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71.
T. Yasuda T. Okuno M. Miyama H. Yasuda 《Journal of polymer science. Part A, Polymer chemistry》1994,32(10):1829-1837
Plasma treatment of a polymeric surface could involve at least three major mechanisms: (1) direct interaction of reactive species in the low-temperature plasma state with the surface (line of sight irradiation effect), and (2) chemical reactions of plasma-induced reactive species with the surface, and (3) reactions among reactive species and the surface (plasma polymerization). The first and the third effects are considered to be limited to the surfaces which directly contact with plasma (glow). The second effect is not limited to the surfaces that contact with plasma state but can penetrate beyond the plasma zone by diffusion. Using an assembly of fibers, of which only the top layer contacts with plasma (glow), the penetration of chemical changes caused by plasma exposure was investigated. Results indicate that the fluorination effect (incorporation of fluorine-containing moieties on the surface of polymeric substrate) penetrates through a considerable thickness of the assembly of fibers, depending on the porosity (gas permeability) of the system. Chemical reactions of plasma-induced (chemically) reactive but nonpolymerizing species with the substrate fibers seems to predominate. The direct interactions of energetic species, such as ions, electrons, and electronically excited species, with polymeric surfaces seems to play relatively minor roles in the plasma treatment investigated. The major role of plasma, in this case, seems to be creating such chemically reactive species. © 1994 John Wiley & Sons, Inc. 相似文献
72.
The decomposition of N2O in a 13.56-MHz parallel-plate system was studied usingin situ Fourier transform infrared (FTIR) spectroscopy. Areas of two infrared absorption bands of N2O recorded at 8 cm–1 resolution were used to estimate relative gas-phase dissociation as a function of rf power and flow rate at 500 mT. Flow rate was found to strongly affect band areas over the range of powers investigated (10–90 W). The effect of rf power on band areas diminished above 40 W, probably due to poor plasma confinement. Distortion of the band shapes by the plasma permitted rotational temperatures to be estimated. Rotational temperature increased essentially linearly with power at constant flow rate, reaching 450 K at 80 W, but was independent of flow rate at constant power. Rotational temperatures were also found to depend on the temperature of the electrodes, which were heated by plasma exposure. No infrared-active product species were observed even under batch conditions where all N2O was irreversibly dissociated. This lack of detectable products and a 50% pressure rise observed in a batch study suggest that N2 and O2 are the primary stable discharge products. 相似文献
73.
Direct Synthesis of Oxygenates from Water and Methane via Dielectric-barrier Discharge 总被引:1,自引:0,他引:1
BaoWeiWANG GenHuiXU 《中国化学快报》2004,15(7):779-780
In this investigation, a clean, atomic economic and direct synthesis of oxygenates (methanol, ethanol) form water and methane via dielectric-barrier discharge was developed at room temperature and under atmospheric pressure. The effect of discharge voltage on this process was studied. The results showed that the conversion of water can be as high as 7%, the selectivity of methanol and ethanol can be as high as 100%. 相似文献
74.
Glow discharge mass spectrometry 总被引:5,自引:0,他引:5
Hoffmann V Kasik M Robinson PK Venzago C 《Analytical and bioanalytical chemistry》2005,381(1):173-188
Over the past twenty years or so, glow discharge mass spectrometry (GDMS) has become the industry standard for the analysis of trace elements in metals and semiconductors. A review of its history is followed by a picture of the present situation and a look to where the future may lie. Applications are summarised, including the ability of GDMS to offer depth-resolved data and non-conductor analysis, and the well-documented quantitative nature of the results is reviewed. The effects resulting from the physical properties of the analyte material are discussed at length. Finally, recent work such as fast flow sources and pulsed glow discharges is reviewed. 相似文献
75.
