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Predecessor
Volume 77, Issue 9
Displaying 1-7 of 7 articles from this issue
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Yoshiharu MITSUHASHI, Jun HATAKEYAMA, Yoshito OHTAKE, Mutsuhisa FURUKA ...2004 Volume 77 Issue 9 Pages 301-305
Published: 2004
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSIn order to elucidate the degradation behavior of NBR caused by residual chlorine in tap water, NBR diaphragms used in chlorine-contained tap water for about 4 and 9 years at an ambient temperature in Yokohama City and the unused product were analyzed by means of FT-IR, EPMA and XPS. NBR usually leads to hardening and degradation with increase of crosslinking density by heat or UV. However, NBR used in tap water softened and chlorine atom invaded into surface layer of NBR diaphragm. The degradation process of the NBR in the tap water is considered as follows: (1) the α-H of the butadiene double-bond of the NBR is susceptible to substitution by chlorine; (2) the chlorinated NBR reacted with other NBR and subtraction of the α-H produced the radical; (3) the radical subsequently produced hydroperoxide at the α-position and an aldehyde was formed by decomposition similar to that in the oxidation degradation mechanism of polybutadiene; (4) vulcanized points were cleaved simultaneously. These processes are expected to lower the molecular weight of the NBR and lead to softening and degradation.View full abstractDownload PDF (1061K) -
Hiroshi Iizuka, Yoshihiro Yamashita2004 Volume 77 Issue 9 Pages 306-311
Published: 2004
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSThe stress-strain behavior of rubber is non-linear and is usually described using the strain energy density function. From the viewpoint of the input data for finite element analysis (FEA), a number of models have been proposed to describe the behavior. Therefore, it is necessary to understand the feature of the models. Namely, the selection of the models is still a difficult subject when the FEA is performed. In this paper, the authors review the optimum identification of the stress-strain data of rubber for FEA input. This technical note is the summary of the discussion in the sectional meeting"mechanical properties of rubber"in the society of rubber industry, Japan. Ogden and Mooney-Rivlin models guarantee a marvelous expression under sufficient testing data, although they do not give a good description under insufficient testing data. Neo-Hookean model has possibilities to give an acceptable identification result under insufficient testing data, such as only a simple tensile testing data.View full abstractDownload PDF (904K) -
1. The Synthesis of Olefin ElastomersShojiro KAITA, Yasuo WAKATSUKI2004 Volume 77 Issue 9 Pages 312-316
Published: 2004
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSDesign and fine-tuning of olefin-polymerization systems with organometallic catalysts have attracted recent interest. These catalysts, unlike the classical Ziegler-Natta systems, generate"single"active sites that enable more precise control of molecular weight, molecular weight distribution, and in particular, stereo-regularity of the resulting polymer. Such systems, initially devoted to polymerization of ethylene and propylene targeting engineering plastics, are recently being applied to the synthesis of novel elastomers. This article is a brief introduction of such topics, including synthesis of EPM-equivalent polymers by homo-polymerization of propylene, and isotactic-atactic or isotactic-hemi-isotactic stereo-block polymerization of propylene. Strategies aiming at these new elastomers based on tailor-made organometallic catalysts are also described.View full abstractDownload PDF (939K) -
Part5. New Understanding of the Unsolved Phenomena in the Carbon ReinforcementYoshihide FUKAHORI2004 Volume 77 Issue 9 Pages 317-323
Published: 2004
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSIn part 4, the author proposed a new concept with a new interface model for the carbon black reinforcement of rubbers. Here, the discussion is focused on how we should understand the typical phenomena, essential but unsolved so far in the reinforcement of rubbers with carbon blacks.
The formation of the super network structure consisting of the linkage of dispersed carbon blacks with strands of oriented molecules in SH layer generates the quite high stress under large extension and the corresponding high tensile strength of the body. Great hysteresis energy given in rubbers highly filled with fine carbon blacks under large extension is composed of the apparent hysteresis energy (about 40%) due to the uckling of the extended strands and viscoelastic energy (about 60%). Energetic behavior of the carbon black-filled rubbers results from the energetic characteristics of SH layer, the easier molecular sliding generating the lower stress at higher temperature.View full abstractDownload PDF (1495K) -
6. Investigation of Mechanical Properties of PSAs by Using Retardation SpectrumYoshiaki URAHAMA2004 Volume 77 Issue 9 Pages 324-329
Published: 2004
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSA pressure sensitive adhesive is a lightly cross-linked polymer with the capability of 1, 000-2, 000% of large deformation. The behavior completely differs from the behavior of linear viscoelasticity. Numerical differentiation of the large-deformation creep data was carried out, and the retardation spectrum was obtained.
As a result, the followings became clear.
(1) It became clear that the influence of the cross-linking degree of PSA appears in a long-term region, while the effect of chemical composition of a PSA appears in a short-term region.
(2) In polymer/tackifier PSA system, it became clear that the short-term region of the retardation spectrum shape depends on the chemical structure of the tackifier, while the long-term region of it depends on the softening point.View full abstractDownload PDF (1022K) -
[in Japanese]2004 Volume 77 Issue 9 Pages 330-331
Published: 2004
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSDownload PDF (946K) -
[in Japanese]2004 Volume 77 Issue 9 Pages 332-333
Published: 2004
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSDownload PDF (591K)
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