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131.
Preparation of polyimide-epoxy composites 总被引:2,自引:0,他引:2
Kevin Gaw Mitsutoshi Kikei Masa-aki Kakimoto Yoshio Imai 《Reactive and Functional Polymers》1996,30(1-3):85-91
The formation of a three dimensional network of crosslinked epoxy leads all unmodified epoxies to have inherent brittleness and relatively low degradation temperatures. Polyimides, on the other hand, are widely used for applications that require high degrees of flexibility and thermal resistance. Here, we have focused on the preparation of epoxy systems cured with polyamic acids instead of traditional amino-group-containing hardening agents. The cure behavior and potential reaction mechanisms of EPON 828 resin and polyamic acid mixtures were evaluated by DSC and TGA. Thermal analysis showed a complex reaction sequence taking place in the mixture and also determined the extent of reaction of the polyamic acid with itself and the competitive reaction of the polyamic acid with the epoxy. The compositions of the mixtures were varied to see the dependence of the cure behavior on component concentrations. Solutions of the two components did not phase separate and also phase separation was not apparent either optically or microscopically in the cured samples. This phase behavior was attributed to a unique in situ reaction. A novel solvent system for the polyamic acid precursor was also used. 相似文献
132.
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134.
A relationship between emission characteristics of Ba atom as an emitter material and temperature distributions of an electrode in a fluorescent lamp is described, which is measured by using laser-induced fluorescence and black-body radiation method, respectively. In a virgin lamp, a hot spot observed at the electrode edge connected to the power supply is the main source of Ba atom emission. In a long-term-used lamp, it is shown that Ba atom emission, thermionic electron emission in cathode half-cycle and electron collection in anode half-cycle are most active on the hot spot appearing on the center of the electrode. 相似文献
135.
Yoshio Nishi Koreyuki Tunashima 《Journal of Infrared, Millimeter and Terahertz Waves》1987,8(11):1453-1470
In FIR laser emissions optically by a CO2 laser, it has been reported that there are two different process namely “induced Raman scattering” and “population inversion transition”. In this paper, we show that the two different process have clearly different characteristics in emission frequensies and pulse waveforms in the case of a TEA-CO2 laser excitation. We used in this work an intra-cavity etalon for the study of the emission frequensies and also we used a MOM point contact diode for the detection of the wavaformes. Especially, we show that the FIR pulse waveformes are able to analyze numerically on the concept of rate equations. In conclusion, we indicate that molecules would be classified into two categories with regard to optically pumping by a TEA-CO2 laser. One of them produce mainly Raman scattered emissions, and other produce only the FIR emissions from population inversion transition in spite of high power intensity excitation. 相似文献
136.
Yoshio Nishi 《Journal of Infrared, Millimeter and Terahertz Waves》1987,8(9):1189-1210
The author reports that TEA-CO2 with an intra-cavity etalon is a useful pumping source which can deliver widely tunable beam (tunable range ~1 GHz) with accurate oscillation frequencies and with high power compared to a tunable wave guide laser. The source is applied to the excitations of CH3OH and the FIR emissions from it are well assigned for there absorption transitions and FIR emissions. This proves that the source display not only usefulness for development of new FIR emissions but also for molecular spectroscopy. 相似文献
137.
138.
Hasegawa Tatsuro Yamauchi Hisashi Sashida Yoshio Matsumoto Mitsuo 《Industrial Electronics, IEEE Transactions on》1985,(3):253-260
Recent application of distributed control systems to large-and medium-scale industrial plants requires effective and high-speed communication among the control devices each other to ensure high-performance operation. 相似文献
139.
In this paper, the numerical analysis is given which is applicable for a TEA-CO2 laser pumping in search of effective pumping method. The analysis also can estimate the optimum pressure for a given molecule and a given pulse laser. Also we report in this work many FIR laser emissions from population inversion transition which have never observed before using a TEA-CO2 laser. 相似文献
140.
Shinichi Yamamoto Yoshio Ohashi Yuji Masubuchi Takashi Takeda Teruki Motohashi Shinichi Kikkawa 《Journal of Alloys and Compounds》2009,482(1-2):160-163
Oxynitrides in the (Nb1−xAlx)(O,N) quaternary system were prepared by ammonolysis of oxide precursor obtained through the citrate route. The products at 1000 °C were a mixture of Nb(N,O) and NbN0.95 at the niobium end (x = 0) and amorphous Al(O,N) at the aluminum end (x = 1). A new cubic compound (A) appeared mixed with Nb(N,O) in the compositional range 0.1 ≤ x ≤ 0.4. Its almost pure product was obtained at x = 0.5. The X-ray diffraction pattern was rock salt type (Nb0.56Al0.44)(O0.38N0.37□025) in Fm−3m with a = 0.43481(1) nm. The product showed superconductivity with Tc = 15 K. Its crystallinity was much improved and its superconducting volume fraction increased to 32% after its thermal annealing at 1100 °C in evacuated sealed tube. A second cubic compound (B), rock salt type Nb[(O,N)0.85□0.15] with a = 0.434 nm, was observed mixed with amorphous Al(O,N) in the as-prepared products of the range 0.6 ≤ x ≤ 0.9. 相似文献