Xudong?Hu Gui-Bing?Zhao S.?V.?B.?Janardhan Garikipati Kim?Nicholas Stanislaw?F.?Legowski Maciej?RadoszEmail author 《Plasma Chemistry and Plasma Processing》2005,25(4):351-370
Laser-induced fluorescence (LIF) is an effective in-situ probe for NO concentrations below 300 ppm in a non-thermal plasma reactor. A new method has been developed to measure in-situ NO concentration in the reactor discharge region using a long-time—on the order of seconds—averaged fluorescence detection. This method, for quantifying NO concentration in a nonthermal plasma reactor, is simpler than a short-time—on the order of nanoseconds—fluorescence detection. For accurate measurement based on the new method, the LIF intensity must be close to the corona-induced fluorescence (CIF) intensity; the CIF intensity serves as a guide in selecting the LIF intensity. We find that a kinetic model proposed earlier works for two-tube reactors and represents the NO concentration in the middle of the reactor, which verifies the assumption of gas plug flow. 相似文献
76.
Zh. Bo J. H. Yan X. D. Li Y. Chi K. F. Cen B. G. Chéron 《Plasma Chemistry and Plasma Processing》2007,27(5):546-558
The combined effects of oxygen and water vapor on three typical volatile organic compounds, i.e. tetrachloromethane, n-butane and toluene, decomposition efficiency under gliding arc gas discharge conditions are studied. The electron density
and the density of the reactive radicals such as O and OH are modified by addition of oxygen and water vapor. Consequently,
the decomposition process can be enhanced or suppressed, depending on the involved chemical structures and reaction channels.
The addition of oxygen and water vapor suppresses the tetrachloromethane decomposition which indicates that this process is
mainly controlled by the electron dissociation reactions. By contrast, the n-butane and toluene decompositions are enhanced, which shows that they can be mainly ascribed to the radical induced reactions.
Especially, in a moist atmosphere the OH radicals are supposed to play the most important role in the n-butane decomposition process. 相似文献
77.
晶态氮化碳薄膜的低温合成 总被引:1,自引:0,他引:1
The synthesis of carbon nitride films at low temperature has been investigated using pulsed arc discharge from methanol solution with nitrogen atmosphere. Raman spectra and X-ray diffraction (XRD) analysis suggest that crystalline carbon nitride films may be prepared at low substrate temperature (220 ℃). At same time, the substrate temperature has a significantly effect on the nitrogen content and structure of the films. Increasing substrate temperature (300 ℃) would decrease the content of nitrogen in the films and result in a formation of carbon films. 相似文献
78.
锂离子电池负极合金CoSn和Cu-Sn的制备与表征 总被引:9,自引:0,他引:9
CoSn alloy and Cu-Sn samples were synthesized by H2-reduction following solid-state reaction between Co(Ⅱ), Cu(Ⅱ), Sn(Ⅳ) and NaOH at ambient temperature. The samples were characterized by XRD, SEM. The results showed that CoSn alloy (80~200nm) is globe-shaped, ultrafine hexagonal material, and Cu-Sn alloy powder consists of two phases, i.e. Cu6Sn5 and Cu3Sn. Cu-Sn powder has spherical morphology and the particle size is estimated to be 60~70nm. The electrochemical performances of CoSn alloy and Cu-Sn powder were studied using lithium-ions model cell Li/LiPF6 (EC+DMC)/CoSn (or Cu-Sn). It was demonstrated the reversible discharge capacities for 10 cycles keep above 280mAh·g-1 for nanophase Cu-Sn, and 60mAh·g-1 for CoSn alloy. Differ-ential capacity plots showed that the reaction mechanisms of Cu-Sn with lithium were reversible. 相似文献
79.
The gas–liquid gliding arc discharge plasma is used directly to study degradation and dechlorination of 4-Chlorophenol (4-CP)
in solution. The typical AC waveforms of discharge voltage and current revealed that the discharge behavior was not definitely
periodic. The chemical oxygen demand (COD) abatement of 4-CP solution with stainless steel electrode is higher than that with
aluminum or brass electrode; When air was used as carrier gas the COD abated from 1,679.2 to 190 mg/L (i.e., 88.68% abatement)
after 76 min plasma treatment; Increasing gas–liquid mixing rate could also increase the degradation of 4-CP; adding appropriate
amounts of Fe2+ or iron chips to the solution were found to be favorable for 4-CP degradation. The main intermediates of 4-CP degradation
are p-benzoquinone, hydroquinone, 4-chlorocatechol, p-chloronitrobenzene, and ring cleavage products (acetic acid, glycol,
propanone, and others). Furthermore, possible pathways of 4-CP degradation in solution are proposed. 相似文献
80.