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The ammonium chloride route to anhydrous rare-earth metal trichlorides, RECl3, is a two-step procedure consisting in, firstly, the (dry or wet) synthesis of a complex chloride, (NH4)3 RECl6 (t≈ 220°C) and, secondly, its decomposition either directly (small RE, t≈ 425°C) or via the intermediates (NH4)2 RECl5 (large RE, t≈ 385°C) and NH4RE2Cl7 (medium-size RE), respectively. 相似文献
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含苯并噁唑半芳香聚酰胺的合成与表征 总被引:2,自引:0,他引:2
为了得到同时具有优良耐热性能和易加工性能的新型半芳香聚酰胺,以5-氨基-2-(对氨基苯)苯并噁唑(ABO)和己二酸基于Yamazaki磷酸化过程合成了聚己二酰对苯撑苯并噁唑二胺(BO6).研究了反应温度对聚合物分子量的影响,并通过FTIR、1H-NMR对其结构进行了表征;利用DSC、TG对其热性能进行了研究.结果表明:反应温度在90℃左右时高聚物获得了最高的粘数.该聚合物的耐热性较脂肪族聚酰胺有较大幅度的提高,同时该聚合物具有较好的耐溶剂性能. 相似文献
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M. M. Aslzadeh G. M. M. Sadeghi M. Abdouss 《Materialwissenschaft und Werkstofftechnik》2010,41(8):682-688
Recycling of polyethylene terephthalate (PET) by aminolysis breeds environmental benefits. In this work Polyethylene terephthalate in the form of waste fibers were subjected to depolymerization through aminolysis using excess amount of ethanolamine in the presence of sodium acetate, as catalyst. Obtained product, bis (2‐hydroxy ethylene) terephthalamide (BHETA) was in its pure form with sufficiently high yields. The purified product was characterized by FTIR, 1HNMR and 13CNMR spectroscopy as well as melting point determination. Since catalyst and raw materials have low price, synthesis of this material is economical and could be used as diol to synthesis of polyurethanes. In this search, polyurethanes have been synthesized based on BHETA, HDI and polyethylene glycol via prepolymer method. Termogravimetric analysis (TGA) and Differential scanning calorimetry (DSC) were carried out to study thermal stability, thermal transitions, Tm and Tg of synthesized polyurethanes. Effect of BHETA content in the main chain of synthesized polyurethanes on thermal stability of polyurethanes, strength and stiffness has been evaluated. BHETA based polyurethanes show Young's modulus about 300 MPa and elongation at break as 130% due to its aromatic structure. 相似文献
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Khaled Hriz Nejmeddine Jaballah Jean-Louis Fave Mustapha Majdoub 《Journal of Materials Science》2012,47(23):8067-8075
Two soluble anthracene-based organic materials (BPA-An1 and BPA-An2) have been synthesized and characterized. The optical properties of these π-conjugated systems were investigated by UV–Visible absorption and photoluminescence (PL) spectroscopies. The optical gaps were estimated from the absorption onsets of the thin polymer films; their values were 3.01 and 2.76?eV for BPA-An1 and BPA-An2, respectively. The PL spectrum of BPA-An2 exhibits a blue emission both in dilute solution and thin film. BPA-An1 showed a blue photoluminescence in dilute solution; in solid film, π–π interactions influence its optical behavior and a green emission was observed. The HOMO and LUMO levels were estimated using cyclic voltammetry analysis. Single-layer devices of the (indium-tin oxide/anthracene-based material/aluminum) configuration have been elaborated and showed relatively low turn-on voltages of 6.2–5.5?V for BPA-An1 and BPA-An2, respectively. 相似文献
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《Advanced Powder Technology》2022,33(11):103776
In this study, the synthesis and formation mechanism of anhydrous magnesium carbonate (AMC) using hydrothermal method is proposed from the perspective of ionic reaction. Validation experiments were conducted, and the effect of the pH of the reaction solution and the form of carbon source on AMC preparation was investigated. It is found that HCO3? can accelerate crystal growth and reduce crystal size, and the preparation conditions of AMC can be quantified. The AMC particles were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The AMC prepared using urea as carbon source has a small particle size in the presence of ion pairs of Na+/Cl? or K+/SO42?. AMC prepared using magnesium chloride as magnesium source has smaller composition units than those prepared using magnesium sulfate as magnesium source. The effects of ions types, reaction temperature, reaction time and filling degree on the phase transition and crystal growth of AMC are also discussed. 相似文献
