Sulfonated poly(arylene ether sulfone) as an electrode binder for direct methanol fuel cell

Sulfonated poly(arylene ether sulfone) (sPAES) is synthesized and characterized for the application to the electrode binder for direct methanol fuel cell (DMFC). The effect of sPAES binder in the electrode on the cell performance is studied. The cell based on sPAES binder showed a good adhesion to the sPAES membrane, while Nafion binder is delaminated from the sPAES membrane after supplying the fuel for a prolonged time. The sPAES binder for electrode is found to be more efficient in achieving long-term stability of the cell performance than the conventional Nafion binder.     

The effect of hydrophobicity in alkaline electrodes for passive DMFC

The effect of hydrophobicity in alkaline electrodes has been investigated in an effort to improve their performance in passive direct methanol fuel cells. Two approaches have been used to increase the hydrophobicity within the electrodes. One is using a more hydrophobic ionomer, and the other is introducing polytetrafluoroethylene (PTFE) into the catalyst layer. Two types of anion exchange ionomers with different hydrophobicity have been synthesized for this study. The effect of ion exchange capacity, ionic conductivity, and water uptake of the ionomers on the electrode performance has been studied using a half-cell test. The use of a hydrophobic ionomer resulted in enhanced cathode performance even though the ionic conductivity was lower than the more hydrophilic ionomer. Also, the addition of PTFE improved both the cathode and anode performance. The improved alkaline electrode performance was compared to a traditional acid electrode using Nafion as the ionomer. The performance increased threefold as a result of higher hydrophobicity in alkaline electrode.     

胶粘剂对粘接NdFeB磁体性能的影响

胶粘剂是影响粘接磁体性能的关键因素。本文研究了胶粘剂种类和胶粘剂用量对粘接磁体磁性能的影响。结果表明，环氧值较高且与磁粉表面相容性好的树脂是制备粘接磁体的理想胶粘剂，胶粘剂质量分数为2％～3％时，磁体性能最佳。     

Measurement of single electrode potentials and impedances in hydrogen and direct methanol PEM fuel cells

A commercial proton exchange membrane fuel cell has been fitted with a simple dynamic hydrogen reference electrode (DHE). Single electrode potentials and impedances measured with hydrogen and methanol as the fuel have been critically evaluated. It has been shown that the anode overpotential and impedance can be very significant in hydrogen cells operated at ambient temperature, due to dehydration of the anode. The DHE provides a powerful way of monitoring the hydration state of the membrane and electrodes, so that operating conditions can be adjusted to optimise water management. Individual electrode potentials and impedances are even more important in methanol cells, and can be conveniently measured with the DHE.     

对苯乙烯磺酸钠对涂料印花粘合剂性能的影响

为了制备粒径在纳米级的涂料印花粘合剂,本文在聚合中以反应性乳化单体对苯乙烯磺酸钠（SSS）、十二烷基硫酸钠（SDS）和平平加O（O—5）为复合乳化剂,SSS一方面起着乳化剂的作用,另一方面又可以作为单体参与聚合反应。通过对乳液及其胶膜性能测试、粒度分析以及涂料印花应用试验等手段,研究了sss对乳液及胶膜性能的影响。结果显示,本文合成的粘合剂乳液用于涂料印花,织物获得了良好的摩擦牢度和水洗牢度,并且手感柔软。     

硅系黏结剂对涂覆型蜂窝体催化剂性能的影响

以黏土蜂窝体为廉价载体浸涂V–W–Ti催化剂浆料,制备涂覆型蜂窝体催化剂。考察了涂覆型蜂窝体催化剂制浆过程中分散剂、黏结剂、增强剂等因素,并通过XRF, XRD, BET及SEM等手段对其表征。结果表明,黏结剂对催化剂脱硝活性和强度影响最大,黏结剂B3制备的涂覆型蜂窝体催化剂脱硝活性和强度最优,表面形成了致密的涂层,具有更高的强度。在优化参数条件下制备的涂覆型蜂窝体催化剂单孔道NO转化率达20.3%,优于商用挤出型蜂窝体催化剂(NO转化率18.1%,单孔道),其催化剂用量显著降低。耐磨测试结果预测所制涂覆型蜂窝体催化剂在焦化厂烟气条件下稳定工作时长预期达128000 h,极具工业应用前景。     

