NIPPON GOMU KYOKAISHI
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Volume 82, Issue 10
Displaying 1-9 of 9 articles from this issue
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Special Issue for General Reviews “Natural Rubber”
Introductory Remarks
General Reviews
  • [title in Japanese]
    [in Japanese], [in Japanese]
    2009 Volume 82 Issue 10 Pages 416
    Published: 2009
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2324/gomu.82.416
    JOURNAL FREE ACCESS
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  • Structure of Natural Rubber
    Seiichi KAWAHARA, Yasuyuki TANAKA
    2009 Volume 82 Issue 10 Pages 417-423
    Published: 2009
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2324/gomu.82.417
    JOURNAL FREE ACCESS
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    Natural rubber, obtained from Hevea brasiliensis, consists of ω’-terminal, two trans-1,4-isoprene units, long sequence of cis-1,4-isoprene units and α’-terminal (ω’-(trans)2-(cis)n-α’), in this order, in which the ω’ and α’ terminals represent unknown terminal groups attracted with proteins and phospholipids. The ω’ and α’ terminals are analyzed in relation to structures of polyprenols such as (CH3)2C=CHCH2-(trans)2-(cis)n-OH and (CH3)2C=CHCH2-(trans)3-(cis)n-OH. The ω’ and α’ terminals are found to play an important role in a formation of three dimensional networks of natural rubber, i.e. branching and crosslinking; the higher the molecular weight, the larger is the number of branching points. The formation of three dimensional networks is concerned with a biosynthesis of natural rubber on a surface of a rubber particle in latex stage.
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  • Biochemistry and Molecular Biology of Natural Rubber
    Satoru OKUMURA, Yasuyuki HAYASHI, Nobuko KATO
    2009 Volume 82 Issue 10 Pages 424-429
    Published: 2009
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2324/gomu.82.424
    JOURNAL FREE ACCESS
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    Natural rubber is one of the most important polymers produced by plants because it is strategic raw material used in more than 40000 products including the tire. It is focused as carbon neutral industrial material because it is synthesized from atmospheric CO2. Among over 2500 rubber producing plant species, the Para rubber tree (Hevea brasiliensis Muell. Arg.) is presently the only commercial source of natural rubber. There are some unknown points about the detail of natural rubber biosynthesis. The objective of this review is to provide readers with information on the newest trends of the natural rubber and Para rubber tree research from standpoint of biochemistry and molecular biology.
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  • Latex Allergy
    Shinichi NAKADE
    2009 Volume 82 Issue 10 Pages 430-435
    Published: 2009
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2324/gomu.82.430
    JOURNAL FREE ACCESS
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    General knowledge of latex allergy (LA) such as history, mechanism of allergy and immunity, medical treatments and regulation of safety was described.
    Among them two topics of latex allergy were introduced based on the recent results obtained in Japan.
    One is related to the reason that tree of natural rubber (NR) produces allergenic proteins. It was shown that the specific ordering unit of amino acids included in stress induced proteins (PR proteins) also exist in the proteins of NR latex.
    Other is safety map of NR products against to LA which was made based on clinical research in Japan.
    Finally, it was suggested that occurrence of new patients will be continued at low level because it is too difficult to remove high allergen products from market and LA cross to food allergy.
    And it was concluded that it was important to continue and increase the development of knowledge of LA and that it was also important to ready the alert card that serious patient could usually kept it.
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  • Processing and Compounding of Natural Rubber
    Soji KODAMA, Mitsuo AKIBA
    2009 Volume 82 Issue 10 Pages 436-442
    Published: 2009
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2324/gomu.82.436
    JOURNAL FREE ACCESS
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    This review referred to production, mastication and compounding of natural rubber. Natural rubber is made from fresh latex or spontaneous coagulum of latex. The production methods and grades of them were explained. The effects of temperature and time on mastication were discussed, and it was suggested that not only control of temperature and time but also raw rubber conditioning were important to get constant plasticity of compounded stocks. The role of inorganic fillers on physical properties of vulcanizates were emphasized.
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  • Chemical Modification of Natural Rubber
    Yoshimasa YAMAMOTO
    2009 Volume 82 Issue 10 Pages 443-449
    Published: 2009
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2324/gomu.82.443
    JOURNAL FREE ACCESS
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    The present review describes chemical modification of natural rubber, consisting of cis-1,4-polyisoprene, to introduce functional group. Natural rubber was first purified with urea in latex stage to remove proteins which inhibit precision control of the chemical modification. The resulting purified natural rubber was subjected to radical and ionic chemical reaction. Introduction of hydroxyl group, carbonyl group or functional polymer at allylic position of cis-1,4 isoprene unit was achieved with radical initiator to prepare liquid natural rubber and graft-copolymer, while it was reacted with hydrogen, peroxycarboxylic acid, carbon dioxide, water and polylactide to introduce hydrogen, epoxide, carbonate, hydroxy group and tetrahydrofuran, and ester at olefinic position, respectively.
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  • Characterization of Modified Natural Rubber through NMR Spectroscopy
    Takayuki SAITO
    2009 Volume 82 Issue 10 Pages 450-456
    Published: 2009
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2324/gomu.82.450
    JOURNAL FREE ACCESS
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    Characterization of modified natural rubber has been performed through 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. Recently, pulsed-field-gradient (PFG) technique made possible to observe a correlation between 1H and 13C in good signal to noise ratio in a short time. In fact, 2D NMR measurements with inverse pulse techniques provide a new insight into assignments of signals in NMR spectrum for epoxidized natural rubber, so that the signals are correctly assigned with various pulse sequences. Carbonated natural rubber, which is a novel functional organic material, is characterized through 2D NMR spectroscopy with various pulse techniques, in which no model compound is required for the assignments. Quantitative analysis for a reaction between epoxidized natural rubber and poly (L-lactide) is performed on the basis of the correct assignments of the signals in 1H NMR spectrum for epoxidized natural rubber. The assignments and related quantitative analysis will play an important role in a molecular design of the modified natural rubber.
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Technical Note
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