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991.
992.
For the first time, highly ordered two-dimensional (2-D) and three-dimensional (3-D) mesoporous SiCN ceramics with high surface area and high thermal stability were prepared by nanocasting a preceramic polymer solution into mesoporous carbon templates, CMK-3 and CMK-8, respectively. As a negative replica of CMK-3 carbon, the obtained mesoporous SiCN ceramic possessed an ordered 2-D hexagonal mesostructure, which is similar to the structure of SBA-15 silica except for the reduced dimensions. An ordered 3-D cubic mesoporous SiCN ceramic was also fabricated using CMK-8 as a template. The wall of the mesoporous SiCN replicas consisted of an amorphous SiCN ceramic phase, which possessed high thermal stability at high temperature up to 1000 °C. N2-sorption isotherms revealed that these ordered mesoporous SiCN ceramics have high BET surface areas (up to 472 m2 g−1) and narrow pore-size distributions, which was preserved even after a re-treatment at 1000 °C in air. The use of carbon template played an important role in the preparation of mesoporous SiCN replicas and enhanced the thermal stability of the SiCN products. It is expected that many other types of ordered mesoporous ceramics can be prepared from nanoporous carbon by nanocasting method. 相似文献
993.
Narrowly distributed nanoparticles of poly (n‐butyl methacrylate‐co‐vinyl pyrrolidone) were prepared through microemulsion polymerization with a nonionic surfactant of Tween‐80 as emulsifier (6 wt % of the latex) and n‐butanol as coemulsifier. The polymerizations were initiated with benzoylperoxide (BPO), potassium persulfate (KPS), KPS/ferric sulfate (FeSO4), and BPO/FeSO4, respectively, where the initiation in the case of BPO/FeSO4 took place mainly at the interphase between the oil phase and the reaction media. Namely, this interfacial‐initiated microemulsion polymerization resulted in larger particles with relatively narrower particle size distribution as well as higher limiting monomer conversion but lower polymerization rate compared with the polymerization initiated with KPS/FeSO4. In this article, the influences of initiation method, monomer ratio, and addition of water‐soluble components on microemulsion polymerization and latex particle size were studied to discuss the mechanism of interfacial‐initiated microemulsion polymerization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2334–2340, 2004 相似文献
994.
995.
Polyolefins (PO) were melt mixed with thermoplastic polyurethane (TPU) in a 20 : 80 weight ratio with or without compatibilizer containing 0.5 wt % of maleic anhydride. Effects of component viscosities on morphology and on mechanical properties of the blend were studied by scanning electron microscope (SEM), tensile property analysis, and dynamic mechanical analysis (DMA). It was found that the disperse particle size of compatibilizer‐free blends decreased with the decreasing viscosity ratio of the disperse phase to TPU. The efficiency of the compatibilizer in reducing the particle size varied with viscosity ratios of the disperse phase to compatibilizer. However, the particle size did not decrease with the decreasing viscosity ratio monotonically. With lower viscosity ratio, addition of 5 wt % compatibilizer resulted in a greater reduction of particle size and less loss in the tensile properties as compared to the TPU matrix. For the polyethene (PE) that has the lowest viscosity value among all the POs, its size in the blend was stabilized with the addition of compatibilizer and no compatibilization was detected by DMA and by tensile property analysis. The mobility of the disperse phase and compatibilizer and the dispersion competition between them seemed important. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 875–883, 2006 相似文献
996.
997.
根据氨-水混合物的物性,讨论了不同热源温度下Kalina循环适用的工质参数匹配,以5 000 t/d新型干法水泥生产线为研究对象,将Kalina循环系统用于水泥窑余热发电.通过系统的流程仿真模拟,得出了Kalina循环在给定废热条件下的做功能力及系统热力学性能.计算结果表明,Kalina循环系统比Rank ine循环系统发电功率提高20.4%,热效率绝对值提高2.66%,效率达到44.31%. 相似文献
998.
高温超导薄膜生长是研究超导现象和超导器件的基础,一直是凝聚态物理研究的一个重要课题。各种各样的薄膜生长方法都被应用于高温超导薄膜的生长研究。采用一种崭新的薄膜沉积设备——脉冲电子束沉积系统(PED)成功制备出了NCCO、LSCO高温超导薄膜,并通过优化沉积参数,获得了具有良好表面形貌和超导转变特性的高温超导薄膜。 相似文献
999.
根据工程实际出发,建立离散变量结构拓扑优化模型。针对基本遗传算法(GA)存在的早熟收敛、随机性大、收敛速度慢等不足,从编码方式及遗传算子操作等几个方面对其作了改进,选择操作中引进斐波那契方法,提出一种基于整数编码的改进遗传算法。优化结果表明,这种改进的遗传算法的收敛性得到了很好的改善,提高了计算效率,是有效的结构拓扑优化设计方法。 相似文献
1000.
刘燕 《重庆科技学院学报(社会科学版)》2010,(12):111-112
2004年诺贝尔文学奖得主奥地利女作家耶利内克在其自传体小说<钢琴教师>中颠覆传统观念而把母亲塑造成为一个扭曲变态的人物,我们通过对这个已成为男性缺失下的父权代言的女性形象分析可以看出一直以强烈女性意识为写作立场的耶利内克已经把女性立场的视角转化为了一种内在的,对自我的不断询问、审视和否定. 相似文献