黏结剂与阻熔剂对兰炭成型及熔融特性的影响

将大量粒径小于3mm的废弃兰炭粉末制气化型煤既可以降低气化型煤的成本,也充分利用了资源。本文采用常温加压成型工艺,重点研究了不同黏结剂对型煤性能的影响,并考察了添加阻熔剂后兰炭灰渣熔点的变化情况。结果表明,在相同添加量下,有机黏结剂制备的型煤落下强度大,但热稳定性差;而以无机黏结剂制备的型煤落下强度小,影响型煤热值,但热稳定性好。黏土1（wAl2O3>60%）既有黏结性能,又能很好地提高煤灰熔融特性。将腐殖酸钠、淀粉、黏土1复合黏结剂可以使兰炭型煤落下强度和灰熔点满足气化型煤的要求。     

Effect of cathode GDL characteristics on mass transport in PEM fuel cells

The effect of the content of the hydrophobic agent in the cathode gas diffusion layer (GDL) on the mass transport in the proton exchange membrane fuel cells (PEMFCs) was studied using mercury porosimetry, scanning electron microscopy, and electrochemical polarization techniques. The mercury intrusion data and SEM micrograph indicated that the hydrophobic agent alters the surface and bulk structure of the GDL, thereby controlling gas-phase void volume and liquid water transport. The electrochemical polarization curves were measured and quantitatively analyzed to determine the oxygen transport limitation both in the catalyst layer and the GDL. Evaluation of the parameter ζ, which represents the cathode GDL characteristics for liquid water transport, indicated that the optimized content of the hydrophobic agent and effective water management results from a trade-off between the hydrophobicity and the absolute permeability for faster water drainage.     

Characteristics of the carbon paper heat-treated to different temperatures and its influence on the performance of PEM fuel cell

Porous conducting carbon paper acts as an electrode backing material in a fuel cell. It not only assists in the flow of electrons and gases but also provides mechanical support to the MEA. The electrically conducting carbon paper (porosity ∼70%) was prepared using laminated assembly of chopped carbon fiber porous preforms and applying combined paper making and composite making technique. The green paper was subjected to different heat treatment temperatures (HTT), which was found to influence the characteristics of the paper significantly. The processing of the paper was carried out at a very fast carbonization rates, 900 °C/h as compared to 10-20 °C/h used conventionally, making the complete process highly cost efficient. The paper when used in the unit fuel cell assembly showed I-V performance comparable to that of the commercially available Toray carbon paper.     

The Effect of Methanol Crossover on the Cathode Overpotential of DMFCs

The effects of methanol crossover on cathode overpotential of direct methanol fuel cells (DMFCs) were investigated by focusing on a mixed potential effect and surface poisoning of the catalyst. Experiments using different membranes and catalyst loadings were performed and compared with a semi‐quantitative model to discuss the main cause of the cathode overpotential. When the measured methanol crossover increased, cathode overpotential increased at particular threshold values, which were 150 mA cm^–2 at 0.3 mg cm^–2 of cathode platinum (Pt) loading and above 200 mA cm^–2 at 1.1 mg cm^–2. The modelling results also supported this tendency, and showed that Pt surface was poisoned to a great extent above the threshold methanol crossover where the cathode overpotential increased sharply, while the cathode overpotential remained low and was explained solely by the mixed potential below the threshold value. The threshold methanol crossover can be regarded as the acceptable value, below which the cathode overpotential from methanol crossover remains low, and was related with the Pt loading in the cathode. The reduction of methanol crossover through membranes below the acceptable values will contribute greatly to a decrease in the cathode overpotential and to the reduction of catalyst loadings.     

Effect of chemical composition on gas transport properties of ethylene-based ionomers

Transport properties of oxygen and carbon dioxide in three ethylene–acrylic acid ionomers, characterized by different amounts of acrylic acid groups, percentage of neutralization and counterion type, have been investigated. Gas permeation experiments have been performed in the 25–65°C range. Gas permeabilities, diffusivities and solubilities were evaluated along with activation energies and heats of solution. The transport properties have been analysed in order to correlate the effect of counterion type and its concentration on macromolecular mobility and on polymer–gas interaction, which in turn are the factors determining permeation rate.     

