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Hasegawa M.,Toho University | Fujii M.,Toho University | Ishii J.,Toho University | Yamaguchi S.,Iwatani Industrial Gases Corporation | And 3 more authors.
Polymer (United Kingdom) | Year: 2014

A novel cycloaliphatic monomer for polyimides (PI), 1S,2S,4R,5R- cyclohexanetetracarboxylic dianhydride (H′-PMDA) is proposed in this work. H′-PMDA shows high polymerizability with various diamines in contrast to its isomer, i.e., conventional hydrogenated pyromellitic dianhydride (H-PMDA) and leads to highly flexible and colorless PI films with very high T g's. In particular, the combinations with rigid structures of diamines give rise to PIs with significantly decreased coefficients of thermal expansion (CTE) owing to high extents of in-plane chain orientation induced by thermal imidization, whereas the H-PMDA-based counterparts do not. The decreased CTE reflects structural rigidity/linearity of the H′-PMDA-based diimide units as supported by liquid crystallinity observed in the corresponding model compound. Solution casting of a chemically imidized PI derived from H′-PMDA and 2,2′-bis(trifluoromethyl)benzidine (TFMB) results in a lower CTE than that of the thermally imidized counterpart, suggesting the presence of a self-orientation phenomenon during solvent evaporation. The mechanism is proposed in this work. H′-PMDA/TFMB and its copolymer systems can be useful as plastic substrates in image display devices and/or novel coating-type optical compensation films. © 2014 Elsevier Ltd. All rights reserved.


Hasegawa M.,Toho University | Hirano D.,Toho University | Fujii M.,Toho University | Haga M.,Toho University | And 4 more authors.
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2013

This work presents novel colorless polyimides (PIs) derived from 1R,2S,4S,5R-cyclohexanetetracarboxylic dianhydride (H″-PMDA). Isomer effects were also discussed by comparing with PI systems derived from conventional hydrogenated pyromellitic dianhydride, that is, 1S,2R,4S,5R-cyclohexanetetracarboxylic dianhydride (H-PMDA). H″-PMDA was much more reactive with various diamines than H-PMDA, and the former led to PI precursors with much higher molecular weights. The results can be explained from the quite different steric structures of these isomers. The thermally imidized H″-PMDA-based films were colorless regardless of diamines because of inhibited charge-transfer interaction. In particular, the H″-PMDA/4, 4′-oxydianiline system simultaneously achieved a very high Tg exceeding 300 °C, high toughness (elongation at break > 70%), and good solution processability. In contrast, the H-PMDA-based counterparts were essentially insoluble. The outstanding solubility of the former probably results from disturbed chain stacking by its nonplanar steric structure. An advantage of chemical imidization process is also proposed. In some cases, a copolymerization approach with an aromatic tetracarboxylic dianhydride was effective to improve the thermal expansion property. The results suggest that the H″-PMDA-based PI systems can be promising candidates for novel high-temperature plastic substrate materials in electronic paper displays. A potential application as optical compensation film materials in liquid crystal displays (LCD) is also proposed in this work. © 2012 Wiley Periodicals, Inc.


Morioka T.,Japan National Institute of Advanced Industrial Science and Technology | Ito M.,Iwatani Industrial Gases Corporation | Fujikawa S.,Iwatani Industrial Gases Corporation | Ishibashi M.,Japan National Institute of Advanced Industrial Science and Technology | Nakao S.-I.,Flow Col
Flow Measurement and Instrumentation | Year: 2014

The calibration facility with the multi-nozzle calibrator was developed for the calibration of flow meters to be used with high-pressure, high-flow-rate hydrogen gas. The critical nozzles installed in the multi-nozzle calibrator were calibrated with traceability to the national standard. The relative standard uncertainty of the mass flow rates produced from the calibration facility is 0.09% when the flow rate is between 150. g/min and 550. g/min. In this study, the Coriolis flow meter was calibrated for a pressure range of 15-35. MPa. The relative standard uncertainty of the flow rates obtained from the Coriolis flow meter was 0.44% for the case of the worst fluctuations in the output of the flow meter; based on the calibration curve, this is 0.91%. The present result shows that there is a maximum 3% difference between the output of the Coriolis flow meter and the mass flow rates of the multi-nozzle calibrator, even though the Coriolis flow meter was calibrated using water. Therefore, for the development of a calibration facility that can calibrate a flow meter under the same conditions as those encountered in actual use, it will be important to develop a new flow meter. © 2014 Elsevier Ltd.


