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71.
集化学家与化学教育家于一身的一代化学大师李比希--纪念李比希诞辰200周年 总被引:1,自引:0,他引:1
在德国著名化学家李比希诞辰200周年之际,对这位集化学家与化学教育家于一身的一代化学大师对科学和科学教育以及人类社会作出的贡献进行了评述。 相似文献
72.
In this paper, the NO-to-NO
2
conversion in various gaseous mixtures is experimentally investigated. Streamer coronas are produced with a dc-superimposed high-frequency ac power supply (10–60 kHz). According to NO
x
removal experiments in N
2
+NO
x
and N
2
+O
2
+NO
x
gaseous mixtures, it is supposed that the reverse reaction NO
2
+ONO+O
2
may not only limit NO
2
production in N
2
+NO
x
mixtures, but also increase the energy cost for NO removal. Oxygen could significantly suppress reduction reactions and enhance oxidation processes. The reduction reactions, such as N+NON
2
+O, induce negligible NO removal provided the O
2
concentration is larger than 3.6%. With adding H
2
O into the reactor, the produced NO
2
per unit removed NO can be significantly reduced due to NO
2
oxidation. NH
3
injection could also significantly decrease the produced NO
2
via NH and NH
2
- related reduction reactions. Almost 100% of NO
2
can be removed in gaseous mixtures of N
2
+O
2
+H
2
O+NO
2
with negligible NO production. 相似文献
73.
74.
75.
76.
Yong Ding Baochun Ma Qiang Gao Guixian Li Liang Yan Jishuan Suo 《Journal of molecular catalysis. A, Chemical》2005,230(1-2):121-128
The epoxidation of cyclopentene with hydrogen peroxide catalyzed by 12-heteropolyacids of molybdenum and tungsten (H3PMo12−nWnO40, n = 1–11), 12-tungstophosphoric acid and 12-molybdophosphoric acid combined with cetylpyridinium bromide as a phase transfer reagent was carried out in acetonitrile. Among 13 heteropolyacids investigated, catalyst of H3PMo6W6O40 showed the highest activity, giving a conversion of 60% and a selectivity of 95% in the epoxidation of cyclopentene. The fresh catalysts and the catalysts under reaction condition were characterized by UV–vis, FT-IR and 31P NMR spectroscopy, which has revealed that all of the molybdotungstophosphoric acids were degraded in the presence of hydrogen peroxide to form a considerable amount of phosphorus-containing species. The active species resulted from H3PMo6W6O40 are new kinds of phosphorus-containing species, which is different from {PO4[WO(O2)2]4}3−. 相似文献
77.
La2O3-Mo5Si3/MoSi2复合材料的高温氧化行为 总被引:2,自引:1,他引:2
研究了0.8%La2O3-MosSi3/MoSi2复合材料在1200℃空气中的高温氧化行为。结果表明:0.8%稀土和MoSi3的加入,使材料的抗氧化性能降低。MosSi3含量越高,材料的抗氧化性能越差。当MosSi3含量低于30%时,在氧化初始阶段,质量变化呈直线下降,随着氧化的进行,氧化逐渐增重,材料表面形成较致密的SiO2阻止了材料的进一步氧化,使得氧化增重较小。而0.8%La2O3-40%Mo5Si3/MoSi2复合材料却出现了“粉化”现象。0.8%La2O3.MosSi3/MoSi2复合材料抗氧化性能的降低,归因于Mo5Si3差的抗氧化性和材料致密度的降低;另外,稀土和Mo5Si3的加入,细化了材料的晶粒,使晶界面积增加,加速了氧在晶界中的扩散,促进了材料的氧化。 相似文献
78.
在位分散聚合聚甲基丙烯酸甲酯/二氧化硅纳米复合材料研究 总被引:70,自引:0,他引:70
应用在位分散聚合方法制备了分散相粒径介于130nm左右的聚甲基丙烯酸甲酯/二氧化硅PMMA/SiO2纳米复合材料,并利用SEM,DMA,TGA等手段研究了该体系的性能.结果表明,经表面处理的SiO2无机填料在复合材料基体中分散均匀,界面粘结好.SiO2填充粒子的用量对基体的热稳定性,动态力学行为,光学行为以及拉伸强度,弹性模量,断裂伸长率等力学性能都有较大影响 相似文献
79.
Studies on fluorenscence resonance energy transfer between CdS nanoparticles and DOCAI dyes 总被引:1,自引:0,他引:1
Lun Wang Yan Liu Hong Qi Chen A Ni Liang Fa Gong Xu 《中国化学快报》2007,18(3):369-372
The water-soluble CdS nanoparticles were synthesized in aqueous solution. A novel fluorescence resonance energy transfer (FRET) system with CdS nanoparticles as energy donors and 3,30-diethyl-oxadicarbocyanine iodide (DOCAI) dyes as energy accepter has been developed. 相似文献
80.
Preparation of flame retardant polyamide 6 composite with melamine cyanurate nanoparticles in situ formed in extrusion process 总被引:1,自引:0,他引:1
This paper is focused on in situ preparation of melamine cyanurate (MCA) nanoparticles from reaction of melamine (MEL) and cyanuric acid (CA) and their flame retardant polyamide 6 (PA6) composite in the extrusion process through a novel reactive processing method. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were utilized to characterize the in situ formed MCA nanoparticles and their blends with PA6. Introduction of pentaerythritol (LTP) and water-bound plasticizer dioctyl phthalate (DPT) into the extrusion reaction system greatly inhibits the evaporation of water required for melamine and cyanuric acid reaction at high temperature (higher than 180 °C), laying a foundation for successful in situ preparation of MCA through reactive processing. XRD and FT-IR measurements indicate that under the effect of pentaerythritol, dioctyl phthalate and water, melamine really reacts with cyanuric acid to in situ form MCA in extrusion process. The reaction degree is close to 100%. A very important finding through SEM is that the in situ formed MCA particles, which were found to have aspect ratio of about 7.5, radial size in the range of 70-300 nm (mostly 70-90 nm) and crystallite size of less than 22 nm, are uniformly dispersed in the matrix PA6 at nanoscale. The in situ formed MCA nanoparticles greatly improve the flame retardancy and the mechanical properties of flame-retarded PA6 materials, and the introduced plasticizer dioctyl phthalate also ameliorates the related impact property. The obtained flame-retarded PA6 materials have good comprehensive performance with flame retardancy UL-94 V-0 rating at 1.6 and 3.2 mm thickness, tensile strength 48.0 MPa, elongation at break 106.3% and Izod notched impact strength 8.92 kJ/m2. Compared with flame-retarded PA6 material with in situ formed MCA, the one prepared through conventional blending of PA6 with commercial MCA product has improved tensile strength but deteriorated impact strength and flame retardancy. 相似文献