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Isobe N.,University of Tokyo | Sekine M.,Saitama Industrial Technology Center | Kimura S.,University of Tokyo | Wada M.,University of Tokyo | And 2 more authors.
Cellulose | Year: 2011

Cellulose-synthetic polymer nanocomposite films were prepared by immersion of cellulose gel in polymer solutions followed by dry casting. The cellulose hydrogel was prepared from aqueous alkali-urea solution. As the synthetic polymer, polystyrene (PS) and poly(methyl methacrylate) (PMMA) were used. The polymer content could be changed between 10 and 80% by changing polymer concentration of immersing solution. While the mechanical properties of the cellulose-PMMA composite films showed a nearly linear dependence on PMMA content, those of cellulose-PS composites showed an anomalous behavior; both tensile strength and Young's modulus showed prominent maxima at 15-30 wt% PS contents. This anomaly may have resulted from the specific interaction between the aromatic ring of PS and the hydrophobic plane of the glucopyranoside. Both PMMA and PS composite films showed significant improvements in dimensional thermal stability; up to 25 wt% synthetic polymer content, the coefficient of thermal expansion (CTE) was as low as ca. 30 ppm/K, about 1/3 of the pure polymers. This indicates that the regenerated cellulose network is effective in suppressing thermal expansion of the synthetic polymers. © 2011 Springer Science+Business Media B.V.

Aogaki R.,Kanagawa University | Morimoto R.,Saitama Industrial Technology Center | Asanuma M.,Yokohama Polytechnic College
Journal of Magnetism and Magnetic Materials | Year: 2010

In copper electrodeposition under a magnetic field parallel to electrode surface, different roles of two kinds of nonequilibrium fluctuations for micro-magnetohydrodynamic (MHD) effects are discussed; symmetrical fluctuations are accompanied by the suppression of three dimensional (3D) nucleation by micro-MHD flows (the 1st micro-MHD effect), whereas asymmetrical fluctuations controlling 2D nucleation yield secondary nodules by larger micro-MHD flows (the 2nd micro-MHD effect). Though the 3D nucleation with symmetrical fluctuations is always suppressed by the micro-MHD flows, due to the change in the rate-determining step from electron transfer to mass transfer, the 2D nucleation with asymmetrical fluctuations newly turns unstable, generating larger micro-MHD flows. As a result, round semi-spherical deposits, i.e., secondary nodules are yielded. Using computer simulation, the mechanism of the 2nd micro-MHD effect is validated. © 2009 Elsevier B.V. All rights reserved.

Yamada T.,Saitama Industrial Technology Center | Murata Y.,Nippon Institute of Technology | Yokoi H.,University of Tokyo
International Polymer Processing | Year: 2012

In this study, cross-sectional analyses were performed on microcellular injection-molded high-impact polystyrene products. The results confirm that the following five types of layers were formed: Skin layers I (the silver streak layer) and II (a nonfoamed layer), Core layers I (cell diameter, d > 150 lm), II (d < 50 lm), and III (d > 100 lm). As the maximum in-mold pressure (Pmax) was increased from 5 to 30 MPa, the thickness of Skin layer II remained nearly constant. However, the foam types in the core layers changed from I and II to II and III or III only, resulting in an increase in cell diameter and a decrease in cell density. The process of cellular structure formation was observed using a glass-inserted mold, which revealed that this process consists of a flow (with a burst of cells at the melt front and the subsequent flow of the melt containing the cells), an end of the filling (involving elastic compression or the dissolution and disappearance of cells formed in the flow stage), and a cooling (new cell generation and growth and cooling solidification). Based on these cross-sectional observations, in concert with meltpressure measurements and visualizations, we developed a model describing the formation process of Skin layer II and the core layers including a new concept that considers the melt pressure inside the cavity. The following layers are incorporated into the model: Skin layer II: A nonfoamed layer is formed in the area of the melt front where gases diffuse out from within the melt during the filling stage, and this nonfoamed layer moves to from melt front to the surface of the product due to fountain flow. Core layers I and II: A multilayer is formed containing a distribution of cells preserved from the flow stage due to the low compression forces, Core layer III: cells are dissolved in the melt due to strong compression forces at the end of the filling stage and then reform and grow in the cooling stage. © Carl Hanser Verlag, Munich Intern.

Sano M.,Saitama Industrial Technology Center | Sano M.,Tokyo Institute of Technology | Oguma H.,Saitama Industrial Technology Center | Sekine M.,Saitama Industrial Technology Center | And 2 more authors.
International Journal of Adhesion and Adhesives | Year: 2014

In this study, high-frequency (HF) welding of glass-fiber-reinforced polypropylene (GF/PP) was investigated with thermoplastic adhesive layers including SiC, which is able to heat by HF irradiation. The influences of SiC particle size and content on the dielectric properties of an adhesive layer were investigated experimentally. The influence of temperature on the tan δ/ε′ value was also investigated. In the HF welding process of GF/PP bonded with the thermoplastic adhesive layer, the effects of SiC content and particle size on the welding properties were examined. The GF/PP was completely welded in a short time when SiC with small particle size and high content was included in the adhesive and a good bond strength was also achieved. Thus, short time and high bond strength for the welding were achieved with the method using a thermoplastic adhesive layer with high tan δ/ε′ value. © 2014 Elsevier Ltd.

Iizuka S.,Saitama Industrial Technology Center | Murata K.,Saitama Industrial Technology Center | Sekine M.,Saitama Industrial Technology Center | Sekine M.,Waseda University | Sato C.,Tokyo Institute of Technology
Polymer Testing | Year: 2016

Water vapor transmission rate (WVTR) measurements with the conventional cup method do not yield accurate values at high temperatures because the film specimens deform and are damaged owing to air expansion in the cup. A new cup with a pressure-adjusting mechanism allows measurements at 85°C and prevents specimen deformation and damage. WVTRs of polypropylene (PP) and polyethylene terephthalate (PET) measured with the new cup method are the same as those measured with the conventional cup method at 40°C, and gas chromatographic detection method at 60°C and 85°C. Arrhenius plots of the water vapor permeability coefficient of PP, polyethylene naphthalate (PEN) and polyimide (PI) with the new cup method show a linear relationship in the range 25-85°C. In the same range, Arrhenius plots of PET, polybutylene terephthalate (PBT) and polylactic acid (PLA) have bending points corresponding to the glass transition temperatures of the materials. © 2015 Elsevier Ltd. All rights reserved.

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