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Sasaki M.,Nitto Analytical Techno Center Co. | Adachi M.,Osaka Institute of Technology | Kato Y.,Osaka Institute of Technology | Fujii S.,Osaka Institute of Technology | And 3 more authors.
Journal of Applied Polymer Science | Year: 2010

Relationship between adhesion properties and phase structures of styrene triblock and diblock copolymer blends was investigated in detail. For this purpose, polystyrene-block-polyisoprene-block-polystyrene triblock and polystyrene-block-polyisoprene diblock copolymers were used and the diblock content was varied from 0 to 100 wt %. All blends formed the sea-island structure in which spherical polystyrene domains were dispersed in polyisoprene matrix and mean domain size was ̃ 20 nm. The domain size was slightly affected by the diblock content. The fracture stress and strain measured by a tensile test decreased and the molecular mobility measured by a1H pulse nuclear magnetic resonance analysis increased with an increase of diblock content. The tack as adhesion property increased with an increase of diblock content below 70 wt %, then decreased over 70 wt %. The cohesive strength decreased and the interfacial adhesion increased with an increase of diblock content. The tack increases by the development of cohesive strength and interfacial adhesion. Therefore, the tack showed the maximum at the optimum contribution balance between cohesive strength and interfacial adhesion. © 2010 Wiley Periodicals, Inc. Source


Nakamura Y.,Osaka Institute of Technology | Nishida Y.,Osaka Institute of Technology | Honda H.,Osaka Institute of Technology | Fujii S.,Osaka Institute of Technology | Sasaki M.,Nitto Analytical Techno Center Co.
Journal of Adhesion Science and Technology | Year: 2011

The surface treatment of spherical silica particles with silane coupling agent having mercapto group was carried out and structure and amount of silane nanolayer formed on silica surface were analyzed using 1H pulse nuclear magnetic resonance (NMR) and thermogravimetric analysis, respectively. Effects of loading amount and number of alkoxy groups of silane on the structure were investigated. Silanes with dialkoxy and trialkoxy structures were used as silane coupling agents and the loading amount of the silane on the silica surface was varied from one to nine times the amount required for monolayer coverage. The relaxation time was longer in the dialkoxy type than in the trialkoxy type of silane. The relaxation time increased with increase of the loading amount of silane for the dialkoxy type; on the other hand, there was no influence of the loading amount of silane for the trialkoxy type. It was found that the silane structure was flexible for the dialkoxy type, whereas it was rigid for the trialkoxy type. Effect of mixing ratio of silane coupling agents having di- and trialkoxy groups on the silane nanolayer structure was also investigated, and 1H pulse NMR studies confirmed that the relaxation time measured for the mixed silane-treated system was between those for the dialkoxy and the trialkoxy structures and depended on the mixing ratio. It was found that the network density of silane-treated layer on silica particles could be controlled by varying the molar ratio of dialkoxy/trialkoxy silane coupling agents. © 2011 Copyright Taylor and Francis Group, LLC. Source


Yamasaki H.,Nitto Analytical Techno Center Co. | Morita S.,Osaka Electro-Communication University
Journal of Molecular Structure | Year: 2015

The isothermal curing reaction of bisphenol A diglycidyl ether epoxy (BADGE) resin with dimethyl diamino methane (DDM) hardener was investigated by means of modulated differential scanning calorimetry (MDSC) and infrared (IR) spectroscopy at 90, 100 and 120 °C.It was confirmed that the behavior of the bands assigned to the epoxy group, ether group, secondary amine and tertiary amine were different depending on temperature. At stoichiometric amounts of DDM and BADGE, the reaction at 90 and 100 °C compared with that at 120 °C, the oxirane or glycidyl group of epoxy resin and the secondary amine group were left even if reached at the end point of the reaction, and those reaction proceed as diffusion control continues longer. The reaction between 90 and 100 °C, it was different from the reactivity of the epoxy resin, various amino groups and ether group. Hence, the cured epoxy resin had a different composition. Moreover, it was also verified that the reactivity of the various amino groups and the etherification were difference, therefore, it was suggested that the cross-linkage construction of the cured resin at different temperature was different. © 2015 Elsevier B.V. Source


Nakamura Y.,Osaka Institute of Technology | Adachi M.,Osaka Institute of Technology | Ito K.,Osaka Institute of Technology | Kato Y.,Osaka Institute of Technology | And 4 more authors.
Journal of Applied Polymer Science | Year: 2011

The effects of compatibility of tackifier with polymer matrix and mixing weight ratio of triblock/diblock copolymers as the matrix on the adhesion property and phase structure of tackifier-added polystryrene triblock/diblock copolymer blends were investigated. For this purpose, polystyrene-block- polyisoprene-block-polystyrene triblock and polystyrene-block-polyisoprene diblock copolymers were used and the diblock weight ratio in the blend was varied from 0 to 1. Spherical polystyrene domains with a mean size of about 20 nm were dispersed in the polyisoprene (PI) continuous phase. In the case of the hydrogenated cycloaliphatic resin as tackifier having a good compatibility with PI and a poor compatibility with polystyrene, the peel strength increased with an increase of the tackifier content, and the degree of increase became significant above 40 wt % of tackifier. It was found that the nanometer-sized agglomerates of tackifier in the PI matrix were formed and the distance between the nearest neighbors of agglomerates was about 15 nm from SAXS measurement. The peel strength increased with an increase of the nanometer-sized agglomerates of tackifier from TEM observation. On the other hand, in the case of the rosin phenolic resin as tackifier having a good compatibility with both polystyrene and PI, the peel strength increased effectively at the lower tackifier content, while no significant increase at higher tackifier content was observed. The agglomerates of tackifier were never confirmed in this system. The higher peel strength was obtained at the diblock weight ratio in the blend of 0.5-0.7 for both tackifier-added systems. © 2010 Wiley Periodicals, Inc. Source


Fukuda T.,Osaka Institute of Technology | Yamazaki R.,Osaka Institute of Technology | Fujii S.,Osaka Institute of Technology | Nakamura Y.,Osaka Institute of Technology | Sasaki M.,Nitto Analytical Techno Center Co.
Journal of Adhesion Science and Technology | Year: 2013

The surface treatment of spherical silica particles using a silane coupling agent with a glycidoxy group was conducted and the effect of the alkoxy group number on the molecular mobility of the silane chain was investigated by 1H pulse nuclear magnetic resonance (NMR). Silanes with di-alkoxy and tri-alkoxy structures were used, and the silica particles were treated with 2-propanol solution and heated at 120°C for 24 h after solvent evaporation. The surface coverage of the silica surface was in the range from two to three layers. For multilayer coverage, linear chain and network structures were expected to form on the surface by polycondensation reaction using the di- and tri-alkoxy structures, respectively. However, the relaxation times for silane chains with both di- and tri-alkoxy structures measured by pulse NMR were short, which indicates that both silane chains formed rigid network structures. Fourier transform infrared spectroscopic analysis revealed that ring opening of the epoxy group occurred, followed by reaction to form the network structure, even with the di-alkoxy structure. Ring opening of the epoxy group could be reduced by setting the heating temperature at 80°C. There was a significant difference in flexibility between the silane-layers with di- and tri-alkoxy structures after heating at 80°C, as reflected by the relaxation time. © 2012 Taylor & Francis. Source

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