol (E25). In the gasoline containing less than 50 vol% ethanol, extra high CN NBR showed higher resistance to the solvent than the other whereas no such clear difference was observed in the gasoline containing 85 or more vol% of ethanol (E85). For SBR, the swelling rate is highest in gasoline without ethanol (E0) and decreased with the content of ethanol. FKM showed almost no swelling in the mixture with wide range of ethanol content.
    Although the ethanol-blended gasoline can be considered as a mixture of aliphatic and aromatic hydrocarbon and polar ethanol, aromatic hydrocarbon was selectively absorbed in NBR and SBR. This can be explained using the Hansen solubility parameter.
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General Reviews
  • Remarkable Progress in Self-reinforcement of Elastomers Generated Through Strain-induced Crystallization (Part 1);
    “Macroscopic Inhomogeneity in Cross-linked Rubbers Proved by the Newest Observation”
    Yoshihide FUKAHORI
    2011 Volume 84 Issue 6 Pages 189-196
    Published: 2011
    Released on J-STAGE: December 29, 2011
    DOIhttps://doi.org/10.2324/gomu.84.189
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    The newest observation disclosed the clear image of macroscopic inhomogeneous structures of cross-linked rubbers. Cross-linking agent, sulfur disperses as a bulky ZnS in rubber matrix quite inhomogeneously, which generates the heterogeneous phase separation of cross-linked (about 30%) and uncross-linked (about 70%) phases during vulcanization. The mechanically fundamental units of the cross-linked and the uncross-linked phase are 1~2 μm and a few hundred nm, respectively. The soft uncross-linked phase surrounding the hard cross-linked phase mainly extends in external extension and swelling, thus the system deforms ununiformly, i.e. non-affinly. The above observation seems to support the models proposed by the author.
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Technical Note
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