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排序方式: 共有1673条查询结果,搜索用时 17 毫秒
971.
Masayuki Yamaguchi Ken‐Ichi Suzuki Hiroshi Miyata 《Journal of Polymer Science.Polymer Physics》1999,37(7):701-713
The structure and mechanical properties of the injection‐molded products for the binary blends composed of an isotactic polypropylene (PP) and a rubbery ethylene‐1‐hexene copolymer (EHR) were studied. The following two types of blends were employed: one is the incompatible blend of PP and ethylene‐rich EHR; the other is the compatible blend of PP and 1‐hexene‐rich EHR. The incompatible blend shows a phase‐separated morphology, in which EHR domains in the skin layer highly orient to the flow direction. On the other hand, the compatible blend shows fairly homogeneous morphology in the skin and core regions, in which EHR molecules are dissolved into the amorphous PP region. The measurements of birefringence and infrared dichroism revealed that the magnitude of molecular orientation along the flow direction for the compatible blend is larger than that for the incompatible blend. Nevertheless, it was also found that anisotropy of the mechanical properties for the compatible blend is less prominent, which is attributed to lack of the mechanical connection between neighbor crystalline fragments aligned perpendicular to the flow direction. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 701–713, 1999 相似文献
972.
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974.
Masayuki Yamaguchi Hiroshi Miyata Koh-Hei Nitta 《Journal of Polymer Science.Polymer Physics》1997,35(6):953-961
Morphology and isothermal growth rates of spherulites for the binary blends consisting of an isotactic polypropylene (i-PP) and an ethylene-1-hexene rubber (EHR) were examined as a function of the crystallization temperature ranging from 388 K to 418 K. In this study, two types of EHR's were employed: “ethylene rich” EHR and “1-hexene rich” EHR. The blends of i-PP with the EHR of 51 mol % 1-hexene are miscible in the molten state, whereas the blends with the EHR of 33 mol % 1-hexene are immiscible in the molten state. It is found that the isothermal spherulite growth rate of the miscible i-PP/EHR blends decreases with increasing the EHR fraction, whereas the spherulite growth rate of the immiscible i-PP/EHR blends is independent of the blend composition and is the same as that of the i-PP. Optical microscope observation of the miscible blends crystallized isothermally shows that there are no rubber domains either in the intraspherulitic or in the interspherulitic contact regions. On the other hand, the immiscible i-PP/EHR blends show a phase-separated morphology. Furthermore, the number of tangential lamellae of the miscible i-PP/EHR blends is found to be increased by blending of the EHR, leading to the spherulite with negative birefringence. The sign of birefringence of spherulites is unaffected by the regime transition as well as by the fold surface free energy. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 953–961, 1997 相似文献
975.
Nobuhiro Kanomata Masayuki Suzuki Mamiko Yoshida Tadashi Nakata 《Angewandte Chemie (International ed. in English)》1998,37(10):1410-1412
Just like in biological systems , the GAPDH-catalyzed oxidation of aldehyde to carboxylate proceeds in conjunction with 1,4-selective reduction of NAD+ to NADH model compounds [Eq. (1)]. The combination of GAPDH- and LDH-type transfer reactions is also described here as a system mimic for the NAD+/NADH redox cycle in anaerobic glycolysis. GAPDH=D -glyceraldehyde-3-phosphate dehydrogenase, LDH=L -lactate dehydrogenase. 相似文献
976.
Masayuki Inoue Makoto Sasaki Kazuo Tachibana 《Angewandte Chemie (International ed. in English)》1998,37(7):965-969
Exceptional neurotoxicity is associated with ciguatoxin. The ciguatoxin mimic 1 , which contains the F–M framework of the natural product, has been prepared through a convergent synthesis. The two key steps were a Lewis acid mediated intramolecular reaction of a γ-alkoxyallylsilane with an acetal group and an SmI2-mediated intramolecular Reformatsky reaction that permitted construction of the annelated hexahydrooxonin ring system. 相似文献
977.
Takaomi Suzuki Naoki Sugihara Eiichi Iguchi Katsuya Teshima Shuji Oishi Masayuki Kawasaki 《Crystal Research and Technology》2007,42(12):1217-1221
The specific surface free energy of ruby and quartz single crystal was experimentally obtained using contact angle of water and formamide droplets on the crystal surfaces, and compared with the morphology of each crystal. The ruby crystals satisfied Wulff's relationship even though their shape were not equilibrium form. The specific surface free energies of the growing faces of synthetic quartz crystal, ‐X, +X, Z, and S faces were obtained as 51.9, 55.6, 57.4, and 58.9 mN/m, respectively. The growth rates of these faces were 0.09, 0.23, 0.28, and 0.33 mm/day, respectively. The growth rate of each face of the quartz crystal can be regarded as a function of the experimentally obtained specific surface free energy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
978.
Plasma-induced surface radicals formed on a variety of organic polymers have been studied by electron spin resonance (ESR), making it possible to provide a sound basis for future experimental design of polymer surface processing, i.e., plasma treatment. On the basis of the findings from such studies, several pharmaceutical applications in the field of drug engineering have been devised, which include preparation of double-compressed tablets for reservoir-type drug delivery system (DDS) of sustained- and delayed-release, and fabrication of functionalized composite powders applicable for matrix-type DDS by a mechanical application of plasma-irradiated polymer powder. 相似文献
979.
We present information criteria for statistical model evaluation problems for stochastic processes. The emphasis is put on the use of the asymptotic expansion of the distribution of an estimator based on the conditional Kullback–Leibler divergence for stochastic processes. Asymptotic properties of information criteria and their improvement are discussed. An application to a diffusion process is presented. 相似文献
980.
Jae-Dong Kim Yong-Il Park Koichi Kobayashi Masayuki Nagai Masayuki Kunimatsu 《Solid State Ionics》2001,140(3-4):313-325
The CO tolerance of a proton exchange membrane fuel cell (PEMFC) was investigated by ac impedance spectroscopy. The impedance of the fuel cell could be obtained by feeding oxygen into the cathode side and simulated gas into anode side. Furthermore, the anode impedance could be obtained by feeding hydrogen into the cathode side and simulated gas into anode side. The CO gas had a greater effect on the charge transfer reaction (high frequency arc) and hydrogen dissociative chemisorption (medium frequency arc) but little effect on the low frequency arc. Although the cathode impedance is a main part at high temperature, irrespective of CO concentration (≤100 ppm), the impedance of the full cell depends on anode impedance at low temperature and high CO concentration. It was found that CO gas has little effect on cathode impedance. 相似文献