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61.
Yosuke Kimura Masaharu Asano Ryoichi Katakai 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,263(2):463-467
Poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated by swift heavy ion-beams of 129Xe23+ with fluences of 0, 3 × 106, 3 × 107, 3 × 108 and 3 × 109 ions/cm2, followed by γ-ray pre-irradiation for radiation grafting of styrene onto the ETFE films and sulfonation of the grafted ETFE films to prepare highly anisotropic proton-conducting membranes. The fluence of Xe ions and the addition of water in the grafting solvent were examined to determine their effect on the proton conductivity of the resultant membranes. It was found that the polymer electrolyte membrane prepared by grafting the styrene monomer in a mixture of 67% isopropanol and 33% water to the ETFE film with an ion-beam irradiation fluence of 3.0 × 106 ions/cm2 was a highly anisotropic proton-conducting material, as the proton conductivity was three or more times higher in the thickness direction than in the surface direction of the membrane. 相似文献
62.
63.
Takeshi Kikutani J. Radhakrishnan Sadaaki Arikawa Akira Takaku Norimasa Okui Xia Jin Fumio Niwa Yosuke Kudo 《应用聚合物科学杂志》1996,62(11):1913-1924
High-speed bicomponent spinning of poly(ethylene terephthalate)(PET)(core) and poly-propylene (PP) (sheath) was carried out and the structure development in the individual components, PET and PP, was investigated. The orientation and crystallinity development in the PET component was enhanced as compared to that of the single-component spinning while the PP component remained in a low orientation state and had a pseudohexagonal crystal structure even at high take-up speeds. To clarify the mutual interaction between the two components in bicomponent spinning, a semiquantitative numerical simulation was performed. The simulation results obtained using the Newtonian fluid model showed that the solidification stress in the PET component was enhanced while that of the PP component was decreased in comparison with the corresponding single-component spinning. This is due to the difference in the temperature dependence of their elongational viscosity. Simulation with an upper-convected Maxwell model as the constitutive equation suggested that significant stress relaxation of the PP component can occur in the spinline if the PET component solidifies earlier than does PP. Based on the structural characterization results, and the simulation results, it was concluded that the difference in the activation energy of the elongational viscosity and solidification temperature between the two polymers are the main factors influencing the mutual interaction in the bicomponent spinning process. © 1996 John Wiley & Sons, Inc. 相似文献
64.
ABSTRACT Thin-layer re-wetting experiments were conducted with medium grain rough rice in the temperature range of 17.8 to 45°C and for relative humidities between 56 and 89.3%, with initial moisture contents in the range of 10.26 to 12.71% dry-basis to determine the diffusion coefficient of rough rice. Recent efforts to characterize the re-wetting characteristics of rough rice are summarized. New equation for temperature dependent liquid diffusion coefficients for medium grain rough rice are presented. The diffusion coefficient in re-wetting was lower than the drying. The results presented here, over typically five day re-wetting, will be useful in studying the longer term moisture transfer process occurring during ventilated storage. 相似文献
65.
Yoshiyuki Abe Kazuyuki Kakegawa Yoshinori Sasaki 《Journal of the American Ceramic Society》1992,75(1):234-236
A complex perovskite of Sr(Cu x Zn1- x )1/2 W1/2 O3 (SCZW) is synthesized by a new combination of wet and dry processess. Mixed oxides containing Cu2+ and Zn2+ (CZ) are prepared by the wet process (coprecipitate method). SCZW is obtained by the dry process (mixed-oxide method) from a mixture of CZ, SrCO3 , and WO3 . SCZW has practically no compositional, unlike solid solutions prepared by the conventional dry method. The wet–dry process method is useful because the wet process is applied to only B-site cations having the same valence. 相似文献
66.
Porous glass-ceramics with a skeleton of the fast-lithium-conducting crystal Li1+ x Ti2− x Al x (PO4 )3 (where x = 0.3–0.5) were prepared by crystallization of glasses in the Li2 O─CaO─TiO2 ─Al2 O3 –P2 O5 system and subsequent acid leaching of the resulting dense glass-ceramics composed of the interlocking of Li1+ x Ti2− x Al x (PO4 )3 and β-Ca3 (PO4 )2 phases. The median pore diameter and surface area of the resulting porous Li1+ x Ti2− x Al x (PO4 )3 glass-ceramics were approximately 0.2 μm and 50 m2 /g, respectively. The electrical conductivity of the porous glass-ceramics after heating in LiNO3 aqueous solution was 8 × 10−5 S/cm at 300 K or 2 × 10−2 S/cm at 600 K. 相似文献
67.
