NIPPON GOMU KYOKAISHI

Development of Crosslinked Rubber Material for High Radiation Field

Sadayoshi NAKATSUKASA, Takeshi TABASAKI, Joichi KUSANO, Fumihiro MASUK ...

2006 Volume 79 Issue 9 Pages 429-434
Published: September 15, 2006
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2324/gomu.79.429

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A new compound was developed to obtain a radiation proof crosslinked rubber which shows the excellent performance than the usual elastomer, i. e., ordinary EPDM (Ethylene-propylene-diene terpolymer) based one.
As the first study, examinations were carried out with Co-60 gamma-ray exposure test at the room temperature for various candidate rubbers.
Based on the exposure test of various rubbers, EPDM compounds were investigated in order to improve the resistance to deterioration under high radiation field. The high performance rubber was achieved by a blend of EPDM and IIR (Butyl rubber). In addition to the polymer system, antioxidant and aromatic oil were used as admixture.
The most excellent new crosslinked rubber showed no bleeding, no brooming, less change of hardness and keep 150% elongation after the gamma-ray irradiation at over 7 MGy.

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Rubber Materials for Dry Imaging Films

Yoshihisa TSUKADA, Hirohiko TSUZUKI, Yasuhiro YOSHIOKA

2006 Volume 79 Issue 9 Pages 435-439
Published: September 15, 2006
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2324/gomu.79.435

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Dry imaging film DI-HL (hereafter Film A) has been developed for a new medical imaging system that is distinguished from conventional film systems by digitization and no waste water. This film is produced with a water-based emulsion coating technology that is much eco-friendly. SBR latex is used for a binder of light-sensitive layer in Film A where images are formed of silver. This SBR latex was especially designed for Film A to give excellent image archivability in comparison with our old type SBR latex. Besides SBR latex, layer structures and image formation mechanism of Film A, and a water-based emulsion coating technology are described.

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Stabilization of Polypropylene by the Control of Primary Structure

Hisayuki NAKATANI, Minoru TERANO

2006 Volume 79 Issue 9 Pages 440-442
Published: September 15, 2006
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2324/gomu.79.440

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Thermal oxidative degradation behavior of isotactic polypropylene (iPP) with various degree of isotacticity was studied based on the activation energy (ΔE) data obtained by thermogravimetric analysis (TGA). The ΔE value displayed a negative proportion to the content of meso pentad fraction (mmmm). Since the value of mmmm was directly related to polymer chain conformation, the ΔE value was thought to have close connection with the concentration of 3₁ helix conformation in the iPP. The ΔE changes would be caused by the competition between uni- and bimolecular hydroperoxide decomposition, which was controlled by the concentration of 3₁ helix conformation. In conclusion, this result suggested that the stability of iPP could be controlled by the primary structure such as isotacticity.

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Interesting Performances of Newly Designed SIS Block Copolymers

Takeshi OHISHI, Shinya IKEDA

2006 Volume 79 Issue 9 Pages 443-447
Published: September 15, 2006
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2324/gomu.79.443

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Polystyrene-block-polyisoprene-block-polystyrene (SIS) block copolymers are used mainly in hot melt pressuresensitive adhesives (HMPSA), because their softness and elasticity can give proper tackiness and well-balanced adhesive properties. However, SISs are not used for molded elastic articles, such as elastic sheets or films, while they are quite soft and elastic.
We have developed SISs with a new design factor. Some of them show unique properties as thermoplastic elastomers.
The SISs containing “Polyisoprene Mono-block” with low molecular weight, have some interesting performances. They are sticky and very soft polymers without tackifier resins or plasticizers and show excellent tension set properties. Furthermore, they show high loss tangent in dynamic viscoelasticity test and could improve damping properties.
SIS block polymers have been also developed to show excellent transparency by reducing their impurities.
They would have some potential for elastic articles, such as elastic sheets or films.

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Polymer-Supported Chiral Catalysts for Asymmetric Reactions in Water

Shinichi ITSUNO, Yukihiro ARAKAWA, Naoki HARAGUCHI

2006 Volume 79 Issue 9 Pages 448-454
Published: September 15, 2006
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2324/gomu.79.448

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Amphiphilic polymers provide a suitable microenvironment for organic reaction in water. Organic molecules can be concentrated into the hydrophobic area in the polymer network. Hydrophilic domain in the polymer facilitated the access of the aqueous reagent or catalyst to the organic substrate in the polymer network. Organic reactions in water smoothly proceed by means of such amphiphilic polymer-supported reagents and catalysts. Such kind of approach has been attracted much attention as one of the important methodologies of the green chemistry process. Recently this approach has been applied to asymmetric reaction. Various kinds of amphiphilic polymers bearing chiral ligand have been synthesized. Chiral catalysts and reagents have been prepared with these polymeric chiral ligands. Asymmetric reactions have been nicely performed using these polymeric chiral catalysts or reagents in water.

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A Proposal Based on the Author's Experience on the Research and Development of Polymerization Catalyst: Ni-based catalyst for high cis-1, 4 polybutadiene, V-based catalyst for alternating copolymer of propylene and butadiene, and Zieglertype catalyst for polyethylene suitable for blow molding

Tsuyoshi MATSUMOTO

2006 Volume 79 Issue 9 Pages 455-459
Published: September 15, 2006
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2324/gomu.79.455

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Basic but common idea for the research and development of polymerization catalyst was proposed based on the author's experience, development of Ni-based catalyst for high cis-1, 4 polybutadiene, V-based catalyst for alternating copolymer of propylene and butadiene, and Ziegler-type catalyst for polyethylene suitable for blow molding. Though the objectives for the individual research are different, there is common way of thinking for the efficient industrial research. Firstly the researcher should have a concrete image where his (or her) objectives are accomplished. Secondary the mid point target to the project should be made. Thirdly the researchers should always think about what is the essence of the reaction.

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[title in Japanese]

[in Japanese]

2006 Volume 79 Issue 9 Pages 460-461
Published: September 15, 2006
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2324/gomu.79.460

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[title in Japanese]

[in Japanese]

2006 Volume 79 Issue 9 Pages 462-463
Published: September 15, 2006
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2324/gomu.79.462

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