Journal of The Adhesion Society of Japan
Online ISSN : 2187-4816
Print ISSN : 0916-4812
ISSN-L : 0916-4812
Volume 48, Issue 7
Displaying 1-4 of 4 articles from this issue
Review
Technical Report
  • Hiroaki CHO, Yasunori ASHIDA, Shuhei NAKAMURA, Wataru SHIMIZU, Yasushi ...
    2012 Volume 48 Issue 7 Pages 237-247
    Published: July 01, 2012
    Released on J-STAGE: June 30, 2014
    JOURNAL FREE ACCESS
    In this paper, a durability of a new room temperature vulcanizing (RTV) silicone under high temperature and high humidity is presented in addition to the mechanical and adhesive properties. Because the authors have succeeded in making a new hardener for RTV silicones as a replacement of organic tin compounds in compliance with the EU regulation. It is presented that how the new RTV silicone is better durability and mechanical properties, than those made with conventional hardener. The new hardener (NHD) consists of a titanium alkoxide and a carboxylate ester as a hardener and a promoter in quimolar, respectively. It has been found that the silicone made with the NHD stands comparison with that made with organic tin compound hardener on mechanical properties and shows better mechanical properties than that made with titanium chelate compound or tetraethoxytitanium. A silicone composite made with a combination filler of a reinforcing fumed silica treated by dimethylsilane at surface and an extending agent of the ground calcium carbonate yields a good endurance for heat and humidity and a good adhesive strength.
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Original Paper
  • Hiroko NAKANO, Yasuhisa SEKIGUCHI, Toshiyuki SAWA
    2012 Volume 48 Issue 7 Pages 229-236
    Published: July 01, 2012
    Released on J-STAGE: June 30, 2014
    JOURNAL FREE ACCESS
    The stress distributions at the interfaces in the scarf adhesive joints under static bending moments were analyzed using two-dimensional and three-dimensional finite element calculations. The effects of the scarf angle, adhesive Young's modulus and the adhesive thickness on the interface stress distributions were examined. It was found that the singular stress at the edges of the interfaces decreased as the adhesive Young's modulus increased and the adhesive thickness decreased. The singular stress at the edge of the interfaces obtained from the 3-D was found to be larger than that from the 2-D FEM. The bending moment when the joint was ruptured was also predicted using elasto-plastic FEM calculations. For verification of the FEM calculation results, the strains on the adherends and the bending moment when the joint was ruptured were measured. The measured results of the strains and the bending moment when the joint was ruptured were fairly consistent with the results obtained from the 3-D FEM calculations.
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Original Paper
  • Masaaki YAMADA, Hayato KATO, Kinji TAKI
    2012 Volume 48 Issue 7 Pages 222-228
    Published: July 01, 2012
    Released on J-STAGE: June 30, 2014
    JOURNAL FREE ACCESS
    To develop novel adhesives that can bond wood species with poor bonding capacity to each other, five kinds of polyvinylalcohol (PVA) samples with different degrees of saponification were prepared. The storage stability of the aqueous solutions, dispersibility of the oily components, and adhesion performance of the wood were examined. The following conclusions were drawn. Because perfectly saponified PVA contains many hydrophilic groups and has a tendency to crystallize, the viscosity of an aqueous solution increases quickly, and the solution readily turns into a gel. Thus, the storage stability is poor. By blending PVA that is rich in hydrophobic groups with the perfectly saponified PVA, the increase in viscosity was suppressed. An increasing number of hydrophobic groups in the PVA sample corresponded to improved dispersibility of 4,4'-diphenylmethane diisocyanate (pMDI) and oily components of Chamaecyparis in the aqueous solutions. A comparison between two polymer systems containing similar amounts of hydrophobic groups showed that the dispersibility of oily components in aqueous solutions of the blended system was better than that in solutions of the non-blended system. The adhesion performance of wood specimens coated with essential oils of Chamaecyparis was examined using these adhesives. There was no significant difference between the adhesion performance of the blended system and that of the non-blended system when pMDI was not added to the adhesive. When pMDI was added to the adhesive, the adhesion performance of the blended system was better than that of the non-blended system. By blending PVA samples with various degrees of saponification and using them as adhesives, the adhesive performances of wood with poor bonding capacity can be greatly improved.
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