中国科大在烯烃配位聚合领域取得新进展

<正>聚烯烃由于其优异的性质和相对低廉的价格,成为现代社会生活不可或缺的一种材料。烯烃聚合研究的一个核心是新型、高性能催化剂的研究。近期,中国科学技术大学化学与材料科学学院和中科院软物质重点实验室陈昶乐教授课题组在烯烃配位聚合领域取得新进展。他们合成了一类新型的二亚胺钯催化剂,首次以此类催化剂得到半结晶性的聚乙烯和乙烯/丙烯酸甲酯共聚物。     

基于聚烯烃的多嵌段共聚物合成方法研究进展

聚烯烃是世界上产量和消费量最高的合成高分子材料,用途广泛,其多嵌段共聚物更具有特殊的性能。基于聚烯烃的多嵌段共聚物近年来所受到广泛关注,文中将从合成方法角度出发,系统综述基于聚烯烃的多嵌段共聚物的制备方法,重点介绍采用活性配位聚合、链穿梭聚合、烯烃复分解反应以及基于链行走机理的烯烃配位聚合合成嵌段数目大于3的聚烯烃基多嵌段共聚物的方法。     

过渡金属催化烯烃聚合

论述了烯烃聚合催化剂的发展更新过程,催化聚合的过程。涉及配位聚合的链增长机理、单体几种可能的插入模式及聚合的立构控制方式、链转移或链终止机理以及可能存在的催化活性中心的失活过程。对于过渡金属催化烯烃聚合的理解有助于催化剂设计的理性化。     

配位聚合制备苯乙烯-异戊二烯-丁二烯三元集成橡胶研究进展

介绍了集成橡胶(SIBR)的概念,详细总结了SIBR的配位聚合制备方法,包括限制几何构型配合物催化配位聚合、钕系催化剂催化配位聚合和链穿梭聚合。展望配位聚合制备SIBR未来的趋势。     

聚ε－己内酯的合成和共聚反应研究

本文就聚ε－己内酯的合成和共聚进行了概述，阐述了ε－己内酯以阳离子聚合，阴离子聚合或配位聚合常用的引发剂和聚合反应的特点。介绍了配位聚合中分子设计的思想和聚ε－己内酯进行共聚改性的方法。     

消息报道

大连化物所甲醇制烯烃基础研究取得突破中科院大连化学物理研究所甲醇制烯烃国家工程实验室(洁净能源国家实验室低碳催化与工程研究部)在甲醇制烯烃工业化过程开发和应用方面取得了令人瞩目的成就。近期,研究人员在甲醇转化机理研究方面又取得了突破性进展。甲醇制烯烃是在酸性分子筛上进行的多相催化反应,经历了一系列复杂的催化过程和反应步骤。随着反应机理研究的不断深入,烃池机理得到了广泛关注。然而,直接的实验证     

浓乳液快速聚合方法制备丙烯腈/丙烯酸丁酯共聚物

研究了丙烯腈／丙烯酸丁酯的浓乳液快速聚合，在绝热环境下反应30min后的单体转化率可达80％。通过研究乳液浓度、共单体的组成与引发剂的组成对反应转化率与共聚物的组成等的影响，确定出一种极性烯烃单体的节能、快速的新型聚合方法。     

膜法烯烃/烷烃气体分离的研究进展

对烯烃/烷烃气体分离技术的现状进行了总结，阐述了膜法烯烃/烷烃气体分离的研究进展、分离原理及存在的问题等．同时展望了膜技术应用于烯烃/烷烃气体分离的前景及研究方向．     

基于促进传递机理的烯烃/烷烃分离用固体聚合物电解质膜的研究进展

对膜法烯烃/烷烃分离技术的现状进行了总结,论述了膜法促进传递分离烯烃/烷烃的机理、研究进展及存在的问题.分析了固体聚合物电解质膜对烯烃/烷烃分离性能的影响因素,探讨了固体聚合物电解质中高分子材料和烯烃载体对膜性能的影响,阐述了烯烃载体Ag+的中毒及再生过程和烯烃渗透的时间依赖性.     

金属卡宾催化剂在烯烃复分解反应中的研究进展

简要介绍了烯烃复分解反应及其反应机理,综述了金属卡宾催化剂在烯烃复分解反应中的研究进展,重点介绍了钨、钼、钌卡宾催化剂的发展和应用,并简述了其他体系金属卡宾催化剂的研究现状,最后指出了金属卡宾催化剂的发展方向。     

提高CO2跨临界循环效率的方法

针对CO2跨临界循环的特征,阐述了几种提高循环效率的方法,其中包括采用涡流管或者膨胀机代替膨胀阀,采用两级压缩、中间冷却技术等等.论述了涡流管代替膨胀阀提高系统效率的方法、原理,并介绍了一种适合小型制冷系统的新型气缸活塞式膨胀机.另外,还叙述了CO2跨临界循环系统采用两级压缩、中间冷却时,最佳中间压力的确定原理以及方法.     

