聚乙烯载体催化剂的制备与表征

不同目数的聚乙烯粉末通过辐射方法接枝了4-乙烯基吡啶官能团.经甲基铝氧烷(MAO)预处理后负载了茂金属催化剂Cp₂ZrCl₂.光电子能谱和红外光谱结果表明催化剂通过MAO的作用负载在聚乙烯接枝4-乙烯基吡啶聚合物上.4-乙烯基吡啶的接枝含量、催化剂的负载率以及载体催化剂对乙烯单体的活性均随着聚乙烯粉末的颗粒减小而增大.     

由邻苯二胺合成苯并咪唑、喹喔啉以及1-H-2,3－二氢1,5-苯并氮杂卓

A series of benzo-fused heteroaromatic compounds with 5-, 6- and 7-membered tings, such as benzimidazole,quinoxaline and 1H-1,5-benzodiazepine derivatives, were synthesized through condensation reaction of o-pheny1-enediamine with ary1 aldehydes or ketones. The experimental conditions were carefully examined, and the products were characterized by ^1H NMR, ^13C NMR, MS, IR and elemental analyses. In addition, the structure of a benzodiazaepine derivative with 7-membered ring was confirmed by single crystal X-ray diffraction analysis.     

PREPARATION OF NOVEL POLYETHYLENE-graft-POLY(4-VINYLPYRIDINE)-SUPPORTED METALLOCENE CATALYSTS FOR ETHYLENE POLYMERIZATION

Polyethylene (PE) grafting 4-vinylpyridine copolymers has been produced as powders of different rushes by theirradiation method. After treatment with methylaluminoxane (MAO), the copolymers were used as supports for Cp_2ZrCl_2catalyst Results of X-ray photoelectron spectroscopy, Fourier transforms infrared spectroscopy, ultraviolet spectroscopy andscanning electron microscope measurements show that the catalytic sites have been linked through MAO on the PE-graft-4-vinylpyridine (PEVP). The percentages of grafting 4-vinylpyridine and supported Cp_2ZrCl_2 depend on the size ofpolyethylene powder. The smaller the polyethylene powder, the more percent of 4-vinylpyridine groups and Cp_2ZrCl_2 existon the polyethylene chains, and the PEVP-supported catalyst has a relatively high activity for ethylene polymerization.     

钛配合物烯烃聚合催化剂研究的新进展

线性低密度聚乙烯是聚烯烃材料中亟待发展的高附加值树脂，近年来获得了快速发展和产业化应用，其关键推动力在于钛配合物催化剂的研究发展。本文综述了近几年钛配合物催化剂研究的新进展，探讨了配合物结构变化对催化剂活性和共聚性能的影响规律。     

呼吸尘埃中游离晶态α—石英的X射线衍射外标法测定

本实验用Ｘ射线衍射外标法测定了极微量（０．１～５ｍｇ）呼吸尘埃中游离晶态α－ＳｉＯ２的含量，其精确度（相对偏差）小于１０％，达到常规微量（５～１０ｍｇ）样品的分析精确度。     

一维非线性弹性力学方程组的Riemann问题

本文研究了一维非线性弹性力学方程组的Riemann问题.根据左右状态所处的相对位置,分情况构造了问题的唯一整体解.由于激波条件退化,系统的基本波除了稀疏波和激波还包含退化激波.     

聚丙烯接枝马来酸酐/SiO_2复合载体型钛催化剂制备及表征

可用于负载烯烃聚合催化剂的材料很多,目前无机载体以SiO2和MgCl2最为普遍.但SiO2和MgCl2容易出现团聚现象,特别是由于SiO2表面羟基分布不均匀,会造成载体局部区域的催化剂浓度过大,活性中心过于集中,对烯烃共聚合时共聚单体的分布不利[1].聚合物载体由于表面的官能团分布均匀及分布密度可调,负载后的催化体系对氧、水的稳定性增加.但聚合物载体制备较为复杂,且用研磨法得到的载体颗粒形态及分布不易控制,用于高温聚合时容易破裂.由于无机和有机载体各自具有某些特殊的优点,可以进行互补克服某些不利的因素,因而怎样利用不同类型载体的复配,得到性能优良的复合载体,已成为烯烃催化剂载体化研究的一个重要方向.本文制备了聚丙烯接枝马来酸酐(PMA)/SiO2复合载体,制备了负载化TiCl4烯烃聚合催化剂,其既可以避免由纯无机物为载体而引入过多的无机灰分,又可以避免仅用聚合物为载体而造成的负载率低的缺点,同时保持了无机载体的刚性和聚合物载体官能团的多分布性.     

Two-dimensional non-selfsimilar initial value problem for adhesion particle dynamics

A two-dimensional non-selfsimilar initial value problem for adhesion particle dynamics with two pieces of constant states separated by a circular ring is considered. By using the generalized characteristic method and the generalized Rankine-Hugoniot relation,which is a system of ordinary equations,the global solution which includes delta-shock waves and vacuum is constructed.     

水相配位催化烯烃聚合的新进展*

水相催化研究已经成为近年来化学反应研究的热点课题.烯烃聚合领域中水相自由基乳液聚合和悬浮聚合等方法早已工业化,而前过渡金属烯烃聚合催化剂对水气敏感,水相烯烃配位聚合发展缓慢.低亲氧性、高活性的后过渡金属烯烃聚合催化剂的出现使水相催化成为可能.本文综述了后过渡金属催化剂水相催化烯烃配位聚合的一些新进展,内容包括乙烯、α-烯烃、环烯烃、二烯烃的聚合反应和环烯烃的开环聚合反应以及CO/烯烃的共聚反应等方面.     

Li2O-Nb2O-SiO2系统非晶态离子导体的结构与电学性能

本文采用红外吸收光谱法、X射线散射法和EXAFS方法研究了LiO-Nb₂O-SiO₂系统非晶态离子导体的结构,认为Nb⁵⁺在非晶结构网络中主要是以[NbO₆]形式存在。非晶结构随Nb₂O₅含量的多少而变化。低Nb₂O₅含量时,[NbO₆]相互间以边相连,并与[SiO₄]组成多元环后,形成非晶网络结构。高Nb₂O₅含量时,非晶网络结构主要是以角顶相连的[NbO₆]所组成。根据电导测试结果,讨论了结构与电学性能的关系,认为Li₂O含量在0.45左右,Nb₂O₅,含量在0.3左右组成的非晶材料有最高的电导率。 关键词：