Phase behaviors of polymer solution confined between two concentric cylinders

A theoretical study on the phase behaviors of a polymer solution confined between two coaxial cylindrical walls is presented. For the case of a neutral inner cylinder, the spinodal point derived by the Gaussian fluctuation theory is confinement-independent because of the existence of a free dimension in the system. The kinetic analysis indicates that the fluctuation modes always have a component of a plane wave along the axial direction, which can lead to the formation of a periodic-like concentration pattern. On the other hand, the equilibrium structure of the system is obtained by the self-consistent mean-field theory (SCMFT) and the interplay between the “wetting” phenomenon and the phase separation is observed by modifying the property of the inner cylindrical wall. In particular, our results can be regarded as a hint to interpret the mechanism of the formation of the shish-kebab structure observed in the field of polymer crystallization.     

Perfluoroalkyl‐terminated star polymer electrolyte

A perfluoroalkyl‐terminated multiarm star polymer (perfluoroalkyl‐terminated hyperbranched polyglycerol) was synthesized and characterized on the basis of perfluorooctanoyl chloride grafting on hyperbranched polyglycerol. The conductivity of a blend of the perfluoroalkyl‐terminated star polymer and linear poly(ether urethane) was studied. The results indicated that this blend had better solvating capability in salt and higher ionic conductivity. The conductivity of the blend was 2.5 × 10^?4 S cm^?1 at 60°C when the concentration of the perfluoroalkyl‐terminated hyperbranched polyglycerol was 30 wt % and the ethylene oxide (EO)/Li ratio was 4 in the blend. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 238–242, 2005     

水在梯形截面微通道内流动阻力特性的数值研究

对梯形截面微通道内去离子水的不可压缩充分发展的流动建立数学模型,采用二维SIMPLE算法求解通道横截面上的流向速度分布.对特定几何尺寸的通道内水的充分发展流动在实验雷诺数范围内进行数值模拟,并计算充分发展段的阻力系数,将模拟所得阻力系数随雷诺数的变化关系与有关实验结果进行了对比,得到了较好的一致性.从而表明:N-S方程仍然适用于微通道内去离子水的层流流动的数值模拟.     

Nanorattle Au@PtAg encapsulated in ZIF-8 for enhancing CO2 photoreduction to CO

Nano Research - Imidazolate-based ZIF-8 catalysts M@ZIF-8 (M = Au NR, Au@Ag NR, or Au@PtAg NRT; NR = nanorod, NRT = nanorattle), were assembled. Au NRs acted as the core for the epitaxial growth of...     

The steric effect of exfoliation agent for fabrication of layer niobium oxide nanosheet

In this research, the steric effect of an exfoliation agent between n-ethylamine and triethylamine for the fabrication of Ca₂Nb₃O₁₀⁻ nanosheet was investigated. The experimental results revealed that the different structures of the exfoliation agent have affected to fabrication of Ca₂Nb₃O₁₀⁻ nanosheet. The use of n-ethylamine as an exfoliation agent gave a maximum exfoliation efficiency of 10 wt.% while the maximum exfoliation efficiency of triethylamine was 90 wt.%. The result showed that the difference in exfoliation efficiency was caused by the steric effect of exfoliation agents. The image of transmission electron microscopy exhibited Ca₂Nb₃O₁₀⁻ nanosheets which were formed by exfoliation of HCa₂Nb₃O₁₀. Furthermore, the reaction time for liquid exfoliation was studied in this work. The reaction time at 4 h gave a maximum of exfoliation efficiency. The Ca₂Nb₃O₁₀⁻ suspension was tested capability to remove hazardous ions. After the experiment, we found the white precipitate which was the formation of CsCa₂Nb₃O₁₀. The result showed that the Ca₂Nb₃O₁₀⁻ nanosheet was efficient for the removal of Cs⁺ ions in the wastewater.     

褐煤在甲烷气氛下热解特性及硫析出规律研究

利用热天平研究了龙口褐煤在甲烷气氛下的热解失重特性．研究表明,在低于400℃时,甲烷对褐煤没有促进热解的作用．在400℃～750℃范围内,甲烷促进了煤的热解．750℃以后煤在甲烷气氛下热解的TG曲线上升,出现增重．在固定床上进行了褐煤在天然气气氛下的热解实验,分析了热解气体中碳氢组分和硫的析出规律,发现煤热解气相产物中CH4（甲烷）、C2（乙烷和乙烯）、C3（丙烷和丙烯）和C4H10（丁烷）都是在350℃开始析出,到550℃达到最大值,750℃时已基本全部析出．在天然气气氛下,硫的析出量一直较在氮气气氛下多,说明甲烷能促进煤中硫向气相中迁移．     

TiO2增强聚氨酯弹性体的制备和表征

采用三步法合成了金红石型TiO2-R和锐钛矿型TiO2-A增强聚氨酯弹性体。用GPC、DSC、SEM等技术对增强聚氨酯弹性体进行了表征,并测试了其力学性能。结果表明,TiO2-R仅作为聚氨酯弹性体的硬链段成核剂;TiO2-A不仅作为硬链段成核剂,而且还参与聚氨酯的链增长反应,聚氨酯在TiO2-A表面缠绕使其在聚氨酯弹性体中分散不均匀,TiO2-A增强聚氨酯弹性体的性能低于TiO2-R。当TiO2-R在聚氨酯弹性体质量分数为4％～5％时,TiO2-R增强聚氨酯弹性体性能达到最优。     

氟硅密封剂热老化性能研究

以不同三氟丙基含量的端羟基液体氟硅橡胶作为生胶,采用共混法制备氟硅密封剂。以拉伸强度和断裂伸长率为衡量指标,采用单因素试验法探讨了三氟丙基含量、硫化剂和耐热助剂类型等对氟硅密封剂耐热老化性能的影响。结果表明,三氟丙基含量越高,氟硅密封剂的耐热老化性能越差;硫化剂类型对氟硅密封剂的耐热老化性能影响不大;耐热助剂类型对氟硅密封剂的常温力学性能影响不大,但三氧化二铁(Fe2O3)和氧化铈(CeO2)均能明显提高氟硅密封剂的耐热性能。     

铁盐催化剂在氧化法制备D-阿拉伯糖中的应用研究

研究了不同的铁盐在葡萄糖酸钙氧化制备D-阿拉伯糖的催化效果,通过高效液相检测葡萄糖酸钙的转化率和阿拉伯糖的含量,对比分析了不同铁盐的催化效果,确定了葡萄糖酸铁为葡萄糖酸钙制备D-阿拉伯糖的最佳催化剂,同时研究了葡萄糖酸铁在葡萄糖酸钙氧化降解制备阿拉伯糖最佳反应条件。为化学氧化法制备D-阿拉伯糖奠定了基础。