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Volume 78, Issue 3
Displaying 1-7 of 7 articles from this issue
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Mayumi HAYASHI, Katsunari INAGAKI, Akio IMAI, Akira HIRAO2005 Volume 78 Issue 3 Pages 91-97
Published: 2005
Released on J-STAGE: May 19, 2008
JOURNAL FREE ACCESSMuch attention has been paid to the end-functionalized solution styrene-butadiene rubber (S-SBR) for the purpose of improving the interaction between the polymer and silica filler. Recently, we have been developing a new one-step methodology based on living anionic polymerization and 1, 1-diphenylethylene chemistry for synthesizing well-defined functionalized SBR with dimethylamino groups at both chain ends. This one-step methodology involves living anionic copolymerization of styrene and butadiene by treating with functionalized initiator synthesized from two equivalent of dimethylamino-functionalized DPE with sec-BuLi. The resulting copolymers were characterized by GPC, SLS, NMR, titration, and polymer reactions to show the expected chain-end-functionalized structures. As an extention of this methodology, a more complex multi-functionalized SBR with three dimethylamino groups at both chain ends and in chain could be successfully synthesized by treating with functionalized initiator synthesized from three equivalent of the DPE with sec-BuLi.View full abstractDownload PDF (1004K) -
Yoshiharu MITSUHASHI, Jun HATAKEYAMA, Yoshito OHTAKE, Mutsuhisa FURUKA ...2005 Volume 78 Issue 3 Pages 98-102
Published: 2005
Released on J-STAGE: May 19, 2008
JOURNAL FREE ACCESSIn order to elucidate the degradation behavior of NBR caused by high concentration chlorine water, NBR samples corroded in 200ppm chlorine water and in pure water were analyzed by means of EPMA, FT-IR and XPS. The degradation process of the NBR corroded in high concentration chlorine water is considered as follows: (1) an α-H of the butadiene double bond in NBR molecule is subject to substitution by chlorine; (2) the chlorinated NBR abstracts an α-H in another NBR molecule to cause the elimination of HCl, which generates polymer radicals; (3) the polymer radicals thus produced add to polybutadiene double-bonds in the other NBR. It is concluded that residual chlorine reacts with NBR by chlorination and oxidation mechanisms and that these reactions lead to hardening and degradation of NBR through the increase in the crosslinking density.View full abstractDownload PDF (1096K) -
Yasuhiro SHIBATA, Hiroaki KOUZAI2005 Volume 78 Issue 3 Pages 103-105
Published: 2005
Released on J-STAGE: May 19, 2008
JOURNAL FREE ACCESSIt was confirmed that photodegradation of diene polymers in solutions is accelerated by the addition of carbazole as a sensitizer. The viscosities of the polymer solutions in chloroform were markedly lowered with UV-irradiation when carbazole was added to the solution. The decrease in the solution viscosities, along with FT-IR and 1H NMR spectra of the irradiated polymers, indicates that the degradation of the diene polymers proceeds through the autooxidation mechanism. It was inferred that the acceleration effect of carbazole on the diene polymer degradation was caused by carbazyl radical cation generated by the dissociation of CT complex between carbazole and solvent.View full abstractDownload PDF (457K) -
Keisuke CHINO2005 Volume 78 Issue 3 Pages 106-110
Published: 2005
Released on J-STAGE: May 19, 2008
JOURNAL FREE ACCESSThermoreversible Hydrogen-bond crosslinking isoprene rubber (THC-IR) was synthesized by modification of isoprene rubber (IR) with maleic anhydride followed by the addition of 3-amino-1, 2, 4-triazole(ATA), in solid phase. The mechanical properties of the resulting rubber were more similar to the sulfur-vulcanized rubber than general thermoplastic elastomers (ex. SEBS). Although the tensile strength and elongation at break were lower than those of a corresponding sulfur-cured rubber, the moduli were as high as those of sulfur-cured rubber. Reforming could be repeated more than 10 times without significantly changing its mechanical properties. Differential scanning calorimetry (DSC) revealed that the superior mechanical properties and good recyclability are attributable to the strong hydrogen bonding. The TRC-IR showed an endothermic transition peak at around 185°C on the DSC chart, indicating cleavage of the hydrogen bonding. Moreover, small angle X-ray scattering (SAXS) clarified the crosslinking point is aggregated structure of ca. 5nm by supramolecular hydrogen bonding. A hypothetical model was suggested which comprises strong crosslinking moiety formed by the seven points hydrogen bonds. The thermoreversible crosslinking system could be applied to EPM and AEM, as well. These rubbers also showed superior mechanical properties as well as excellent recyclability.View full abstractDownload PDF (915K) -
Kinro HASHIMOTO, Mitsuru MATSUZAWA, Nobuyuki HARASAWA, Yuji WATANABE2005 Volume 78 Issue 3 Pages 111-118
Published: 2005
Released on J-STAGE: May 19, 2008
JOURNAL FREE ACCESSDME (dimethylether) has currently been used for aerosol and is expected to be provided as a fuel in and after 2006 when many projects related with DME starts. Since DME contains oxygen atom in its molecules and does not contains any sulfur compounds, it may have superiorities as a soot-free fuel. From the economical point of view, it will be reasonable to use infrastructure for liquefied petroleum gas (LPG), because the physical properties of DME are close to those of LPG. On the other hand, it is necessary to check the suitability of common rubber and plastic used as sealing materials, since the chemical structure and properties of LPG and DME are different. From various types of screening test, it has come to clear that PTFE, compressed sheet gaskets and FFKM are promising against both LPG and DME. IIR, HNBR, NBR, and other elastic materials are, however, necessary to be evaluated in both LPG and DME before use.View full abstractDownload PDF (1510K) -
[in Japanese], [in Japanese]2005 Volume 78 Issue 3 Pages 119-121
Published: 2005
Released on J-STAGE: May 19, 2008
JOURNAL FREE ACCESS -
Part 1. Polymer-Polymer Miscibility and Applications of Miscible BlendsTakashi INOUE2005 Volume 78 Issue 3 Pages 122-127
Published: 2005
Released on J-STAGE: May 19, 2008
JOURNAL FREE ACCESSThermodynamic discussion on the miscibility between dissimilar polymers leads to: (i) the contribution of combinatorial entropy of mixing to the miscibility is negligibly small and (ii) the miscibility is mostly caused by the hydrogen bonding-type intermolecular specific interactions and the repulsive intramolecular interactions in random copolymers. By analyzing the fee energy curve, the free energy of mixing as a function of composition, phase diagrams are described in terms of the binodal curve and the spinodal curve. Criterions of polymer-polymer miscibility are deduced in the framework of such thermodynamic discussion.
The polymer-polymer miscibility is applied: (i) to improve melt-processability (PPE/PS), (ii) to improve ozone resistance (NBR/PVC), (iii) to reduce optical anisotropy (to provide zero-birefringence plastics), (iv) to improve heat resistance (PEEK/PET), and (v) to make materials flexible (PVC/EVA).View full abstractDownload PDF (1053K)
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