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21.
Ji-Guang LiTakayasu Ikegami Yarong WangToshiyuki Mori 《Journal of solid state chemistry》2002,168(1):52-59
A novel carbonate (co)precipitation method, employing nitrates as the starting salts and ammonium carbonate as the precipitant, has been used to synthesize nanocrystalline CeO2 and Ce1−xYxO2−x/2 (x≤0.35) solid-solutions. The resultant powders are characterized by elemental analysis, differential thermal analysis/thermogravimetry (DTA/TG), X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) analysis, and high-resolution scanning electron microscopy (HRSEM). Due to the direct formation of carbonate solid-solutions during precipitation, Ce1−xYxO2−x/2 solid-solution oxides are formed directly during calcination at a very low temperature of ∼300°C for 2 h. The thus-produced oxide nanopowders are essentially non-agglomerated, as revealed by BET in conjunction with XRD analysis. The solubility of YO1.5 in CeO2 is determined via XRD to be somewhere in the range from 27 to 35 mol%, from which a Y2O3-related type-C phase appears in the final product. Y3+-doping promotes the formation of spherical nanoparticles, retards thermal decomposition of the precursors, and suppresses significantly crystallite coarsening of the oxides during calcination. The activation energy for crystallite coarsening increases gradually from 68.7 kJ mol−1 for pure CeO2 to 138.6 kJ mol−1 for CeO2 doped with 35 mol% YO1.5. The dopant effects on crystallite coarsening is elaborated from the view point of solid-state chemistry. 相似文献
22.
William J. Orts Geoffrey A. R. Nobes Gregory M. Glenn Gregory M. Gray Syed Imam Bor‐Sen Chiou 《先进技术聚合物》2007,18(8):629-635
Blends of thermoplastic starch with poly(ethylene‐co‐vinyl alcohol) copolymer (EVOH) were melt extruded with water/glycerol as plasticizer and a series of amino acid additives. The biggest factor in end‐use mechanical properties proved to be the relative humidity (RH) during storage. Plasticized starch‐EVOH blends stored at 0 and 50% RH changed significantly over time, with, for example, the tensile strength (TS) of the glycerol‐plasticized blend increasing from 4.7 to 26.3 MPa over 8 weeks when maintained at 0% RH. In contrast, the TS of this same sample stored at 75% RH remained unchanged for 8 weeks. Amino acids provided relatively minor, but significant changes in mechanical properties with time. Based on TS, elongation‐to‐break, and modulus, it may be concluded that β‐alanine, sarcosine, and L ‐proline were more effective than glycerol at maintaining strong flexible blends. Increases in crystallinity and changes in morphology with time, as described by modulated DSC were correlated to these changes in mechanical properties. Published in 2007 by John Wiley & Sons, Ltd. 相似文献
23.
甲基丙烯酸八氟戊酯乙烯基咪唑共聚物的合成及与钴卟啉复合物的氧结合性能 总被引:3,自引:0,他引:3
研究了甲基丙烯酸八氟戊酯单体及其与乙烯基咪唑共聚物的合成与表征 ,以及该共聚物与氧载体钴卟啉配位复合物的氧结合性能 .共聚物分子量和乙烯基咪唑含量分别由GPC和元素分析方法测定 ,结果为5 0× 10 4 和 2 5mol % .共聚物中的咪唑基与钴卟啉在溶液中配位 ,复合物具有快速、可逆的氧结合特性 .溶剂对复合物的氧结合性能影响较大 ,复合物在四氢呋喃中的氧结合亲合力大于在N ,N 二甲基甲酰胺中的亲合力 相似文献
24.
A simple, quick and novel method for the determination of diffusion properties through polymer films, based on Quantum Resistive Sensors made of Conductive Polymer nanoComposites is presented. The integral time lag method is employed for the calculation of diffusion coefficient, and the results are compared simultaneously with that of Fourier transform infrared spectroscopy and sorption method. Two model polymers, a semi‐crystalline poly(lactic acid) and an amorphous poly(isobutylene‐co‐isoprene), are used to validate the study. A good correlation is established between the diffusion coefficient values derived from all techniques demonstrating the interest of such reliable, simple and cheap nanosensors for the quick determination (several minutes) of diffusion properties in polymer films. Our first results suggest that this technique is meaningful for the determination of barrier properties in nanocomposite membranes filled with platelets of graphene or clay. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
25.
