Journal of Physical Chemistry C, 125(22), p.11813 - 11819, 2021/06
Isothermal and constant heating thermogravimetry-differential thermal analysis (TG-DTA) and Fourier transform infrared spectrometer (FTIR) measurements have been performed for pre- and post-fired sodium hydride (NaH) in the temperature range of 500-700 K, respectively. Temperature dependence of NaH thermal decomposition rates obtained by the isothermal TGs showed an inflection point at around 620 K, which was caused by two kinds of hydrogen states (rapid diffusing and immobile hydrogen). In the FTIR spectra for the NaH and sodium (Na), the specific signals were observed at around 873.4, 1010.4, 1049.5 and 1125.7 cm, and the integrated values of FTIR signals for post-fired NaH at below 550K and at above 698 K were comparable to those for pre-fired NaH and Na, respectively. Those for post-fired NaH at 602-667 K were the intermediate values of the pre-fired NaH and Na, which denoted that the Na-Na bonds haven't grown sufficiently and the hydrogen coexisted in metallic Na. In order to predict the practical kinetics of NaH thermal decomposition reaction, we suggested the simple kinetics model which assumed two kinds of rapidly diffusing and immobile hydrogen states. The simulation results revealed the inflection point in temperature dependence of the thermal decomposition rates accordingly because the transition from immobile hydrogen to rapid diffusing hydrogen crosses over at around 620 K.
Tanaka, Tadao; Nagao, Seiya; Ogawa, Hiromichi
Analytical Sciences (CD-ROM), 17(Suppl.), p.1081 - 1084, 2002/03
Structural information of humic acid dissolving in aqueous solution has been studied by ATR-FTIR spectroscopy. Two types of humic acid fractions were prepared: one is dominated by aliphatic structure and another is dominated with aromatic structure. The functional groups of both fractions have been characterized with respect to their ATR-FTIR spectral structures (ATR spectra) measured in pH range of 2 - 10. The ATR spectra were compared with the infrared spectra of the freeze-dried humic acid fractions, which were obtained using transmission Fourier transform infrared spectroscopy with KBr pellet (KBr spectra) and using diffuse reflectance infrared Fourier transform spectroscopy (DRS spectra). In a comparison between spectra obtained from the three infrared spectroscopic methods, the major absorptions of the ATR spectra for both fractions are in well agreement with those of the KBr spectra and the DRS spectra, each other. These show that the functional groups of the humic acid dissolving in aqueous solution could characterize by using the ATR-FTIR spectroscopy.
Ishida, Yuki*; Takahashi, Tetsuo*; Okumura, Hajime*; Jikimoto, Tamotsu*; Tsuchida, Hidekazu*; Yoshikawa, Masahito; Tomioka, Yuichi*; Midorikawa, Masahiko*; Hijikata, Yasuto*; Yoshida, Sadafumi*
Materials Science Forum, 389-393, p.1013 - 1016, 2002/00
no abstracts in English
Tamada, Masao; Koshikawa, Hiroshi; Hosoi, Fumio; Suwa, Takeshi
Thin Solid Films, 315(1-2), p.40 - 43, 1998/00
no abstracts in English
Kagawa, Akio; ; ; ;
PNC TN8410 94-078, 57 Pages, 1994/07
; ; ;
PNC TN8410 94-218, 188 Pages, 1994/01
; Ouchi, Yoshifusa; ; *; *
PNC TN8410 91-241, 70 Pages, 1991/08
Radiation Physics and Chemistry, 27(6), p.447 - 453, 1986/00
no abstracts in English
Seguchi, Tadao*; Tamura, Kiyotoshi*; Kudo, Hisaaki*; Shimada, Akihiko; Sugimoto, Masaki
no journal, ,
The degradation of ethylene propylene rubber (EPR) as the cable insulation material for nuclear power plants (NPP) was studied by the accelerated thermal ageing, radiation ageing and thermal - radiation combined ageing. The oxidation of EPR proceeded with both thermal and radiation and the decay of mechanical property was closely related to the degree of oxidation. The thermal oxidation was much affected by the content of antioxidant in EPR as a stabilizer, that is, the oxidation rate was almost same above a critical content of antioxidant but increased much by the decay less than the critical value. On the other hand, the radiation oxidation rate was scarcely affected by the content of antioxidant. As the antioxidant in EPR evaporates from the material surface during thermal ageing and decomposes with dose by the radiation ageing, so the oxidation distribution in the depth of EPR sheet specimen was changed with reflecting the content of antioxidant above or less than the critical value. In the case of combined oxidation of thermal and radiation ageing, the yield and distribution of oxidation in EPR specimen were different by the sequence of ageing combination. The mechanical properties were well reflected by the yield and distribution of oxidation products. As far as the antioxidant content was held above the critical value, the degradation was almost same among the sequence of thermal and radiation ageing, but when the antioxidant was decayed less than the critical value the degradation was much increased in the reverse sequential ageing. For the qualification testing method of the NPP cables, the reverse sequential combination, radiation then thermal ageing, could be recommended.