双基推进剂燃烧火焰温度CARS测定技术

得到了双基推进剂燃烧火焰CARS实验谱图及相应的温度拟合值。实测结果表明,燃烧火焰平衡区的CARS实验拟合温度数值与相应的热力学计算温度值基本吻合,连续采集的CARS谱显现的温度梯度说明CARS技术可以应用于推进剂燃烧火焰温度的实时诊断。     

Schottky–Richardson,Poole–Frenkel,and Space Charge Limited Current Mechanisms in M‐Type Sr(MnTi)xFe(12‐2x)O19 Ferrite

The Static Current Density–Electric Field characteristics of Sr(MnTi)_xFe_(12‐2x)O₁₉ ferrite compositions (x = 0.5, 1.0, 1.5, and 2.0) have been investigated from 4.15 to 36.30 kV/m at room temperature. Ohmic and nonohmic regions are observed at low and high field regimes. The various models, governing nonlinear conduction, are discussed qualitatively in terms of Space charge limited current (SCLC), Ionic hopping, Poole–Frenkel, Schottky–Richardson, and Fowler–Nordheim mechanisms. The results depict Child‐Langmuir type SCLC in the investigated compositions.     

阻燃剂的发展及其在阻燃塑料中的应用

综述了我国阻燃剂的生产应用情况,描述了阻燃剂家族中的溴系、磷系、三嗪系、硅系、膨胀型、无机填料等系列产品的应用特点。同时就常用的PP、PE、PVC、PS、HIPS、ABS、聚酰胺、PC、PBT、PET、不饱和聚酯、PU和环氧树脂等热塑性通用塑料、热塑性工程塑料和热固性塑料中的阻燃技术进行了初步介绍。     

Electrochemical characterization of vacuum plasma sprayed thin-film solid oxide fuel cells (SOFC) for reduced operating temperatures

This paper focuses on the electrochemical characterization, such as current–voltage measurements, impedance spectroscopy and long-term operation of completely plasma-sprayed SOFC assemblies for a planar metallic substrate-supported thin film concept. The influence of the variation in operating conditions is presented. To determine the different resistances in the cells, the measured impedance spectra were fitted to an equivalent circuit. This enables further improvement of the electrochemical performance of the cells and allows the assembling of high performance SOFC stacks.     

常规氢火焰离子化检测器用于便携式气相色谱仪的可行性讨论

讨论并优化建立了满足便携式气相色谱仪要求的常规氢火焰离子化检测器的相关操作参数。基于实验室气相色谱仪使用的常规氢火焰离子化检测器,考察氢气、空气、辅助气和检测器温度对它性能的影响。在优化后的便携式操作参数下,检测器的线性范围可达107,检出限低至1.4×10-12g/s,以115μg/m L n-C12H26为样品,其峰面积重现性优于0.4%(n=8);相对于常规操作参数,FID的气体消耗降低了75%以上,仅需氢气和空气两种气体;无需额外研制微电流放大装置,易于直接集成于第三方便携式气相色谱仪。     

有机酸钾盐对气溶胶发生剂的消焰降温作用研究

研究了有机酸钾盐对于一种烟火型气溶胶发生剂 (EBM灭火剂 )的消焰降温作用 ,对比分析了不同有机酸钾盐在不同添加量时的改性效果     

乳化燃油火焰温度测定的简易方法

为弥补一般光度法测乳化燃油火焰温度的不足,本文结合最新国外文献,设计了一种测定乳化燃油火焰温度的简易方法,以活塞式燃烧管为燃烧器,用细丝热电偶测火焰温度,利用小烟囱减少外界风及气流对火焰的影响,促使火焰正常燃烧。文中给出了试验装置图,并对此法的特点进行了比较和讨论     

Characterization of membrane electrode assemblies in polymer electrolyte fuel cells using a.c. impedance spectroscopy

The most common methods used to characterize the electrochemical performance of fuel cells are to record current–voltage U(i) curves. However, separation of electrochemical and ohmic contributions to the U(i) characteristics requires additional experimental techniques. The application of electrochemical impedance spectra (EIS) is an approach to determine parameters which have proved to be indispensable for the development of fuel cell electrodes and membrane electrode assemblies (MEAs). This paper proves that it is possible to split the cell impedance into electrode impedances and electrolyte resistance by varying the operating conditions of the fuel cell (current load) and by simulation of the measured EIS with an equivalent circuit. Furthermore, integration in the current density domain of the individual impedance elements enables the calculation of the individual overpotentials in the fuel cell and the determination of the voltage loss fractions.     

阻燃剂应用研究综述

综述了主要无机和有机类阻燃剂的阻燃机理及应用,介绍了国内外目前在阻燃剂方面研究的新情况及广泛应用于阻燃的技术,并展望了阻燃剂的未来发展趋势.     