复合型煤粘结剂的成型及固硫效果研究

采用一种新型复合粘结剂制备生物质型煤,并通过实验证明其可行性。该复合粘结剂主要由改性后的生物质和无机固化剂组成,采用SEM扫描电子显微镜和EDS能谱检测分析型煤的形貌结构和成分组成,研究复合粘结剂各成分对型煤成型的影响。燃烧前后元素分析得出该复合粘结剂对燃烧前后煤中硫元素的影响。结果表明,复合粘结剂增强了型煤的抗压强度;起粘结作用的主要元素为Mg、Cl;添加复合型煤粘结剂后,固硫率为34％,固硫最终产物为MgSO4,具有良好的固硫效果。     

SCC-1型高效复合黏结剂在型焦生产中的应用

为了解决焦粉的再利用问题,提高能源利用效率,缓解焦粉露天堆放造成的粉尘污染,采用无机矿物质和有机高分子化合物复配制得SCC-1型复合黏结剂用于焦粉成型生产型焦。研究了焦粉的成型工艺,对工艺路线和工艺参数进行了选择和优化。用SEM分析了型焦的成型机理,并对型焦的性能进行研究。结果表明：采用SCC-1型复合黏结剂制备型焦,具有成型工艺简单,黏结剂用量少,不需要烘干工序,设备投资少,生产成本低等优点,大部分焦粉颗粒被SCC-1型复合黏结剂润湿后通过“黏结剂固体桥”连接而成型,制得型焦的冷压强度、落下强度、耐水性、热稳定性、反应活性等性能指标均满足工业生产工艺要求,具有很高的推广应用前景。     

Effect of ternary binder on the mechanical and microstructural properties of sand concrete

The present work focuses on the study of effect of the cement content (C), lime (L) and pozzolan (P) as well as the effect of their combinations C*L, C*P and L*P on the mechanical and microstructural properties of sand concrete based on a ternary binder using the ‘mixture design’ method. C, L and P were taken as independent variables, while the flexural strengths (Rf) and the compressive strengths (Rc) at 7 and 28 days were taken as responses. Mathematical models were determined. The obtained results showed that the most significant variable that affects all the studied responses is the cement content. The SC09 (100% C) presented the highest values. However, the SC08 (80% C + 20% L) ranks second and the SC13 (80% C + 20% P) ranks third in terms of mechanical strength. But SC08 and SC13 provided 20% of cement economy, while the minimum values of mechanical strength were recorded in the case of SC17 (100% L), which means that a high rate of lime has relatively a negative influence on the mechanical strength. On the other hand, the X-ray diffraction study showed that the type of the resulting hydration products and their quantities depend on the proportions of C, L and P, which justifies the changes recorded in the properties studied. Finally, the microscope visualization showed also that the material appears relatively homogeneous and dense with a good adhesion paste-aggregate, either in the case of cement or pozzolan or lime.     

黏结剂对长焰煤制备民用洁净焦炭强度的影响

在我国广大农村地区,居民仍使用劣质散烧原煤,严重破坏了大气环境。提供优质的煤基洁净燃料是从源头上解决劣质煤散烧所带来环境问题的重要手段之一。但由于传统民用炉具为层燃式,对所用燃料具有强度和块度的要求。因此,如何保证燃料的成型与强度是一个关键问题。基于此,本文以长焰煤为原料,与复合助剂先经冷压成型,再通过热解制备得到洁净焦炭。同时,系统地研究了复合黏结剂添加量、热解温度等对洁净焦炭强度的影响。结果表明：加入1%聚乙烯醇（PVA）、30%洗油渣（WOR）,在800℃下可得到抗碎强度为94.7%的洁净焦炭,可满足相应的强度要求。复合添加剂中的PVA为冷态黏结剂,其遇水会在煤粒间形成高黏性网状胶体,促使煤颗粒之间黏结,保证其冷态强度。而WOR为热态黏结剂,其在高温热解过程将转化为高黏结性的类胶质体,将原本松散的、无黏结性的惰性颗粒黏结,最终形成高强度的民用洁净焦炭。该研究对高强度民用洁净焦炭的制备提供理论指导。     

