分散剂对亚微米氮化硅粉体分散性能的影响

本文利用研磨机将氮化硅（Si3N4）粉体研磨至亚微米级，并分析分散剂对Si3N4颗粒粒度的影响。从四甲基氢氧化铵（TMAH）、六偏磷酸钠（SHMP）和Darvan—C这三种分散剂对亚微米SbN4分散性能的曲线图中可以看出．TMAH、SHMP和Darvan—c都有很强的抑制沉淀的作用，对亚微米Si3N4的分散效果较好。SHMP的加入量在1％时出现最佳值，随着加入量的逐渐增加，亚微米Si3N。的分散效果也逐渐变差。比较这三种分散剂，0．4％的Oarvan—C对亚微米Si3N4的分散效果优于1％的SHMP和0．8％的TMAH对Si3N4的分散效果。     

分散剂的结构对苯乙烯/丙烯腈在聚醚多元醇中分散共聚合的影响

将马来酸酐接枝到聚醚多元醇(PPO)中,并经端基环氧丙烷化和异构化反应,合成了不同结构的大分子齐聚物,并用于苯乙烯/丙烯腈在聚醚多元醇中的分散聚合,合成了聚合物多元醇(POP)。采用核磁共振分析表征了大分子齐聚物的结构和异构化程度;采用透射电子显微镜、激光粒度分析,对POP中粒子的微观形貌、粒径(D(4,3))大小及其分布(PDI)进行了表征。结果表明,大分子齐聚物中反式结构含量越高,所合成POP中粒子的D(4,3)及其PDI越小;随着大分子齐聚物用PPO官能度由2增加到6,支链分子量由1000增加到2000,POP中粒子的D(4,3)和PDI越小;随着D(4,3)和PDI的减小,POP体系的粘度显著降低。     

Tetraalkylammonium and phosphonium salt for asphaltene dispersion; experimental studies on interaction mechanisms

Asphaltenes deposition is one of the most severe problems in the petroleum industry, imposing high costs on oil producer companies. The use of chemical dispersants reduces the risk of asphaltene deposition. For this purpose, a variety of chemicals with different structures and functional groups were designed and synthesized. Organic quaternary salts, such as ionic liquids, have been widely used to control asphaltene deposition over the last two decades, but the mechanism of their interaction with asphaltene has not been studied in detail. In this study, the interaction of ten commercial quaternary ammonium and phosphonium salts with asphaltene molecules was investigated using ultraviolet-visible (UV-Vis) spectroscopy. It was observed that the size, shape, and hydrophobicity of their cations or anions play an essential role in the dispersion of asphaltene aggregations. The results showed that the interaction of these quaternary salts is strongly influenced by the hydrophobic nature of the salt, and salts with more hydrophobic cations and anions, such as tetrabutylammonium iodide, tetrabutylammonium hexafluorophosphate, and cetyltrimethylammonium bromide, can better disperse asphaltene aggregations. The results also revealed that the role of anions such as iodide, and hexafluorophosphate in the dispersion of asphaltene aggregates is more important than cations. In addition, the results showed that except for tetramethylammonium bromide, the efficiency of the salts was increased with increasing concentration.     

Modeling the effectiveness of oil combating from an ecological perspective--a Bayesian network for the Gulf of Finland; the Baltic Sea

Maritime traffic poses a major threat to marine ecosystems in the form of oil spills. The Gulf of Finland, the easternmost part of the Baltic Sea, has witnessed a rapid increase in oil transportation during the last 15 years. Should a spill occur, the negative ecological impacts may be reduced by oil combating, the effectiveness of which is, however, strongly dependent on prevailing environmental conditions and available technical resources. This poses increased uncertainty related to ecological consequences of future spills. We developed a probabilistic Bayesian network model that can be used to assess the effectiveness of different oil combating strategies in minimizing the negative effects of oil on six species living in the Gulf of Finland. The model can be used for creating different accident scenarios and assessing the performance of various oil combating actions under uncertainty, which enables its use as a supportive tool in decision-making. While the model is confined to the western Gulf of Finland, the methodology is adaptable to other marine areas facing similar risks and challenges related to oil spills.     

Influence of the acid–basic character of oxide surfaces in dispersants effectiveness

Physical–chemical surface character has been described as a determinant factor in adsorbing polyelectrolytes onto oxide surfaces. Since basically composed by hydroxyl groups, the acidity or basicity induced by the bulk lattice in such groups seems to be of great relevance in the adsorption process. The influence of such properties in the adsorption of polyacrylic acid derivated polymers onto SnO₂ and Al₂O₃ surfaces is, therefore, studied in this paper. Polyacrylate acid molecules are observed to hardly adsorb onto the SnO₂ surface but strongly adsorb, as reported previously, onto the alumina surface. This behavior is explained based on the pronounced difference in relation to the acidity of both surfaces and, in this sphere of thought, a basic polymer (Chitosan; CS) is discussed as a functional dispersant for powders with acid surface character, such as SnO₂. Zeta potential measurements showed that this polymer raises the SnO₂ potential to +30 mV without pH variations.     

