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121.
Skuban S. J. Skuban F. Lukić S. R. Cvejić ž 《Journal of Thermal Analysis and Calorimetry》2003,71(2):439-444
The object of the paper is an investigation of the glasses of the (As2S3)x(AsSe0.5Te0.5I)100-x. type for 65≤;x≤;95, using methods of thermomechanical analysis. Values of the thermal coefficients of linear expansion in solid and visco-plastic
phase were determined. it was shown that introducing arsenic-sulfide in glass-matrix AsChI, i.e. (AsSe0.5Te0.5I), leads to an increasing stability of these glasses. The characteristic temperatures of softening Tg and the temperature of the beginning of deformation tw increase by increasing content of As2S3. The analytical forms of dependence of four significant physical values αg, αl, Tg, Tw, as a function of As2S3 content in the structure of glasses were fitted.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
122.
The solid diffusion coefficient of lithium-ion in LiCoO2 cathode material has been investigated by the capacity intermittent titration technique (CITT) at different voltages and at different charge/discharge cycles. By SEM, XRD and FTIR techniques, the structure of LiCoO2 was studied before and after charge-discharge cycles, and the relationship between solid diffusion coefficient and crystal structure was further discussed. CITT results show that the value of Li+ solid diffusion coefficient of LiCoO2 is about 10-12 cm2·s-1. During the whole charge-discharge cycles, the Li+ solid diffusion coefficient decreased within the voltage of 4.0~4.3 V, which is attributed to the change of the structure of LiCoO2. 相似文献
123.
125.
本工作建立了室温下用凝胶色谱法(GPC)测定聚2,6-二甲基苯醚(PPO)树脂分子量、分子量分布的方法。淋洗剂不采用文献申报道的毒性较大者,也不在较高柱温下进行,而采用甲苯(或氯仿)在室温下测定。对样品在甲苯中溶解温度、浓度和稳定性等都进行了系统研究,找到了最优化条件。GPC数据结合改性PPO(MPPO)产品性能测定结果,经仔细分析找到了影响MPPO产品质量的一个重要因素是PPO树脂中低分子量部分含量。它与产品冲击强度有明显的依赖关系。提出了一个从CPC谱图确定低分子量部分含量的方法。 相似文献
126.
The freezing temperatures and densities (at 31°C) of solutions of octane, nonane, decane, 3,3-diethylpentane, and sodium oleate inN-methylacetamide (NMA) have been measured. The molality of the freezing solution was calculated from the density. The solubilities of octane, nonane, and decane inN-methylacetamide are also reported. Apparent molal volumes calculated from the densities are close to the values in the pure hydrocarbons and are not strong functions of the concentration. This indicates the absence of any unusual packing effect. The calculated free energies of transfer of the hydrocarbons from pure hydrocarbon to NMA solution are much less negative than the corresponding values for water, showing that the bulk solvophobic interaction inN-methylacetamide is smaller than in water. This is consistent with the freezing temperatures of sodium oleate which show that micelles do not form below 0.1 mole-kg–1. The osmotic coefficients of the hydrocarbons calculated from the freezing temperatures showed negative deviations from ideality that were larger for the hydrocarbons with the higher molecular weights. Two estimates of the pairwise solvophobic interaction inN-methylacetamide indicate that it is also smaller than in water. The solvophobic effect in this solvent does not include the large entropy and enthalpy effects found in aqueous solutions. 相似文献
127.
Thomas C. Amu 《Journal of solution chemistry》1981,10(1):69-78
Interdiffusion coefficient have been measured for 1,1,2,2-tetrabromoethane in 21 organic solvents in order to ascertain the influence of shape, size, viscosity, nature and degree of branching, of the solvent molecules on transport properties. None of the existing correlations for diffusion in binary liquid systems appear to fit all the experimental data. Steric effects due to the solvent molecules are shown to be very important in the interpretation of the diffusion process. 相似文献
128.
Medical grade PVC plasticised with polycaprolactone–polycarbonate (PCL–PC) was subjected to aqueous environments at different temperatures. The release profile during ageing was determined by solid phase microextraction (SPME) and GC–MS. At the same time changes in the surface composition due to, for example, migration of PCL–PC from the blend were followed by FTIR. Almost no changes in the material or its surface composition were observed during 98 days at 37 °C in water or phosphate buffer. Only trace amount of 6-hydroxyhexanoic acid the final hydrolysis product of PCL–PC was detected in the GC–MS chromatograms and the weight loss was negligible. Even when the ageing temperature was raised to 70 °C only minor increase in the amount of 6-hydroxyhexanoic acid was observed and the weight loss after 98 days was under 1%. Changes in the FTIR spectra indicating migration of PCL–PC towards the surface of the PVC/PCL–PC tubing were observed first after 70 days at 70 °C. Large increase in the hydrolysis rate of PCL–PC and almost complete depletion of PCL–PC from the blend was observed when the ageing temperature was raised to 100 °C. 相似文献
129.
Summary The concept of a diffusion-averaged molecular weight, Md is presented, and Md is defined for polydisperse samples. It is shown via oligostyrene mixtures that Md can be determined in 20 minutes with common chromatographic equipment. If Md is measured and Mn or Mw is known, the polydispersity can be obtained. 相似文献
130.