SPACE CHEMISTRY RESEARCHES IN CHINA DURING 2000-2001

Over the past two years, significant progress in space chemistry has been made in China. The research fields include meteorites, pre-solar materials, science researches of the moon, effects of the space debris on space environment, and heterogeneity of the Earth. Chinese Lunar Exploration Project Some studies are also dedicated to one important space mission "Chinese Lunar Exploration Project". In this paper, the main achievements are outlined, and some concepts and hypotheses are briefly revised.     

A Review of Hypervelocity Debris Testing at the Air Force Research Laboratory

In this paper, we describe a compact, low cost, fast turn-around-time technique used at the Air Force Research Laboratory to study hypervelocity debris impact effects on spacecraft structures and components. The technique described was used to study debris effects in the areas of: shock physics, debris-produced contamination, chemical analyses of the impact ejecta and debris initiated spacecraft discharge. Examples of research results obtained with the technique are presented and illustrate problems encountered in the field of space debris effects on spacecraft.     

典型煤种的激波管热解动力学研究

通过对三种典型国产煤样在激波管所产生的高温条件下进行的热解过程研究(激波管内径70mm,采用 He/Ar 驱动,热解时间2ms 内,热解温度1700K),给出了三种煤热解析出的多种组分的时间历程,提出了相应的组分产量预测模型,并讨论了影响热解组分产量的环境压力、粒度和挥发组分的再分解等普遍关心的问题。     

电性拓扑态指数预测硝基类含能材料撞击感度

应用电性拓扑态(E-state)指数模拟分析了硝基类含能化合物的撞击感度,采用逐步回归构建了5个变量的定量结构-性质相关模型,模型的相关系数和标准偏差分别为0.907和0.1713,交叉验证相关系数及均方根误差分别为0.941和0.1869,模型具有较高的可靠性、相关度和预测能力。模型分析表明,电性拓扑态指数与硝基类化合物的撞击感度有较好的相关性,原子的电性状态是影响撞击感度的重要因素。     

湍流脉动对化学反应影响的数值研究

为了研究湍流脉动对化学反应的影响,在对冲火焰中引入了时空发展的扰动,其中H₂O₂扰动模拟组分脉动,拉伸率扰动在燃料和氧化剂边界温度均匀的条件下模拟速度脉动,在非均匀条件下模拟温度脉动。正庚烷自点火的计算结果显示:H₂O₂扰动可以缩短点火延迟时间。通过RO₂同素异形化以及C₂H₃氧化的反应路径通量分析,发现H₂O₂扰动不会改变反应路径间的极限竞争关系。均匀温度边界条件下的拉伸率扰动通过恶化热量和自由基的损失抑制中温机理,延长点火所需时间。非均匀温度边界条件下的拉伸率扰动能产生附加的温度扰动,点火延迟时间随扰动频率的变化关系复杂。通过RO₂同素异形化的反应路径通量分析可知,该扰动能够改变反应路径间的极限竞争关系,也能逆转点火进程。由此可以推断,在工程应用中,若湍流脉动较强,点火可能会从单级转化为多级。      

基于点击化学反应的键合剂应用研究

为改善ADN基三唑交联固化体系固体推进剂的粘合剂/固体填料间的界面作用,提高其力学性能,设计合成了基于点击化学反应的键合剂N-炔丙基-2,2'-二羟乙基胺(BA-2)、N-炔丙基-3,3'-二丙腈基胺(BA-7),并采用DSC证明2种键合剂与ADN具有良好的相容性;采用DSC和FT-IR表征了键合剂与以GAP为代表的含能粘合剂的反应性,二者可在60℃进行成环反应;测试并计算了键合剂与ADN的界面特性参数,证明BA-2和BA-7与ADN有较好的吸附作用,有望在ADN基三唑交联固化体系取得应用。     

二(2,2-二硝基丙基)硝胺的合成及热性能

以2,2-二硝基丙醇为原料,经缩合、硝化反应合成了二(2,2-二硝基丙基)硝胺(BDNPN)。用红外光谱、核磁共振、元素分析对中间体及目标化合物的结构进行了表征。优化了反应条件,硝化反应的最佳条件为nBDNPA:nHNO3=1∶30,反应温度为50℃,反应时间为1 h,收率92.1%。用DSC和TG-DTG考察了目标化合物的热性能。结果表明,BDNPN的热分解峰温为212.3℃,具有较好的热稳定性。     

Plasma chemical reactions in C2H2/N2, C2H4/N2, and C2H6/N2 gas mixtures of a laboratory dielectric barrier discharge

Plasma chemical reactions in C₂H₂/N₂, C₂H₄/N₂, and C₂H₆/N₂ gas mixtures have been studied by means of mass spectrometry at a medium pressure of 300 mbar in a laboratory dielectric barrier discharge. A major reaction scheme is production of larger hydrocarbons like C_nH_m with n up to 12 including formation of functional CN groups.     

正交实验法引入应用化学综合实验

介绍了在应用化学综合实验教学中,针对低分子量聚丙烯酸的合成及分析的实验进行教学改革。采取改变教材中实验条件设计正交实验的教学方法,有利于提高学生的科研能力。     

Secular variations of OH nightglow emission and of the OH intensity-weighted temperature induced by gravity–wave forcing in the MLT region

Secular variations of OH airglow (8,3) band and of the intensity-weighted temperature induced by a gravity wave packet at three latitudes in the northern hemisphere in the Mesosphere/Lower Thermosphere region are investigated using a 2-D, time-dependent, fully nonlinear OH chemistry–dynamics model. A net-cycled average survives due to wave transience and dissipation. The integrated OH (8,3) volume emission rates show a 20 percent increase induced by the wave packet. The corresponding intensity-weighted temperature shows an initial increase up to 2 percent then a gradual decrease for the remainder of the simulation time by the same wave packet. These secular variations could be mistaken as long-period or short-period waves in the airglow observations. Therefore, care must be taken when analyzing the data from observations.