粘接剂对热化学反应陶瓷涂层结构与性能的影响

采用相同的陶瓷骨料(SiO2+Al)、添加剂(MgO+CrO3)和固化工艺,分别以磷酸铝和水玻璃为粘接剂,在Q235钢上制备陶瓷涂层,对其相成分、微观形貌、热震性能以及耐蚀性能进行了分析测试,讨论了粘接剂对涂层耐蚀性的影响。结果表明,尽管以磷酸铝为粘接剂的陶瓷涂层在固化过程中产生少量孔隙,但仍具有比以水玻璃为粘接剂的陶瓷涂层更优异的抗热震性能以及耐酸、碱、盐腐蚀性能。     

浸渍剂沥青和黏结剂沥青渗透性对比研究

选择两类具有相近流变性能的黏结剂沥青和浸渍剂沥青,模拟炭材料的微孔分布测定了两类沥青的渗透率,对比研究了浸渍剂沥青和黏结剂沥青的渗透性能差异。结果表明,浸渍剂沥青的渗透性能远优于黏结剂沥青,浸渍剂沥青的渗透率为黏结剂沥青相应值的3.54~22.13倍,两类煤沥青的渗透性差异是由于其QI含量不同造成的,浸渍剂沥青极低的QI含量(0.2%以下)大大降低了煤沥青向多孔滤材中的渗透阻力,为提高浸渍效果创造了有利条件。     

The effect of the Pt deposition method and the support on Pt dispersion on carbon nanotubes

Carbon nanotube supported platinum (Pt/CNTs) catalysts prepared by different Pt deposition methods and on different CNT supports were studied. Colloidal based methods were demonstrated to be more effective than other wet chemistry deposition methods (e.g., impregnation and precipitation) for the preparation of highly dispersed Pt/CNTs. Pt catalyst supported on CNTs with a dispersion uniformity comparable to that supported on carbon powder was achieved using a zwitterionic surfactant 3-(N,N-dimethyldodecylammonio) propanesulfonate (SB12) as stabilizer in a monitored pH environment. It was experimentally observed that oxygen-containing surface functionalities on CNTs can greatly affect the catalyst particle dispersion by manipulating Pt anchoring and/or nucleating sites. Furthermore, it was revealed that the performance of Pt/CNTs based fuel cell is strongly dependent on the electrode fabrication method.     

Mesoscale dynamic simulation on phase separation between plasticizer and binder in NEPE propellants

It has been found that phase separation between polymer binder and small molecular plasticizer has an important effect on the properties of nitrate ester plasticized polyether (NEPE) propellants. However, the phase separation mechanism and factors of influencing the phase separation have not been clarified yet. To shed some light on this issue, a simple and novel method, that is Dissipative Particle Dynamics (DPD) mesoscale simulation, was used to study the influence of temperature and chains length on the phase separation behavior between binder and plasticizer. The results indicated that the temperature is the key factor in controlling the moving speed of molecules in NEPE propellants system. While the interaction between binder and plasticizer plays an important role on the phase separation. With temperature decreasing, the phase separation takes place later and the extent of phase separation is higher. Within a range, when the length of polymer chains is larger, the occurrence of phase separation is earlier. However, for long chains system, the phase separation is less completely than that of the short chains system when the process reaches equilibrium.     

Experimental study of fibers in stabilizing and reinforcing asphalt binder

This investigation examines fibers’ physical properties, reinforcing effects and mechanisms for stabilizing and reinforcing asphalt binder. Laboratory tests of water absorption, mesh-basket draindown, and oven heating were designed and performed on five fiber types (two polyesters, one polyacrylonitrile, one lignin and one asbestos), to evaluate their wettability, asphalt absorption and stabilization, and thermostability, respectively. The cone sink experiment was designed to study fiber modified asphalt’s resistance to flow, and the standard dynamic shear rheometer test was conducted to evaluate fiber modified asphalt’s rheological properties and rutting resistance. Fibers’ microstructures and spatial network formed in asphalt binder were observed using Scanning Electron Microscopy (SEM). Results indicate that fibers can effectively improve asphalt binder’s resistance to rutting and flow, and dynamic shear modulus. Fiber reinforces asphalt matrix through its functions of spatial networking, adhesion and stabilization of asphalt binder. Polyester and polyacrylonitrile fibers seem to have greater network effect than the lignin and asbestos fibers, and their antenna features at fibers’ ends further strengthens this effect. The lignin fiber has the highest water absorption while lowest thermostability. The lignin and asbestos fibers pose greater effects of asphalt absorption and stabilization than do polymer fibers.