Preparation of ordered mesoporous SiCN ceramics with large surface area and high thermal stability

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.     

新技术在液氯工序中的应用

介绍了经济器螺杆式氯气液化机组液化法和液氯液下泵输送技术的应用情况及取得的经济效益。     

管型结构对提升管流动特性的影响

采用边壁补气模拟重油催化裂化提升管反应装置中气体的膨胀行为，通过比较直管型提升管和锥型提升管中的气–固流动行为，研究了锥形提升管结构对油气膨胀所带来的流动特征变化的适应与改善. 实验结果表明，相对于直管型提升管，锥型提升管对流化气量的变化有较好的适应能力，且能有效地改善床层内的颗粒速度、空隙率的径向分布以及压力的轴向分布.     

传感器用双组分加成型硅凝胶的研究

以聚甲基乙烯基硅氧烷为基胶、含氢硅油为交联剂、氯铂酸配合物为催化剂、含乙烯基的MQ树脂为补强填料、含环氧基的硅氧烷为增粘剂 ,配制加成型双组分硅凝胶 ;研究了聚甲基乙烯基硅氧烷基胶摩尔质量、交联剂的用量、催化剂的用量、MQ树脂的用量、增粘剂的用量等对硅凝胶性能的影响。结果表明 :选用粘度为 12 0 0～ 15 0 0mPa·s的基胶 ,按基胶质量计交联剂用量为 3 5 %～ 4 0 % ,MQ树脂用量为 6 0 %～ 8 0 % ,增粘剂用量为 0 9% ,铂催化剂用量 60× 10 - 6 ,可制得外观无色透明 ,硫化时间 3～ 6h、针入度大于 10 0的硅凝胶     

小尺寸TS-1的合成及其催化油酸甲酯环氧化

为高效催化大尺寸油酸甲酯（MO）分子环氧化反应制备绿色增塑剂环氧油酸甲酯（EMO），采用水热法合成钛硅沸石（TS-1）和纯硅沸石（S-1），进一步利用水蒸气辅助晶化法成功制备了小尺寸的纳米TS-1（TS-1-s）和S-1（S-1-s）催化剂。重点考察了TS-1-s催化剂合成过程中溶胶干燥温度、溶胶与水质量配比、水蒸气晶化温度和晶化时间对其微观结构和催化油酸甲酯环氧化反应性能的影响。进一步，采用了XRD、UV-vis、SEM、TEM等手段对TS-1-s催化剂的结构进行了系统的表征。结果表明，相较于传统大晶粒TS-1催化剂（MO转化率39.20%，EMO选择性82.56%），TS-1-s催化剂表现出更优异的催化性能（MO转化率53.58%，EMO选择性85.48%）。     

填料-橡胶间的物理和化学作用Ⅲ.Al2O3,nano-Al2O3及nano-Al2O3/NDZ-101与NR

研究了Al2O3与NR的相互作用,发现二者交互作用的物理交联密度与Al2O3的吸油值和比表面积呈正相关性,与粒径和pH值呈负相关性,与吸油值(结构性)的相关性最大。Al2O3对硫化体系与NR的相互作用有屏蔽效应,使化学交联密度下降,但是与其比表面积和吸油值呈负相关性,与粒径和pH值呈正相关性。微米Al2O3无(4μm)或略有(1μm)增强作用。纳米的(25nm)有较大的增强作用,且全部是物理交联作用的贡献。加入偶联剂后,纳米Al2O3与NR的化学交联率达77.5%,化学交联对拉伸强度的贡献率达89.8%。     

插层复合技术在复合材料制备中的应用

介绍了聚合物/粘土纳米复合材料的插层方法、制备原理和工艺过程,探讨了粘土表面改性的影响因素,概述了插层复合材料的应用.     

填料对双组分缩合型室温硫化硅橡胶性能的影响

考察了多种补强填料和半补强(或增量)填料如硅藻土、碳酸钙和氧化铝等对室温硫化(RTV)硅橡胶的机械性能和介电性能的影响。结果表明,采用经六甲基二硅氮烷处理的气相法白炭黑或沉淀法白炭黑作填料时,RTV硅橡胶多方面的性能都有所提高;采用补强填料和半补强填料并用的RTV硅橡胶的性能优于使用单一补强填料的RTV硅橡胶;随着填料用量的增加,RTV硅橡胶的机械性能、相对介电常数和介质损耗因数都有一定程度的提高,但体积电阻率有所降低。     

销钉机筒挤出机内销钉附近物料流场分析及功率计算

采用当量粘度的方法，基于牛顿流体模型，提出销钉机筒挤出机内销钉附近流场的应力及速度分布数学模型和销钉消耗功率的计算方法。用NR／炭黑混炼胶进行的挤出过程中销钉消耗功率的研究结果表明，实测值与计算值的相对误差只有4％。     

Structure and properties of nitrile rubber (NBR)–clay nanocomposites by co‐coagulating NBR latex and clay aqueous suspension

Nitrile rubber (NBR)–clay nanocomposites were prepared by co‐coagulating the NBR latex and clay aqueous suspension. Transmission electron microscopy showed that the silicate layers of clay were dispersed in the NBR matrix at the nano level and had a planar orientation. X‐ray diffraction indicated that there were some nonexfoliated silicate layers in the NBR–clay nanocomposites. Stress–strain curves showed that the silicate layers generated evident reinforcement, modulus, and tensile strength of the NBR–clay nanocomposites, which were significantly improved with an increase in the amount of clay, and strain‐at‐break was higher than that of the gum NBR vulcanizate when the amount of clay was more than 5 phr. The NBR–clay nanocomposites exhibited an excellent gas barrier property; the reduction in gas permeability in the NBR–clay nanocomposites can be described by Nielsen's model. Compared with gum NBR vulcanizate, the oxygen index of the NBR–clay nanocomposites increased slightly. The feasibility of controlling rubber flammability via the nanocomposite approach needs to be evaluated further. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3855–3858, 2003