Time filter

Source Type

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.


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.


Nakamura Y.,Osaka Institute of Technology | Nakano S.,Osaka Institute of Technology | Ito K.,Osaka Institute of Technology | Imamura K.,Osaka Institute of Technology | And 3 more authors.
Journal of Adhesion Science and Technology | Year: 2013

In this study, the adhesion properties of polyurethane (PUR) pressure-sensitive adhesive (PSA) were investigated. The PUR-PSA was prepared by the cross-linking reaction of a urethane polymer consisting of toluene-2,4-diisocyanate and poly(propylene glycol) components using polyisocyanate as a cross-linking agent. The peel strength increased with the cross-linking agent content and exhibited cohesive failure until the maximum value, after which it decreased with interfacial failure. The PUR-PSA exhibited frequency dependence of the storage modulus obtained from dynamic viscoelastic measurements, but did not show dependence of the tack on the rolling rate measured using a rolling cylinder tack test under the experimental conditions used, which is quite different from the acrylic block copolymer/tackifier system. The PUR-PSA showed strong contact time dependence of tack measured by a probe tack test. The tendency was significantly larger than for the acrylic block copolymer/tackifier system. Therefore, the storage modulus increased, whereas the interfacial adhesion seems to be decreased with increase in the rolling rate for this PUR-PSA system. It was estimated that the influence of rolling rate on the interfacial adhesion and the storage modulus was offset, and, as a result, the rolling cylinder tack did not exhibit rate dependency. © 2012 Taylor & Francis.


Nakamura Y.,Osaka Institute of Technology | Nishida Y.,Osaka Institute of Technology | Fukuda T.,Osaka Institute of Technology | Fujii S.,Osaka Institute of Technology | Sasaki M.,Nitto Analytical Techno Center Co.
Journal of Applied Polymer Science | Year: 2013

Spherical silica particles were treated with a mixture of silane coupling agents with mercapto functional groups and dialkoxy or trialkoxy groups. The surface coverage, which indicates the number of layers covering the silica surface, was in the range from 1.6 to 6.0. The molecular mobility of the treated layer was analyzed with 1H-NMR spectroscopy. The silane chain became more flexible with increasing dialkoxy structures in the mixture and with increasing surface coverage. The stress-strain behavior was measured for a composite consisting of the treated silica and vulcanized polyisoprene rubber (PIR). There was no influence of the dialkoxy and trialkoxy mixing ratio for near monolayer coverage. In the case of the pure dialkoxy and low trialkoxy contents, a higher stress was observed at the same strain for surface coverages of 2.4-3.8. However, a longer length flexible silane chain, that is, with a surface coverage of 6.0, was disadvantageous for the reinforcement effect. The results of pulse NMR analysis of the unextracted PIR on the particle surface and swelling test indicate that the reinforcement effect was strongly affected both by entanglement and the crosslinking reaction between the silane chain and PIR at the interfacial region. Copyright © 2012 Wiley Periodicals, Inc.


Fukuda T.,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 Applied Polymer Science | Year: 2013

Polysulfide-type silane coupling agents containing two or four sulfur atoms were incorporated into a styrene-butadiene rubber/silica composite by two different loading methods and the tensile properties were measured. The pretreatment method and the integral blend method were compared. To improve the 200% modulus of the composite, the combination of silane with four sulfur atoms and the pretreatment method was effective. Whereas, the combination of silane with four sulfur atoms and the integral blend method was effective for improving the fracture elongation. The fracture elongation of the integral blend using the silane with four sulfur atoms was higher than that of the untreated silica-filled composite. The sulfur atoms in the silane should contribute to the crosslinking of rubber in the vulcanization process. The silane with much sulfur atoms strengthens the interface effectively and raises the 200% modulus in the pretreatment method. It is considered that the unreacted silane molecules in the rubber acted as a plasticizer in the integral blend method and the effect was better with four sulfur atoms. The 1H pulse nuclear magnetic resonance spectroscopy was measured for the unvulcanized rubber/silica mixture. The measured relaxation time was found to be in good correlation with the 200% modulus. It was found that the molecular mobility of rubber is lowered by the entanglement with the silane chains on the silica surface at the interfacial region, and it was more effective in the pretreatment method than in the integral blend method. © 2013 Wiley Periodicals, Inc.


Nakamura Y.,Osaka Institute of Technology | Imamura K.,Osaka Institute of Technology | Ito K.,Osaka Institute of Technology | Nakano S.,Osaka Institute of Technology | And 4 more authors.
Journal of Adhesion Science and Technology | Year: 2012

The adhesion strength of an adhesive is affected by two factors: the development of interfacial adhesion and the cohesive strength of the adhesive. In order to evaluate the relative contributions of these two factors, the tack of polyacrylic block copolymer-based adhesives was measured using a probe tack test. For this purpose, three model adhesives were prepared: poly(methyl methacrylate)-block-poly(n-butyl acrylate)-block-poly(methyl methacrylate) triblock copolymer (A), a mixture of the triblock and poly(methyl ethacrylate)-block-poly(n-butyl acrylate) diblock copolymer (7/3, w/w) (B), and a mixtureof the triblock and poly(n-butyl acrylate) oligomer (8/2, w/w) (C). The tack measured at room temperature was in the order B C > A and increased gradually with an increase in the contact time. The temperature dependence of tack showed peak tack values above room temperature, and the peak tack temperature was in the order A > B > C. The storage and loss moduli measured by dynamic mechanical analysis were also in the order A > B > C. The molecular mobility of the poly(n-butyl acrylate) unit in the block copolymer measured by H-pulse NMR was in the order C> B > A. It was concluded from these results that the relative contribution of interfacial adhesion to the tack of the different systems was in the order C > B > A. © 2012 Copyright Taylor and Francis Group, LLC.


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.


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.


Nakamura Y.,Osaka Institute of Technology | Adachi M.,Osaka Institute of Technology | Kato Y.,Osaka Institute of Technology | Fujii S.,Osaka Institute of Technology | And 3 more authors.
Journal of Adhesion Science and Technology | Year: 2011

Effects of polystyrene block content on adhesion property and phase structure of polystyrene block copolymers were investigated. Polystyrene-block-polyisoprene-block-polystyrene triblock and polystyrene-block-polyisoprene diblock copolymers with different polystyrene block contents in the range from 13 to 35 wt% were used. In the case of the low polystyrene block content (below 16 wt%), a sea-island structure was observed: near-spherical polystyrene domains having a mean diameter of about 20 nm were dispersed in polyisoprene matrix. The phase structure changed from a sea-island structure to a cylindrical structure with an increase of polystyrene block content (over 18 wt%). Peel strength decreased with an increase of polystyrene block content and the pure triblock copolymers had lower peel strength than their blends with the diblock copolymers. Pulse nuclear magnetic resonance studies indicated that molecular mobility of polyisoprene phase decreased with an increase of polystyrene block content, and the molecular mobility was lower in the pure triblock than in the blend. Thus, the peel strength was found to be related to molecular mobility. The adhesion strength of the block copolymer depended on the molecular mobility: high molecular mobility can promote interfacial adhesion. © 2011 Koninklijke Brill NV, Leiden.


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.

Loading Nitto Analytical Techno Center Co. collaborators
Loading Nitto Analytical Techno Center Co. collaborators