Discussion of silica speciation, fouling, control and maximum reduction

In the production of ultrapure water for the power and microelectronics industries, multiple pass reverse osmosis (RO) process is commonly the major step in the reduction of dissolved and suspended matter before polishing by ion exchange and other methods to attain the high purity requirements. With the diverse location of power plants and microelectronic manufacturing facilities around the world, silica concentrations in source waters can range between 1 and 60 ppm (mg/L) to even 300 ppm in some volcanic regions. High pressure steam generators and fine microelectronic structures now require water containing less than 1 ppb (ug/L) concentrations of silica. In designing purification processes, silica has presented issues not only as formidable challenges in many locations as RO membrane foulants, as well as a contaminant requiring efficient removal. Analyses of RO membrane foulants and correlation with water chemistry in the course of trouble-shooting numerous RO processes continues to offer us opportunities to understand silica chemistry, the patterns of silica fouling and methods by which we can chemically control the RO process. Such understanding is applicable to the operation of ion-exchange resin beds as well. In this paper we review the speciation of silica in feedwaters, and chemical approaches to controlling fouling and maximizing silica reduction. Silica and silicates are addressed in the three categories of reactive soluble, non-reactive soluble (colloidal, not filterable) and non-reactive insoluble (particulate, filterable) forms. A brief review of geochemistry, the chemical and biochemical dissolution and deposition of silica and silicates in nature is provided for insights and understanding of natural processes that can be applied to the task of process design and control in silica removal from water.     

几种油井水泥外加剂的作用机理

本文综述了近年来国内外在油井水泥速凝剂、缓凝剂、分散剂和降失水剂作用机理研究方面的新进展.     

Effect of Pour Point Depressants Combined with Dispersants on the Cold Flow Properties of Biodiesel-Diesel Blends

Poor cold flow property is a major issue that hinders the application of biodiesel-diesel blends. In this work, a series of methacrylate-benzyl methacrylate-N-vinyl-2-pyrrolidone terpolymers (RMC-MB-NVP, R = C₁₂, C₁₄, C₁₆, C₁₈) was synthesized and used as the pour point depressants (PPD) for waste cooking oil biodiesel blends. To further improve their depressive effects, dispersants, including Tween (40, 60, and 80), Span (40, 60, and 80), phthalic acid esters (PAE), and fatty alcohol polyoxyethylene ether (FAPE; FAPE 5, FAPE 7, and FAPE 9), were optimized and combined with the C₁₄MC-MB-NVP terpolymers. The effects of C₁₄MC-MB-NVP terpolymers and combined PPD (PPDC) on the cloud point (CP), cold filter-plugging point (CFPP), and pour point (PP) of biodiesel blends were studied. Here, results showed that the presence of dispersants can efficiently enhance the solubility and dispersibility of polymeric PPD in biodiesel blends; thus, the PPDC presents better depressive effects. Among them, C₁₆MC-MB-NVP (5:1:1) combined with FAPE 7 dispersant at 4:1 mass ratio (PPDC-FAPE 7) showed the best synergistic effect, and the CP, CFPP, and PP of B20 treated with 2000 ppm PPDC-FAPE 7 decreased by 4, 10, and 19 °C, respectively. Moreover, differential scanning calorimetry, polarizing optical microscope, and rheological analyses were performed to rationalize the action mechanism of these PPD and dispersants in biodiesel blends.     

Use of novel polyetheralkanolamine comb polymers as pigment dispersants for aqueous coating systems

The adsorption of a series of polyetheralkanolamine comb polymers characterized by a different length of the hydrophilic tail has been investigated at the carbon black/water interface by measuring adsorption isotherm, contact angle, wetting rate, zeta potential, and particle size distribution. Zeta potential measurements and adsorption layer thickness results suggest that polyetheralkanolamines with high ethylene oxide (EO) content provide only steric stabilization and they adsorb at the interface with the ethylene oxide chains in a coil conformation. The thickness of the adsorbed layer increases with increasing EO units; however, the surface tension and interfacial tension decrease with increasing EO content. Adsorption isotherms show that most of the added polyetheralkanolamine adsorbs onto the carbon black and only a small amount stays in the water phase. When treated with a polyetheralkanolamine, carbon black dispersions show uniform (unimodal) and narrow particle size distribution with very small median sizes of about 0.10 μm. The pigment concentrates containing the polyetheralkanolamine show excellent color compatibility in various decorative commercial white paints containing a wide range of resins and exhibit low viscosity with nearly Newtonian flow behavior. Presented at the 2006 FutureCoat! Conference, sponsored by the Federation of Societies for Coatings Technology, in New Orleans, LA, on November 1–3, 2006.     

当前值得开发的纺织印染助剂

讨论了若干值得开发的纺织印染助剂,如染料分散剂、渗透剂、氧化剂、染料沉淀防止剂、超细纤维染色助剂等.