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1.
Thermal degradation studies of alkyl-imidazolium salts and their application in nanocomposites 总被引:1,自引:0,他引:1
Walid H Awad Jeffrey W Gilman Marc Nyden Thomas E Sutto Paul C Trulove Douglas M Fox 《Thermochimica Acta》2004,409(1):3-11
Increasing the thermal stability of organically-modified layered silicates is one of the key points in the successful technical application of polymer-layered silicate nanocomposites on the industrial scale. To circumvent the detrimental effect of the lower thermal stability of alkyl ammonium-treated montmorillonite, a series of alkyl-imidazolium molten salts were prepared and characterized by elemental analysis, thermogravimetry (TGA) and thermal desorption mass spectroscopy (TDMS). The effect of counter ion, alkyl chain length and structural isomerism on the thermal stability of the imidazolium salts was investigated. Alkyl-imidazolium-treated montmorillonite clays were prepared by ion exchange of the imidazolium salts with Na-montmorillonite. These organically-modified clays were characterized by X-ray diffraction (XRD), TDMS and thermogravimetry coupled with Fourier transform infrared spectroscopy (TGA-FTIR), and compared to the conventional quaternary alkyl ammonium montmorillonite. Results indicate that the counter ion has an effect on the thermal stability of the imidazolium salts, and that imidazolium salts with PF6−, N(SO2CF3)2− and BF4− anions are thermally more stable than the halide salts. A relationship was observed between the chain length of the alkyl group and the thermo-oxidative stability; as the chain length increased from propyl, butyl, decyl, hexadecyl, octadecyl to eicosyl, the stability decreased. The results also show that the imidazolium-treated montmorillonite has greater thermal stability compared to the imidazolium halide. Analysis of the decomposition products by FTIR provides an insight about the decomposition products which are water, carbon dioxide and hydrocarbons. 相似文献
2.
Reactive 1,6-disubstituted perfluorohexanes have been prepared the reaction of 1,6-(dimethylhydrosilyl)-perfluorohexanes with alkyllithium and Grignard reagents. The resulting species may be derivatized in the same manner as organolithium reagents, but are appreciably more stable than the 1,6-dilithioperfluorohexane which is presumably generated by the halogen-metal exchange between an alkyllithium reagent and Br(CF2)6Br. 1,6-bis(Bromomagnesium)-perfluorohexane was also prepared in good yield by a halogen-metal exchange reaction. 相似文献
3.
The inverse addition of trichloro-2-thienyl-lithium to hexafluorobenzene in THF or ether has given 1,4-bis(trichloro-2-thienyl) tetrafluorobenzene in addition to the tetrakis(trichloro-2-thienyl)difluorobenzene. n-Butyl-lithium with hexafluorobenzene gave mono, bis tris and tetrakis compounds whereas t-BuLi afforded only 1,4-bis(t-butyl)tetrafluorobenzene in excellent yield. Other organolithium and organomagnesium reagents gave the expected products. IR, 19F NMR and UV spectral data are presented for the several new compounds. 相似文献
4.
L. I. Kravets A. B. Gilman M. Yu. Yablokov V. M. Elinson B. Mitu G. Dinescu 《Russian Journal of Electrochemistry》2013,49(7):680-692
The surface and electrochemical properties of polypropylene track membrane treated by plasma of nitrogen, air, and oxygen are studied. The effect of the plasma-forming gas composition on the surface morphology is considered. The membrane surface microrelief formed during the gas-discharge etching is found to change. Moreover, the non-polymerizing gas plasma treatment induces oxidation of the membrane surface layer and generates oxygen-containing functional groups, mostly carbonyl and carboxyl. The higher membrane roughness and its hydrophilization is shown to lead to its better wettability. In addition, the presence of polar groups in the membrane surface layer modifies its hydrodynamic and electrochemical properties so that water permeability and conductivity of modified membranes increase. 相似文献
5.
Rachek IA Barkov LM Belostotsky SL Dmitriev VF Dyug MV Gilman R Holt RJ Lazarenko BA Mishnev SI Nelyubin VV Nikolenko DM Osipov AV Potterveld DH Sadykov RSh Shestakov YV Stibunov VN Toporkov DK de Vries H Zevakov SA 《Physical review letters》2007,98(18):182303
A new accurate measurement of the tensor analyzing powers T20, T21, and T22 in deuteron photodisintegration has been performed. Wide-aperture nonmagnetic detectors allowed broad kinematic coverage in a single set up: E(gamma)=25 to 600 MeV, and theta(p)(cm)=24 degrees to 48 degrees and 70 degrees to 102 degrees . The new data provide a significant improvement over the few existing measurements. The angular dependency of the tensor asymmetries in deuteron photodisintegration is extracted for the first time. 相似文献
6.
Jiang X Arrington J Benmokhtar F Camsonne A Chen JP Choi S Chudakov E Cusanno F Deur A Dutta D Garibaldi F Gaskell D Gayou O Gilman R Glashauser C Hamilton D Hansen O Higinbotham DW Holt RJ de Jager CW Jones MK Kaufman LJ Kinney ER Kramer K Lagamba L de Leo R Lerose J Lhuillier D Lindgren R Liyanage N McCormick K Meziani ZE Michaels R Moffit B Monaghan P Nanda S Paschke KD Perdrisat CF Punjabi V Qattan IA Ransome RD Reimer PE Reitz B Saha A Schulte EC Sheyor R Slifer K Solvignon P Sulkosky V 《Physical review letters》2007,98(18):182302
We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance. 相似文献
7.
8.
Literature data on the surface modification of ultra-high-molecular-weight polyethylene as fibers and powder under the influence of low-temperature plasma are analyzed. The change in polymer chemical composition and structure is described. The results of the studies, indicating a significant improvement in the contact and adhesion characteristics of the modified polymer and composite materials, are discussed. 相似文献
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10.
The transformation from current to constituent quark basis states is discussed as it applies to relating amplitudes for photon-nucleon decays of baryon resonances. The predictions for the relative signs of pion photoproduction amplitudes through baryon resonances in the and multiplets are presented and compared with experiment. Theory and experiment are found to be completely, with the pion-nucleom decay amplitudes of resonances in the having the signs characteristic of the rather than (8, 1)?(1, 8) term in the transformation axial-vector charge. 相似文献