PET工程塑料用无卤阻燃剂研究进展

综述了PET工程塑料用无卤阻燃剂的研究进展,包括磷系、氮系、无机纳米粉体及其复配阻燃剂。讨论了上述几种阻燃剂的阻燃机理及应用情况,并预测了其今后的发展方向。     

Stability of a Spontaneous Vortex Structure in Flame under Gas Oscillations

The stability of a spontaneous vortex structure formed during combustion of a gas injected through a round hole in a flat horizontal plate onto its lower surface was studied. The unsteady velocity, vorticity, temperature, and pressure fields in the vortex structure were studied experimentally and numerically. It is established that for Reynolds numbers Re 10–75 and Rayleigh numbers Ra 10³ – 10⁴, the vortex structure is stable against single velocity perturbations and changes under acoustic oscillations with a frequency of 100 – 150 Hz. Small cells whose dimensions are comparable with the flame front thickness are destroyed, and the velocity of the vortex gas flow in large cells changes with the frequency of forced oscillations. The amplitude of linear gas velocity oscillations in the vortex is larger than that of gas velocity oscillations in the burner nozzle. It is assumed that the observed increase in the amplitude of gas velocity oscillations in the vortex is due to both acceleration of the combustion products in the gravity field and their thermal expansion. The gas velocity oscillations in the vortex structure lag behind the gas flow rate oscillations by a quarter of the period.     

RoHS指令与阻燃塑料的发展

综述和分析了下述几方面的问题及有关进展:1)RoHS指令的主要内容及其对十溴二苯醚的豁免;2)正在进行危害性评估的阻燃剂;3)RoHS指令及WEEE指令对阻燃塑料的影响;4)中国电子电气行业用阻燃塑料面临的挑战。     

高效液相色谱—氢火焰检测器测定柴油烃族组成研究

近年来,全球性城市空气污染问题日益严重,许多国家都在研究或启动控制空气质量的项目,由于石油燃料的使用是导致大气污染的主要原因之一,因此为了使用清洁燃料而对燃料配方进行调整便是采取的一项主要措施。例如在我国主要城市,含铅汽油已被禁止使用。柴油是目前使用...     

阻燃剂十溴二苯乙烷的市场现状分析及展望

分析了阻燃剂在塑料市场的发展趋势,并以溴系环保型阻燃剂十溴二苯乙烷的特点为基础,分析了十溴二苯乙烷及溴系阻燃剂的发展方向,并对十溴二苯乙烷的规模做出了统计和展望。     

阻燃剂聚季戊四醇磷酸酯的合成及表征

以季戊四醇、三氯氧磷为原料,采用无溶剂法首先合成了季戊四醇二磷酸酯二磷酰氯(PDD),n(季戊四醇)n∶(三氯氧磷)=1 5∶,收率为84%;然后以PDD和对苯二酚为原料,乙腈为溶剂,三乙胺为缚酸剂,在氮气氛围下合成了低聚阻燃剂聚季戊四醇磷酸酯,n(PDD)∶n(对苯二酚)=1∶1,收率为79%。采用红外光谱、磷谱、热重分析和差示扫描量热法对聚合物的结构和热行为分别进行了表征和研究。结果表明,该聚合物具有较高的玻璃态转变温度(Tg=231℃),聚合物质量损失5%时的温度为301℃。当聚合物被加热到600℃时,其炭残留物的质量分数为46.4%。     

硅系阻燃剂阻燃PC及PC/ABS复合材料研究进展

综述硅系阻燃剂阻燃聚碳酸酯(PC)及PC/丙烯腈-丁二烯-苯乙烯塑料(ABS)复合材料的机理,以及无机硅、有机硅氧烷类、聚倍半硅氧烷及其衍生物、有机/无机杂化硅材料、带有双螺环磷酸酯和磷杂菲的硅系阻燃剂等在PC及PC/ABS复合材料中的应用进展。指出硅系阻燃剂是PC及PC/ABS复合材料用阻燃剂的发展趋势。     

新型膨胀型阻燃剂的合成

采用甲醇作为分散剂，以磷酸、季戊四醇和三聚氰胺为原料，在反应温度为80℃、反应时间为6h的条件下合成了季戊四醇磷酸酯三聚氰胺盐（PPM），对产物进行了元素分析、TG等分析和表征，并对其阻燃性能进行了测试。热失重分析显示产物分解温度约为300℃，且具有较好的膨胀度和成炭率，当PE：PPM（质量比）为7：3时，阻燃PE的阻燃性达UL-94V-0。实验表明，反应物的物质的量比对PPM的膨胀度及成炭率有较大影响，最佳物质的量比是n（磷酸）：n（季戊四醇）：n（三聚氰胺）为2．5：1：（1．3～1．7）。     

Some Phenomena During Flame Propagation in a Half‐Open Channel with an Obstacle

A laminar flame front propagating in a closedend channel with an obstacle is simulated. Ignition is initiated at the closed end of the channel. The simulations revealed the entrainment of the flame in the vortex behind the obstacle, the expulsion of the vortex from the channel by the flame, and flame fragmentation.