Pt–Ru catalysts supported on carbon xerogels for PEM fuel cells

Pt–Ru electrocatalysts supported on carbon xerogels were synthesized by reduction of metal precursors with formate ions (SFM method). The carbon xerogel was chemically and heat treated in order to evaluate the different procedures to generate oxygenated groups on the surface. Temperature-programmed desorption (TPD) of xerogels showed that heat treatment of previously chemically modified support gradually removes the oxygenated groups from the carbon surface. Physical characterization of the catalyst was performed using X-ray dispersive energy (EDX) and X-ray diffraction (XRD) techniques. Results confirmed that Pt–Ru catalysts with similar metal content (20%) and atomic ratios (Pt:Ru 1:1) were obtained.     

Evaluation of the efficiency of silicone polyether additives as antifoams in crude oil

It is common for crude oil from wells to be accompanied by gas and water because of the presence of natural surfactants in the oil that stabilize the associated water. This causes foaming during processing in gas/oil separators because of the constant agitation and shear forces, which reduce the efficiency of the process and require chemical control by the addition of defoaming additives, or antifoams. In this work, we evaluated the chemical and physicochemical properties of commercial antifoam products based on silicone polyethers along with their efficiency in inhibiting foaming and water/oil (W/O) phase separation. The commercial surfactants were characterized by NMR spectroscopy, size exclusion chromatography, determination of solubility in different solvents, and measurement of the surface and interfacial tensions. A method to test the formation of foam in oil was used to mimic the operating conditions in gas/oil separators. Finally, tests were performed with the addition of aliquots of the additive solutions (30% p/v) in oil to evaluate their efficiency in breaking up the foam under different conditions. The results show that the most polar additive (SL2) was the most efficient in breaking up the foam. Additive SP1, which formed a heterogeneous phase in the oil, was also an efficient foam inhibitor and helped to separate these phases. The antifoam tests showed that these additives did not stabilize W/O emulsions, so they could be used in gravitational separation tanks in the field. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of nano carbon additives on the microstructure of polyvinyl chloride heated up to 2000°C

Polyvinyl chloride (PVC) is one of the most commonly used thermoplastic materials among worldwide polymer consumption. The PVC exhibits particular inherent properties such as low cost and high performance, it can be obtained from different techniques. PVC products will finally become waste. As a result, the quantity of waste PVC is gradually increasing. The waste product PVC can be converted to graphite. Graphitic structure was obtained by carbonization of polymers to 1000°C, and subsequent heating to 2000°C. In this study the effect of carbon nanotube (CNT) and carbon black additives on the graphitic microstructure of PVC polymer was investigated. The solution of PVC in tetrahydrofuran (THF) was prepared then additives were dispersed in solution by ultrasonic. The additives were applied in the concentration between 1 and 3wt%. Changes in graphitic microstructure were studied via Raman spectroscopy, X-ray diffraction, and Transmission electron microscopy (TEM). Morphology of microstructures studies with scanning electron microscopy (SEM). The results show that the additives do not develop the graphitic microstructure and do not improve the formation of flaky graphite crystals.     

国内外润滑油添加剂现状与发展趋势

综述了近年来粘度指数改进剂、极压抗磨剂、清静分散剂、抗氧剂、防锈剂等在国内外的研究现状,并对添加剂的发展趋势进行了展望。     

机制砂超高强高性能混凝土的研制

作者采用常规材料及通用工艺成功地研制成工作性能较好，２８ｄ抗压强度在１００ＭＰａ以上的机制砂高性能混凝土。文章在分析讨论了超细掺合料、水泥品种、村号及水胶比，超塑化剂的种类及掺量，胶结材用量，粗骨料的强度及粒径大小等配比参数对超高强高性能混凝土工作性及强度的影响后，指出了配制这种混凝土的技术途径。     

Slurry Chemistry Control to Produce Easily Redispersible Ceramic Powder Compacts

The slurry-based Three Dimensional Printing (3DP^TM) process requires the production of an easily redispersible powder bed from a well-dispersed slurry. Understanding and control of the interparticle potential in the dispersed state, as well as in the dry consolidated state, are important. The strength of the particle–particle interactions in the dry state determines the redispersion efficiency. One factor that controls the interparticle strength is the chemical stability of the ceramic powders in the dispersed state. For unstable powders, a partial dissolution and/or hydration of the powders can occur and eventually impede the redispersion by forming insoluble salt bridges at the necks of the particles. Redispersion of the powder bed can be improved substantially by weakening the strength of the particle–particle bonds. The formation of strong chemical bonds between particles should be avoided by adjusting the slurry pH to an appropriate range where the powders are chemically stable in the slurry. Replacement of the chemical bonds by soluble physical bonds, using a low-molecular-weight hydrophilic polymer, also reduces the interparticle strength and enhances redispersion.     

硫系极压抗磨剂研究进展

综述了硫系极压抗磨剂的研究进展和发展趋势,介绍了其作用机理及适用范围。根据所含活性元素的不同,硫系极压抗磨剂分为硫型、硫-磷型、硫-氮型、硫-磷-氮型以及硫-磷-硼-氮型。随着现代工业的快速发展,多功能环保型的极压抗磨剂是未来的发展方向,纳米微粒作为极压抗磨剂的研究将受到广泛关注。     

如何进行糖果产品的创新工作

糖果企业针对各自的发展制定一个合理可行的新产品创新大纲,从分析产品竞争领域、明确新产品活动的目标、制定实现目标规划等方面进行创新工作,同时介绍了国际糖果行业使用新型添加剂的信息。     

添加剂对微表处混合料抗车辙性能改善效果的研究

近年来，微表处在广泛用于整幅罩面的同时越来越多地用于车辙修复。微表处车辙修复的主要破坏机制是高温稳定性不足。以改善乳化沥青残留物和微表处混合料高温稳定性为目标，通过乳化沥青蒸发残留物软化点和60℃布氏粘度试验、微表处混合料RLWT车辙试验等，对不同添加剂的改性效果和改性效果变化规律进行了评价，为车辙填充微表处混合料添加剂的选择提供参考依据。