Robert w. Lenz 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6):945-959
Alkyl α-chloroacrylates and p-substituted α-methylstyrenes were investigated for the effect of polymerization conditions on tacticity, molecular weight, and distribution, and for the relationship between tacticity, glass temperature, and crystalline properties. 相似文献
26.
27.
Mahsa Kiani Mojtaba Bagherzadeh Soraia Meghdadi Farzaneh Fadaei-Tirani Maryam Babaie Kurt Schenk-Joß 《应用有机金属化学》2020,34(11):e5911
The new Co(II) - carboxamide complex ( 1 ) and Co3O4 nanoparticles ( 2 ), by way of thermal decomposition of ( 1 ) have been efficiently synthesised in the environment-friendly. X-ray diffraction reveals a slightly distorted octahedral coordination of cobalt (four nitrogens and two oxygens) in ( 1 ) and regular octahedral or tetrahedral ones (oxygens only) in ( 2 ). The investigation of ( 1 ) and ( 2 ) in the Mizoroki-Heck and epoxidation of alkens reactions showed them both to be powerful, green and inexpensive catalysts. 相似文献
28.
Dr. Dhanaji V. Jawale Dr. Edmond Gravel Dr. Nimesh Shah Dr. Vincent Dauvois Prof. Dr. Haiyan Li Prof. Dr. Irishi N. N. Namboothiri Dr. Eric Doris 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7039-7042
Rhodium nanoparticles were anchored on carbon nanotubes and the resulting nanohybrid was studied as co‐catalyst, along with tert‐butylcatechol, for the dehydrogenation of various N‐heterocycles. The co‐catalytic system operates in high yields, under the mildest conditions reported so far, and can be applied to a wide variety of secondary amine‐containing scaffolds. 相似文献
29.
《Journal of polymer science. Part A, Polymer chemistry》2018,56(11):1133-1139
A modular and facile route has been developed to synthesize functionalized 2,5‐di(thiophen‐2‐yl)‐1‐H‐arylpyrroles from readily available starting materials. These units are compatible with various polymerization conditions and are versatile building blocks for conjugated polymers. The polymers show high thermal stability and solubility in a number of solvents. Characterization of the polymers reveals a correlation between molecular packing, controllable by polymer design, and charge carrier mobility. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1133–1139 相似文献
30.
Lulu Wang Jinmiao Wang Chuanbin Fan Caifeng Bi Xia Zhang Dongmei Zhang Mei Wang Yuhua Fan 《应用有机金属化学》2020,34(9):e5767
Two novel Co (II)- coordination polymers (CPs) based on 2,5-bis(4-carboxylpheny)-1,3,4-oxadiazole (bcpo), namely [Co/(bcpo)0.5(tib)(H2O)2]n (1) and [Co (bcpo)0.5(bidpe)(H2O)2]n (2) (tib = 1,3,5-tirs(1-imidazolyl)benzene, bidpe = 4,4′-bis (imidazolyl)diphenyl ether) have been synthesized under solvothermal conditions and characterized by powder X-ray diffraction (PXRD), single crystal X-ray diffraction, photochemistry as well as electrochemistry. The investigation of the photo-degradation methyl blue and methyl violet (MB, MV) properties of CPs 1–2 demonstrates that CP 1 shows great performance for the degradation of MB, and CP 2 could efficiently degrade MB/MV. Meanwhile, the possible photo-degradation mechanism has been proposed and explored. Simultaneously, electrochemistry studies show that both CPs 1 and 2 can catalyze water oxidation under an alkaline condition at the potential around 1.20 V vs. NHE with relatively low overpotential of 330–510 mV vs. NHE. 相似文献