Hata T.,Osaka City University | Matsumoto T.,Osaka City University | Obara K.,Osaka City University | Yano H.,Osaka City University | And 4 more authors.
Journal of Low Temperature Physics | Year: 2014

Dilution refrigerators are an important tool used in solid state and quantum fluid physics for cooling to temperatures below 0.3 K. Conventional dilution refrigerators consume a lot of liquid helium, which has to be recharged in a helium bath every few days. Cryogen-free dilution refrigerators, however, do not use liquid helium and then automatic operation by electricity can be possible from room temperature to the mK region. In near future, therefore, most conventional dilution refrigerators will be replaced by cryogen-free refrigerators because they are easy to operate, do not require maintenance and do not consume helium. We have developed two types of cryogen-free dilution refrigerator. One is directly cooled by a pulse tube refrigerator in the same cryostat using copper thin wires as a thermal link, and the other is cooled by a separate Gifford McMahon refrigerator using circulating helium gas through a flexible syphon tube. The latter has been developed as a vibration-free cryogen-free dilution refrigerator. These two types of cryogen-free dilution refrigerator are compared considering several key points: base temperature, precooling time, minimum temperature and vibration amplitude. © 2013 Springer Science+Business Media New York.


Takeda M.,Kobe University | Yagi S.,Kobe University | Matsuno Y.,Iwatani Industrial Gases Corporation | Kodama I.,Iwatani Industrial Gases Corporation | And 3 more authors.
AIP Conference Proceedings | Year: 2010

To develop basic technologies for the maritime transport of hydrogen energy, a liquid hydrogen experiment facility (LHEF) with system enabling observation under horizontal vibration has been designed and constructed. The LHEF consists of a liquid hydrogen optical cryostat, a gas-handling system, vacuum pumps, and apparatus for generating horizontal vibrations. The liquid hydrogen optical cryostat, which is 1200 mm in height and 300 mm in diameter, includes a vacuum jacket, a liquid nitrogen space (10.0 liters), a liquid hydrogen space (13.6 liters), a sample space (3.8 liters), optical windows, and a needle valve. The results of performance tests show that the heat leak in the liquid hydrogen space is sufficiently small. Using the LHEF under horizontal vibration, the damped oscillation of the liquid hydrogen surface is successfully observed and analyzed on the basis of a simple model. © 2010 American Institute of Physics.


Haruyama T.,High Energy Accelerator Research Organization | Kasami K.,High Energy Accelerator Research Organization | Nishitani T.,Iwatani Industrial Gases Corporation
AIP Conference Proceedings | Year: 2010

An experimental study to improve the cooling power of a coaxial pulse tube cryocooler (PTC) has been carried out. The operating temperature was optimized for cooling liquid xenon at around 165-170 K. The PTC has a coaxial configuration with a cylindrical regenerator inside, a hollow-walled cylindrical pulse tube. The cooling performance obtained was ∼180-200 W at around 165 K, when operated with a 6-6.5 kW GM-type compressor. For the phase shift between pressure and flow, a simple-orifice scheme was used, which resulted in stable operation of a long-term physics experiment. PTCs have now been successfully applied in physics experiments such as MEG and XENON for many years. In order to study flow disturbance inside of a tube, thermometers were placed on an outer cylinder wall to monitor gas temperature inside of a tube. In the original scheme, there is a single gas exhaust line from the pulse tube to an orifice valve and buffer tank. In this study, an additional exhaust line was used to suppress the flow disturbance in such a pulse tube. Also, the cooling power dependence on the regenerator was experimentally studied by changing the mesh size and the length of the regenerator. © 2010 American Institute of Physics.


Otaka T.,Kokushikan University | Ito M.,IWATANI Industrial Gases Corporation
American Society of Mechanical Engineers, Power Division (Publication) POWER | Year: 2011

The green house effect by carbon dioxide issue would make better recognizing the importance of efficient use of energy in terms of high energy conservation measures. Accordingly, attention is drawn to the Stirling cycle machine, which is a perfect Freon free and efficient machine. Most Stirling engines operate in temperature ranges in which the temperature difference between the heat source and heat sink is between 100 K and 700 K, with the room temperature being at the lower end of the operating temperature range. However, information available on engines that utilize the room temperature as the heat source and the ultra-low temperature of liquid nitrogen as the heat sink is scarce. Engines that operate within such temperature ranges are called cryogenic heat engines. If their practical applications are realized, energy that has hitherto been wasted during the use of ultra-low-temperature media can be recovered in the form of electrical energy. We have designed and developed a 500 W class Stirling machine as a cryogenic engine. This paper presents some operating characteristics. Copyright © 2011 by ASME.

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