ASTM金属材料拉伸试验方法介绍

介绍了ASTM E8(E8M)标准中的金属材料屈服强度、屈服点伸长率、均匀伸长率、抗拉强度、伸长率和断面收缩率的测量方法，并与我国相应的标准试验方法进行了比较。     

定向控制爆破拆除低矮密集楼群

介绍了一个低矮密集楼群定向控制爆破拆除的实例。该楼群包括 6幢未竣工的钢筋混凝土框架结构楼房。文中讨论了爆破方案和施工程序的确定 ,获取倾覆力矩的方法 ,爆破参数选取 ,爆破网路和起爆方法。此外 ,概述了作者的一些认识和体会     

The application of atomic absorption spectrometry for the determination of residual active pharmaceutical ingredients in cleaning validation samples

The objective of this work was the development and validation of atomic absorption spectrometric (AAS) methods for the determination of residual active pharmaceutical ingredients (API) in rinse samples for cleaning validation. AAS as an indirect method for the determination of API in rinse samples can be applied when it is in the form of salt with metal ions or when the metal ion is a part of the API's structure. The electrothermal AAS methods (aqueous and ethanol medium) for the determination of magnesium in esomeprazole magnesium and the flame AAS method for the determination of lithium in lithium carbonate in rinse samples were developed. Various combinations of solvents were tested and a combination of 1% aqueous or ethanol solution of nitric acid for esomeprazole magnesium and 0.1% aqueous solution of nitric acid for lithium carbonate were found to be the most suitable. The atomization conditions in the graphite furnace and in the flame were carefully studied to avoid losses of analyte and to achieve suitable sensitivity. The cleaning verification methods were validated with respect to accuracy, precision, linearity, limit of detection, and quantification. In all the cases, the limits of detection were at the microgram level. The methods were successfully applied for the determination of esomeprazole magnesium and lithium carbonate in rinse samples from cleaning procedures.     

定向控制爆破拆除低矮密集楼群

介绍了一个低矮密集楼群定向控制爆破拆除的实例。该楼群包括 6幢未竣工的钢筋混凝土框架结构楼房。文中讨论了爆破方案和施工程序的确定 ,获取倾覆力矩的方法 ,爆破参数选取 ,爆破网路和起爆方法。此外 ,概述了作者的一些认识和体会     

基桩声波透射法检测新技术及其应用

声波透射技术检测桩身完整性主要运用数学统计法和PSD斜率法。在声测管彼此不平行或收发换能器不同步时容易造成误判。为了解决上述问题,提出若干新技术,如相对能量法、瀑布图法、三维层析成像分析及采用两个深度编码器实时显示换能器所在位置等有效地改善测试过程和解释精度。通过实际工程的成功应用,试图将上述新技术纳入国内现行规范中。     

REVIEW OF SOME PROCESSES FOR CERAMIC-TO-METAL JOINING

Various methods are discussed for the joining of ceramics to metals and vice versa. State-of-the-art techniques including refractory metallizations and active metal brazing are detailed from both a processing and applications standpoint. Various approaches to forming ceramic/metal joints or thin film coatings have been developed over the years to address the need to combine the properties of both types of materials for both electrical and structural applications. These methods address not only physical and chemical compatibility concerns but also the need for bonds between dissimilar materials to survive the rigors of use generated by such inevitable mismatches as can be found in expansion, elastic, reactive and thermal cycling behavior.     

Measuring volume ratios of vacuum vessels using non-evaporable getters

Several methods have been used in vacuum metrology for volume determination. Volume ratios can be determined by different gas expansion methods, which were primarily developed for the precise determination of expansion ratios in static expansion systems. Measurements of the volume ratios using the gas expansion methods below 10⁻² Pa are influenced by outgassing from chamber walls. To reduce outgassing in the expansion chambers during measurements at low pressures, we have installed non-evaporable getter (NEG) pumps, which pump hydrogen and other active gases but have a negligible pumping speed for inert gases. The volume ratio of two chambers of an experimental static expansion system has thus been measured using the inert gases argon, helium and krypton. The obtained results were compared with the measurements without the use of an NEG pump. Measurements of the pressure ratios were performed with a spinning rotor gauge (SRG).     

无机抗菌剂及其加工品抗菌效力评价

本文主要综述了无机抗菌剂对细菌的作用及近年来国内外常用的抗菌试验方法和抗菌效力判定基准 ,并且总结了不同加工品的适用检测方工。     

A status report on delamination resistance testing of polymer-matrix composites

The development of fracture mechanics test methods for the determination of delamination resistance or fracture toughness of fiber-reinforced, polymer-matrix composites is an active area of research. The emphasis in this review is on standardisation of test methods. Recent developments leading towards new standardized test procedures will be presented, complementing and updating earlier reviews.