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991.
本文介绍了一种以氟气和惰性气体为原料合成 Kr F2 和 Xe F2 的热催化合成方法并对合成机理和条件作了简单的讨论 ,利用合成的 Kr F2 作为氟化剂合成了含氟高能氧化剂 NF4BF4,纯度约为 93%,其红外光谱和拉曼光谱基本与文献值吻合。元素分析结果表明产品 NF4BF4中含 B5.8%(mass) ,自由氟原子含量为 9.95%(mass) ,与理论值基本一致 ,此结果也间接证明了 Kr F2 质量的可靠性。粉末状的 Xe F2 经升华 -再结晶纯化后可得纯净晶体产品。 相似文献
992.
993.
994.
用TEM研究了(NR SBR)/PE共混体系经动、静态硫化后的形态结构及其与力学性能的关系。未硫化和静态硫化体系的形态结构与其组成有关,均以含量大的组份为连续相;对动态硫化体系,当(NR=SBR)/PE<70/30时,均以PE为连续相,其性能主要依赖于构成连续相组份的性质。 动态硫化体系的T_g值低于静态体系,随PE组份含量的增加变化不大,而静态硫化体系的T_g值则随PE含量增加向高温方向迁移。用DSC测得动态硫化体系的结晶度比静态体系的大。前者的应力-应变性能也低于后者。 相似文献
995.
Jocelyn M. Bouzaid R. L. Frost W. N. Martens 《Journal of Thermal Analysis and Calorimetry》2007,89(2):511-519
The thermal stability and thermal decomposition pathways for synthesized composite iowaite/woodallite have been determined
using thermogravimetry analysis in conjunction with evolved gas mass spectrometry. Dehydration of the hydrotalcites occurred
over a range of 56–70°C. The first dehydroxylation step occurred at around 255°C and, with the substitution of more iron(III)
for chromium(III) this temperature increased to an upper limit of 312°C. This trend was observed throughout all decomposition
steps. The release of carbonate ions as carbon dioxide gas initialised at just above 300°C and was always accompanied by loss
of hydroxyl units as water molecules. The initial loss of the anion in this case the chloride ion was consistently observed
to occur at about 450°C with final traces evolved at 535 to 780°C depending of the Fe:Cr ratio and was detected as HCl (m/z=36). Thus for this to occur, hydroxyl units must have been retained in the structure at temperatures upwards of 750°C. Experimentally
it was found difficult to keep CO2 from reacting with the compounds and in this way the synthesized iowaite-woodallite series somewhat resembled the natural
minerals. 相似文献
996.
新试剂3,5—二溴—4—偶氮8—羟基喹啉苯基荧光酮光度法测定微量铝 总被引:9,自引:0,他引:9
在溴化十六烷基三甲胺(CTMAB)存在下,PH6,0的HAc-NaAc缓冲介质中,铝与新试剂3,5-二溴-4-偶氮8-羟基喹啉苯基荧光酮形成红色三元胶束配合物,最大吸收波长位于564nm,表观摩尔吸光系数ε为1.35×10^5.mol^-1.cm^-1,铝浓度在0~5μg/25mL范围内符合比耳定律,拟定的方法用于铝铁黄铜中微量铝的测定,结果满意。 相似文献
997.
998.
J. Goworek W. Stefaniak Agnieszka Kierys Mariola Iwan 《Journal of Thermal Analysis and Calorimetry》2007,87(1):217-222
Mesoporous silica material of MCM-41 type was synthesized by co-condensation
of highly concentrated octyltriethoxysilane (OTEOS), octadecyltriethoxysilane
(ODTEOS) and tetraethoxysilane (TEOS). The obtained hybrid materials were
characterized using XRD, TG-DSC and low temperature adsorption/desorption
of nitrogen. It was shown that the applied method of synthesis allows to obtain
silica of MCM-41 type with a high degree of hydrocarbon saturation. 相似文献
999.
Nanosized copolymer latex of hydroxypropylmethylcellulose (HPMC) grafted with ethyl acrylate (EA) and dimethylaminoethyl methacrylate
(DMAEMA) has been prepared by acidifying submicron-sized latex particles synthesized by soap-free emulsion graft copolymerization
using potassium persulfate (KPS) as initiator. The effects on the diameter of the latex particles of different conditions,
for example concentration of DMAEMA, amount of HPMC, and ratio of HCl to DMAEMA for acidification, were investigated. It was
found that increasing the mole ratio of HCl to DMAEMA to 1.0 and increasing the DMAEMA content both resulted in a decrease
in particle diameter, whereas increasing the amount of HPMC resulted in larger particle sizes. Measurement by dynamic light
scattering (DLS) revealed the diameter of the latex particles was >200 nm before acidification and <100 nm after acidification.
Evidence of grafting was obtained by use of Fourier transform infrared (FTIR) spectroscopy. Transmission electron microscopy
(TEM) was used to characterize the morphology of the copolymer particles before and after acidification. 相似文献
1000.
Two lipids with similar melting ranges but of different composition were analyzed using differential scanning calorimetry and X-ray diffraction. The lipids were processed via extrusion or were tempered at different temperatures; they were analyzed directly after extrusion and after storage at 40°C. Precirol ATO 5® showed high sensitivity to storage time and varied temperature exposure. Extrusion showed only marginal influences on the solid state. Melting peaks were narrower and shifted to higher temperatures in comparison to the untreated powder. Dynasan 114® was more robust, changes in the solid state could only be shown for samples treated above the melting range. Thus, Dynasan 114® is more appropriate for solid lipid extrusion of pharmaceutical products. 相似文献