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.     

Study on current–voltage curves of composite bipolar membrane for water and methanol solutions

The current–voltage curves of a composite bipolar membrane (CBM) were experimentally measured by inserting the thin poly(acrylonitrile) (PAN) membrane between cation‐ and anion‐exchange membranes for water and methanol solutions. In each solution system, 0.05 mol/L LiCl was used as the electrolyte. The measured results show that the thin PAN membranes enhanced the water‐ and methanol‐splitting effect. This phenomenon can be explained by the protonation–deprotonation reactions occurring between the functional group of PAN ( CN, cyano) and the water or methanol molecules in the intermediate region of the CBM. The effect of niobium alloy (Nb₃Ga), fullerene (C₆₀) and titanium oxide (TiO₂) existing in the intermediate region of the CBM was also experimentally examined in this study. It was found that the effect of these compounds on water or methanol‐splitting was not obvious. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1597–1604, 2000     

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     

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.     

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     

电磁场强度对层流火焰和NO生成特性的影响

在液化气与空气燃烧的层流火焰两侧施加放电磁场,测定磁场强度,采用双铂铑热电偶和综合烟气分析仪检测层流自由射流火焰温度和NO浓度,分析了不同磁场强度下层流自由射流火焰特性和NO生成特性. 结果表明,在电磁场作用下火焰长度变短,火焰下部直径增大;随磁场强度增大,火焰面下部温度提高. 电磁场可减少火焰中N, HCN, CN等离子和离子团与氧的碰撞几率,导致NO浓度降低,最大下降值为4.26 mg/m3,最大降幅为78.60%.     

Numerical Simulation of S-Shaped Current–Voltage Curves Induced by Electron Traps in Inverted Organic Photovoltaics

Organic photovoltaics (OPVs) differ from their inorganic counterparts because of inevitable electronic disorders and structural heterogeneity. Charge carrier traps are inevitable in organic semiconductors. A common failure mechanism of OPVs is the development of an S-shaped current density–voltage characteristic (J-V curve). Herein, we focus on investigating the underlying physical mechanism of S-shaped deformation of J-V curve of the inverted organic photovoltaic devices with bulk-heterojunction, proven by experiments with the n-doped electron extraction layer and numerical simulations assuming electron traps (0.1 eV deeper) in the electron extraction layer. The numerical simulations are quite consistent with the experimental results. In addition, the open circuit voltage induced by S-kink is exemplified to be enhanced after removing the electron traps in the interlayer by introducing a dopant of cesium carbonate.     

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.     

溴系协效阻燃体系对PP阻燃和生烟性能的影响

利用极限氧指数、锥形量热仪和热重分析等方法对比研究了溴–锑和溴–铋协效阻燃体系对聚丙烯(PP)阻燃性能和生烟性能的影响。结果表明,八溴醚–氧化铋和八溴醚–三氧化二锑阻燃体系能明显提高PP的阻燃性能;当溴–锑和溴–铋阻燃剂的质量比为3∶1时,协同阻燃效果最佳,其中八溴醚–三氧化二锑和八溴醚–氧化铋的协同效率值分别为3.96和4.32。与纯PP相比,八溴醚的加入明显增大了PP的生烟速率(SPR)和总生烟量(TSR),但溴–铋阻燃PP的SPR峰值和TSR相比于溴–锑阻燃PP却分别下降了14.94%和14.32%。热重分析表明,溴–铋阻燃体系相比于溴–锑阻燃体系能较早地释放出HBr,并更大程度地降低PP的热裂解速率,从而更有效地提高溴系阻燃PP的协同阻燃效率并降低生烟量。     

Synthesis of (1,4‐Methylenephenylphosphinic acid) Piperazine and Its Application as a Flame Retardant in Epoxy Thermosets

An efficient flame retardant (1,4‐methylenephenylphosphinic acid) piperazine (MPPAP) is successfully synthesized. The application of MPPAP in epoxy (EP) thermosets increases limited oxygen index values of composites to 30.2% and 6 wt% or more loading makes the materials get through UL94 V‐0 rating. The investigation of the combustion process indicates that MPPAP clearly changes the combustion behavior of EP composites, forms a char layer on the surface of the composites, and presents an effective flame inhibition effect, consequently resulting in clear reduction of the flammability and smoke production. The thermal degradation process of MPPAP/EP indicates that MPPAP promotes the matrix to decompose earlier and increases the char‐forming ability of composites. The morphology and structure of the final char shows MPPAP can promote the formation of cross‐linking structures and increase the graphitization degree of char residues acting as an excellent barrier. Furthermore, the flame‐retardant mechanism illuminates that MPPAP can reduce the generation of volatile fuels, and the pyrolysis products of MPPAP contain PO and PO₂, which exert free radical quenching effect in the gas phase. Therefore, MPPAP is a terrific flame retardant for epoxy thermosets which manifests a flame retarding action in the gas phase and condensed phase.     

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。     

Phosphorus and Silicon Containing Low‐Melting Organic–Inorganic Glasses Improve Flame Retardancy of Epoxy/Clay Composites

New low‐melting organic–inorganic glassy polymers containing phosphorus and silicon are synthesized by the reaction between phenylphosphonic acid and methyltrichlorosilane or methyltriethoxysilane. They possess both low‐softening points and high onset decomposition temperatures, which are favorable for preparing flame retardant composites. Although the glass by itself is sensitive to water, the composites are not significantly affected in that way. For glass/clay/epoxy composites glass transition temperature (T_g) as well as storage modulus increase with the glass amount. The glasses improve flame retardancy significantly due to flame inhibition and the formation of fire residue working as protection layer during burning. The total heat evolved is reduced by 23–28% for using 5–15 wt.% glass and the maximum HRR even by 58–48%. The latter effect decreases with increasing glass amount due to an adulterate residue deformation. The combination of glass and clay is proposed as a possible route to enhance flame retardancy.

     

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.     

The influence of the internal structure of core–shell particles on poly(vinyl chloride)/(methyl methacrylate–butadiene–styrene) blends

Methyl methacrylate–butadiene–styrene (MBS) core–shell particles were prepared by grafting styrene and methyl methacrylate onto polybutadiene seeds via emulsion polymerization. All the MBS particles were designed with the same chemical composition, similar grafting degree but different internal structures. The difference in internal structure was realized by controlling the ratio of ‘external grafting’ and ‘internal grafting’ of styrene. The work focused on the influence of the internal structure of MBS core–shell particles on the properties of poly(vinyl chloride)/MBS blends. From transmission electron microscopy, three different internal structures were observed: rare sub‐inclusions, a large number of small sub‐inclusions and large sub‐inclusions. The results of dynamic mechanical analysis illustrated that the different internal structures greatly affected the glass transition temperature T_g of the rubber phase and the storage modulus of the core–shell particles. The notched Izod impact test results showed that the MBS with large sub‐inclusions had the lowest brittle–ductile transition temperature, while the transparency test revealed that the presence of sub‐inclusions in the rubbery phase reduced the transparency of the blend. Copyright © 2012 Society of Chemical Industry     

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...