Journal of The Adhesion Society of Japan
Online ISSN : 2187-4816
Print ISSN : 0916-4812
ISSN-L : 0916-4812
Volume 54 , Issue 12
Showing 1-4 articles out of 4 articles from the selected issue
Review
  • Hiroaki MURASE, Sakiko FUKUNISHI, Yuki OUCHI
    2018 Volume 54 Issue 12 Pages 466-473
    Published: December 01, 2018
    Released: January 19, 2019
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    Polysilanes, which have silicon-silicon bond chain, have attracted considerable attention due to theirusefulness such as precursors for thermally stable ceramics materials, microlithography and so on. Osaka GasChemicals has found that the reduction of dichlorosilane with Mg metal in the presence of LiCl and Lewis acidwas highly useful synthetic method for polysilanes.This review deals with an applied research of polysilane, that is, the effects of polysilane-coating on theinterface of electrofusion type pipe joint(EF) and polyethylene(PE) pipes. The fusion strength greatlydepends on the amount of sand which adheres to the interface during field works, because there is no flowof melted resin at the fusion interface. It was found that a kind of polysilane on the fusion interface keptthe fusion strength even if there was some amount of sand. The reasons were examined from chemical andphysical points of view. Polysilane molecule permeated into the PE resin deeply and hence the PE resins of thepipe and EF joint are thought to be thoroughly mixed with each other. That effect was also observed in case ofpolypropylene and cycloolefin polymers.

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Review
Comprehensive Paper
  • Mitsuhiro SHIBAYAMA, Yasuyuki SHUDO, Atsushi IZUM
    2018 Volume 54 Issue 12 Pages 451-458
    Published: December 01, 2018
    Released: January 17, 2019
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    Phenolic resins are widely used thermosetting plastics in a variety of industries including the aerospace,automotive, housing, and semiconductor industries. This is because of their excellent properties such ashigh mechanical strength, thermal stability, insulating properties, and solvent resistance that are derivedfrom their highly crosslinked structures. Crosslinked structure and inhomogeneity in cured thermosettingresins are recognized as a key factor in controlling the material properties of thermosetting resins. However,the understanding of the relationship between the structure and physical properties has not been unveiledbecause of its insolubility and infusibility. Recently, we are tackling this problem by using state-of-arttechniques, such as high brilliant small-angle X-ray scattering( SPring-8), neutron scattering( JRR-3 andJ-PARC), and a large-scale molecular dynamics( MD) simulation( K Computer), and so on. This articleoverviews the recent development of the research on the phenolic resins. The structural evolution of phenolicresin during polymerization/crosslinking reactions, the fractal structure, and inhomogeneities of phenolicresins are discussed based on real experiments together with modeled( virtual) phenolic resins created in acomputer by MD simulations.

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Comprehensive Paper
  • Go MATSUBA
    2018 Volume 54 Issue 12 Pages 444-450
    Published: December 01, 2018
    Released: January 12, 2019
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    Poly(lactic acid)(PLA) has been widely used as an alternative to petroleum-based polymers. Commercially,PLA is prepared by the fermentation of lactic acid produced from natural renewable sources such as cornin a typical compost environment. In fact, the synthesis method is environmentally benign with no emissionof carbon dioxide. Although PLA was initially intended for use in biomedical applications, these interestingtechnological features such as ease of polymer processing, good clarity, and acceptable mechanical propertieshave widened its use as a material in packaging, electronic, and automobile applications. However, PLA has aproblem of low thermal and mechanical properties due to low crystallinity. In order to increase the crystallinityof PLA sample, many researchers focused on stereo-complex crystals(Sc) from poly(L-lactic acid) and poly(D-lactic acid) blend. The melting point of Sc is approximately 50℃ higher than α-crystals of PLA. In thisreview, I discussed crystallization of Sc from the glassy state and the molten state and crystallization undershear flow. Time-resolved polarized optical microscopy, DSC, synchrotron radiation X-ray scattering werecarried out. During cooling down from the molten state, several tens micron crystals and 20 nm long spacingperiod were observed, while crystallization from the glassy state, we could observe very small crystals belowthe melting point of α-crystals. Furthermore, bimodal long spacing period, 60 and 15 nm because of αlamellarcrystal growth and melting during heating up were observed. Furthermore, this review discussed about theeffect of shear flow imposed prior to crystallization on higher-order structure formation and accelerationof Sc crystal growth. The density fluctuations of 100-nm scale were observed prior to nucleation by in situsimultaneous wide- and small-angle X-ray scattering measurements. These density fluctuations grew with timeand the intensity increased with increasing shear rate. Furthermore, the results revealed that the poly(L-lacticacid) and poly(D-lactic acid) chains were only partially interpenetrated. The strength of density fluctuationprior to nucleation was strongly dependent on the mixed phases.

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