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以中间体(N,N,N’,N’-四丙酸甲酯-1,4-苯二胺)、1,2,2,6,6-五甲基哌啶醇为原料,在四异丙基钛酸酯为催化剂的条件下,通过酯交换反应合成了一种未见文献报道的高度对称的树枝状结构的化合物—新型防老剂(N,N,N’N’-[1,4苯二胺]-丙酸[1,2,2,6,6]-五甲基]哌啶醇酯)。产物的结构通过红外(FT-IR)、液相色谱-质谱(LC-MS)、元素分析及核磁(1 HNMR)等确定。为了研究新型防老剂的性能,实验将合成的新型防老剂、防老剂D(N-苯基-β-萘胺)、光稳定剂GW-622分别添加到天然橡胶中制成胶片,对其进行抗热氧老化性能和耐紫外光老化性能测试。结果表明合成的新型防老剂具有良好的抗热氧老化性能和耐紫外光老化性能。 相似文献
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B. Chandrakantha Arun M. Isloor Reji Philip M. Mohesh Prakash Shetty A. M. Vijesh 《Bulletin of Materials Science》2011,34(4):887-891
A new series of 1,3,4-oxadiazole derivatives containing 2-fluoro-4-methoxy phenyl were synthesized by refluxing mixture of acid hydrazide 3 with different aromatic carboxylic acids (a–e) in phosphorous oxychloride. These newly synthesized compounds were characterized by NMR, mass spectral, and IR spectral studies, and also by C, H, N analyses. The open-aperture z-scan experiment was employed to measure the optical nonlinearity of the samples at 532 nm, using 5 ns laser pulses. The measurements indicate that compound 4a, which contains Bromine, behaves as an optical limiter at this wavelength, with potential applications in optoelectronics. 相似文献
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Magnetic Fe(2)O(3) nanoparticles coated with SiO(2) chemically doped with a Ru(II) complex were prepared using a simple solution based method. Field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) showed that the Fe(2)O(3) nanoparticles with a mean diameter of ~115?nm were successfully coated with Ru(II) complex-chemically doped SiO(2) shell with a thickness of ~30?nm. The obtained nanocomposite material showed a strong magnetic response to a varying magnetic field, exhibited the bright red triplet metal-to-ligand charge transfer ((3)MLCT) emission, and its photoluminescent intensity was sensitive to oxygen concentration. Compared with the Ru(II) complex in silica gels, the Ru(II) complex in the magnetic-optical-oxygen-sensing nanocomposite demonstrated improved thermodynamic stability of emissions. These nanocomposites are also nontoxic and easily conjugated with biomolecules. Their magnetic, photoluminescent and oxygen-sensing properties make them promising candidates for cell separation, biomarkers and optical oxygen sensors, which can measure the O(2) concentration in biological bodies. 相似文献
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New polyaniline/nanotube (PANI/NT) composites have been synthesized by “in situ” polymerization processes using both multi-wall carbon nanotubes (MWNTs) and single-wall carbon nanotubes (SWNTs) in concentrations ranging from 2 to 50 wt.%. Although no structural changes are observed using MWNTs above a concentration of 20 wt.%, the in situ synthesis results in electronic interactions between nanotubes and the quinoid ring of PANI leading to enhanced electronic properties and thus to the formation of a genuine PANI/MWNT composite material. On the other hand, using SWNTs favors the formation of inhomogeneous mixtures rather than of a homogeneous composite materials, independent of the SWNT concentration. X-ray diffraction, Raman and transport measurements show the different behavior of both classes of nanotubes in PANI/NT materials. The difficulties in the formation of a true PANI/SWNT composite are related to the far more complex structure of the SWNT material itself, i.e. to the presence of entangled bundles of SWNTs, amorphous carbon and even catalytic metal particles. 相似文献
