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101.
Shinichi Yano Kenji Tadano Koichiro Aoki Naokazu Koizumi 《Journal of Polymer Science.Polymer Physics》1974,12(9):1875-1887
Dielectric properties of poly(vinylidene fluoride) have been studied in the frequency range 20 Hz to 1 MHz and between 100 and 220°C, during heating and cooling. The dielectric constant and loss change abruptly at the temperature Tm corresponding to the melting point. At lower frequencies, two types of ionic conductin are observed. One appears below Tm and is attributed to interfacial polarization. The other occurs above Tm and is related to electrode polarization. These results suggest that a crystalline polymer is a heterogeneous medium for ionic transport, while the melt is a homogeneous medium. From these results, the nature of ac ionic conduction in crystalline polymers is discussed. At high frequency, the α relaxation is observed below Tm. It is due to the molecular motion in the crystalline region and disappears at Tm. 相似文献
102.
Koichiro Fukuda Akira Moriyama Tomoyuki Iwata 《Journal of solid state chemistry》2005,178(6):2144-2151
The crystal structure of BaZr(PO4)2 at 298 K was determined from conventional X-ray powder diffraction data using direct methods, and it was further refined by the Rietveld method. The structure was monoclinic (space group C2/m, Z=2) with , , , β=93.086(1)° and . Final reliability indices were Rwp=8.21%, Rp=5.64% and RB=2.92%. The atom arrangement is similar to that of yavapaiite (KFe(SO4)2), however, these crystal structures differ distinctly in the coordination numbers of barium and potassium atoms; the former is tenfold coordinated, whereas the latter is sixfold coordinated. The powder specimens were also examined by high-temperature XRD and DTA to reveal the occurrence of a phase transition from monoclinic to orthorhombic at 732 K during heating. Upon cooling the reverse transition occurred at 710 K. The monoclinic crystal expanded almost one-dimensionally along [503] during the heating process. The orthorhombic phase also showed a tendency to expand one-dimensionally along the c-axis above 732 K. 相似文献
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109.
Shigeru Yabumoto Kiyoshi Ishii Masakiyo Kawamori Koichiro Arita Hiroshi Yano 《Journal of polymer science. Part A, Polymer chemistry》1969,7(7):1683-1696
The properties of the acrylonitrile–styrene copolymer prepared in the presence of zinc chloride were investigated in comparison with those of a copolymer having the same overall composition and prepared by the ordinary radical procedure. The characteristics of the polymer prepared with ZnCl2 were as follows: (1) less coloration by alkali treatment, (2) less coloration by thermal treatment and (3) higher glass transition temperature. These features may be attributed principally to the structure of the copolymer, which has more unlike bonds and less long sequences as described in the first article of this series. The effects of residual salt in the copolymer on the properties were also investigated. 相似文献