Carbon materials are often used as catalyst supports, and for catalysts in electrodes of a polymer electrolyte fuel cell, carbon black has been used. Recently, it was found, however, that activated carbon could replace carbon black and besides, significantly improve the activity of the electrode catalyst layer for oxygen reduction. In the present study, to optimize the pore structure of activated carbon for further activity improvement, the influence of the pore structure on the activity was investigated using activated carbon of various specific surface areas and mean pore diameters. A catalyst layer was formed from activated carbon loaded with platinum and a polymer electrolyte. The activity of the layer was measured in an oxygen-saturated perchloric acid solution, supporting the layer on a rotating glassy carbon disk electrode. We found that increases in the specific surface area and mean pore diameter increased the activity and that the latter was more effective than the former mainly due to the enhanced mass-transfer in the pores; the catalyst layer formed from activated carbon with the largest mean pore diameter was the most active. Unless pores excessively develop and lose connections between particles, a large pore diameter is therefore desired for the fuel cell electrodes. 相似文献
68.
Songlan Yang Zheng Ming Sun Hitoshi Hashimoto Toshihiko Abe 《Journal of the European Ceramic Society》2003,23(16):3147-3152
In this study, free 2Ti/2Si/3TiC powder mixture was heated at high temperatures in vacuum, in order to reveal the possibility for the synthesis of high Ti3SiC2 content powder. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for the evaluation of phase identities and the morphology of the powder after different treatments. Results showed that almost single phase Ti3SiC2 powder (99.3 wt.%) can be synthesized by heat treatment with free 2Ti/2Si/3TiC powders in vacuum at 1210°C for about 3 h. The nucleation and growth of Ti3SiC2 within TiC particles was observed. The typical appearance of the formed Ti3SiC2 is equiaxed with particle size of 2–4 μm. Effects of temperature and heating time on the morphology and the particle sizes of the synthesized Ti3SiC2 powders are not obvious. 相似文献
69.
Zhe-Feng Zhang Zheng Ming Sun Hitoshi Hashimoto Toshihiko Abe 《Journal of the American Ceramic Society》2003,86(3):431-436
Ti/Si/2TiC powders were prepared using a mixture method (M) and a mechanical alloying (MA) method to fabricate Ti3 SiC2 at 1200°–1400°C using a pulse discharge sintering (PDS) technique. The results showed that the Ti3 SiC2 samples with <5 wt% TiC could be rapidly synthesized from the M powders; however, the TiC content was always >18 wt% in the MA samples. Further sintering of the M powder showed that the purity of Ti3 SiC2 could be improved to >97 wt% at 1250°–1300°C, which is ∼200°–300°C lower than that of sintered Ti/Si/C and Ti/SiC/C powders using the hot isostatic pressing (HIPing) technique. The microstructure of Ti3 SiC2 also could be controlled using three types of powders, i.e., fine, coarse, or duplex-grained, within the sintering temperature range. In comparison with Ti/Si/C and Ti/SiC/C mixture powders, it has been suggested that high-purity Ti3 SiC2 could be rapidly synthesized by sintering the Ti/Si/TiC powder mixture at relatively lower temperature using the PDS technique. 相似文献
70.
Katsuhiro Inomata Daisuke NakanishiAi Banno Eiji NakanishiYosuke Abe Ryuta KuriharaKentaro Fujimoto Takuhei Nose 《Polymer》2003,44(18):5303-5310
Association behavior and physical gelation mechanism of ABA triblock copolymer dissolved in B-selective solvent have been studied systematically from dilute to moderately concentrated solutions. Static and dynamic light scattering and nuclear magnetic resonance measurements for dilute solutions of poly(methyl methacrylate)-block-poly(tert-butyl acrylate)-block-poly(methyl methacrylate) (PMMA-PtBuA-PMMA) in 1-butanol (PtBuA selective solvent) indicated that PMMA-PtBuA-PMMA chains are molecularly dissolved above 50 °C. With decreasing temperature, the triblock copolymers form associated micelles consisting PMMA associated core and PtBuA shell. Linear dynamic viscoelastic measurements for solutions with moderate concentration (3.9-12.0 wt%) revealed that the system was viscous sol state at 60 °C. Drastic increase of shear storage modulus (G′) occurred with decreasing temperature, and at 25 °C, G′ showed rubbery plateau with weak frequency dependency, means the formation of elastic physical gel. The consistency between the temperature for micelle formation and that at the increase in G′ indicates that the physical gelation is owing to the network formation as the result of the association of PMMA chains and the bridging PtBuA chains connecting the PMMA cores. Master curves for the dynamic moduli were derived by time-temperature superposition along the frequency axis. Just above sol-gel transition concentration (Cgel), the master curves suggest the existence of fairy amount of aggregate that is not incorporated in the macroscopic network. With the increase in polymer concentration, the master curves become to reveal Maxwell-type viscoelasticity with narrow relaxation time distribution, suggesting the formation of transient network with easily generation and destruction of crosslinks. Concentration dependency of the plateau modulus is stronger than the theoretically expected, means the macroscopic transient network grows with polymer concentration by increasing the fraction of elastically effective bridging PtBuA chain above Cgel. 相似文献