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Optically transparent nanocomposites are of special interest since they have great potential in optical applications. The synthesis of poly(methacrylic methylester)/monodispersed Cu2(OH)2CO3 particles, a new nanocomposite material with a refractive index similar to glass, is here described. The system can be easily deposited on glass plates by spin-coating technology, yielding homogeneous, low-defect thin films of high transparency, that can be used as color filters for liquid crystal displays. Differential scanning calorimetry (DSC), dynamic light scattering (DLS), scanning electron microscope (SEM), transmission electron microscope (TEM), and energy dispersive spectroscopy (EDS) have been used to characterize the composite material. 相似文献
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The preparation and characterization of pure rare-earth-metal bulks with controllable nanostructures are reported in this paper. A novel 'oxygen-free' in?situ synthesis technique that combines inert-gas condensation with spark plasma sintering (SPS) technology is proposed. Taking into account the special mechanisms of SPS consolidation and the scale effects of nanoparticles, we introduced practical procedures for preparing rare-earth bulks of amorphous, mixed amorphous and nanocrystals, and nanocrystalline microstructures, respectively. Compared with the conventional polycrystalline bulk, these nanostructured bulks exhibit substantially improved physical and mechanical properties. This technique enables comprehensive studies on the microstructures and properties of a large variety of nanostructured metallic materials that are highly reactive in the air. 相似文献
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E S ZAKARIA I M ALI M KHALIL T Y MOHAMED A EL-TANTAWY 《Bulletin of Materials Science》2016,39(7):1709-1724
With different methods, different molar ratios and different surfactants have been investigated to reach the optimum conditions for synthesized zirconium tungstate (Zr(IV)W). Zr(IV)W with different molar ratios of o-toluidine was synthesized to reach the optimum conditions for poly-o-toluidine zirconium tungstate (POTZr(IV)W). POTZr(IV)W with different molar ratios of tungstate was used to achieve the optimum conditions for poly-o-toluidine Zr(IV) tungstophosphate (POTZr(IV)WP). The Na+ capacity for all the prepared materials was investigated in order to determine the best ion exchanger towards the absorbed ions. The chemical and physical properties of materials were determined. Sorption isotherm studies of La3+, Ce3+, Nd3+ and Sm3+ ions were performed at different reaction temperatures and analysed by Langmuir, Freundlich, Dubinin–Raduchkivich and Temkin isotherm models. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were determined and found to be endothermic and spontaneous in nature. 相似文献
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Yutaka Fujimoto Takayuki Yanagida Yuui Yokota Akio Ikesue Akira Yoshikawa 《Optical Materials》2011,34(2):448-451
We investigated basic optical and scintillation properties of pure Y2O3, Tm3+-doped Y2O3, pure Lu2O3 and Nd3+-doped Lu2O3 transparent ceramics made by a sintering method. All ceramic samples showed 60–80% transparency, and some absorption bands due to Nd3+ 4f–4f transition were observed in Nd3+:Lu2O3 ceramic. Both Tm3+:Y2O3 and Nd3+:Lu2O3 ceramics showed sharp luminescence lines corresponding to the 4f–4f transition under 285 nm (Tm3+:Y2O3) and 340 nm (Nd3+:Lu2O3) excitation. The photoluminescence decay times were calculated to be about 24 μs for Tm3+:Y2O3 and 1 μs for Nd3+:Lu2O3, respectively. In radioluminescence measurements, Tm3+ and Nd3+ 4f–4f luminescence were observed for Tm3+-doped Y2O3 and Nd3+-doped Lu2O3 ceramics under 241Am 5.5 MeV α-ray excitation. Finally scintillation light yield was investigated with pulse height analysis. 相似文献
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以FePO4·xH2O为铁源与Li2CO3混合,以草酸为还原剂,在常温机械活化作用下合成出无定形态LiFePO4,然后低温热处理合成晶态的LiFePO4.考察了不同合成温度、时间对产物晶形结构、形貌和电化学性能的影响.结果表明,600℃热处理12h后制得的LiFePO4粒径细小且分布均匀,一次粒子粒径在100~200nm之间;该材料在0.1、0.2、0.5和1C下首次放电比容量分别为165、160、156和154mAh/g,50次循环后放电比容量分别为163、159.2、154.66和153.4mAh/g,容量保持率分别为98.8%、99.5%、99.1%和99.6%. 相似文献