Aqueous Processing and Stabilization of Manganese Zinc Ferrite Powders via a Passivation–Dispersion Approach

A dispersion scheme for aqueous processing of manganese zinc ferrite suspensions is presented. The addition of oxalic acid leads to the formation of a uniform negative charge on the surface such that a cationic polyelectrolyte, polyethyleneimine (PEI), adsorbs and provides electrosteric dispersion. At 0.5 w/w (weight percent with respect to the dry powder) oxalic acid addition, there is a relatively uniform negative surface charge (approximately −30 mV) within the suspension pH range investigated (3–10), eliminating the isoelectric point (pH ∼7.6) present for the as-received metal oxide powder. At the addition of 0.5 w/w PEI on an oxalate-treated surface, the surface charge is constant and positive (∼20 mV) through a wide pH range, ∼5–10. The resulting rheological data for passivation–dispersion of relatively high-solids manganese zinc ferrite suspensions (∼80 wt%) demonstrate improved colloid stability with improved rheological properties. The resulting apparent viscosity and Bingham yield point is 0.01 Pa·s (12.0 cP) and 0.24 Pa (2.4 dynes/cm²), respectively. A sulfonated napthalene-based dispersant, typically used in industry, gives an apparent viscosity and Bingham yield point of 0.03 Pa·s (32 cP) and 3.1 Pa (31 dynes/cm²), respectively.     

Study the Influence of Some Polymeric Additives as Viscosity Index Improvers,Pour Point Depressants and Dispersants for Lube Oil

Abstract

In the present work, some polymeric additives were prepared as pour point depressants, viscosity index improvers and dispersant additives for lube oil, these additives prepared by copolymerization of maleic anhydride with different esters of acrylic acids and then amination. The molecular weights of the prepared copolymers were determined by gel permeation chromatograph (GPC). The efficiency of the prepared compounds as pour point depressants and viscosity index improvers was investigated. It was found that the efficiency of the prepared compounds as pour point depressants increases with decreasing the concentration of the prepared polymers, increasing the chain length of alkyl groups and increases with decreasing the molecular weight. The efficiency of the prepared compounds as viscosity index improvers increases by increasing the concentration of these additives and by increasing the molecular weight of polymer. It was found that the amination of polymer enhance the efficiency of the prepared additives as pour point, viscosity index, and dispersant for sludge.     

Synthesis and Evaluation of Detergent/Dispersant Additives from Polyisobutylene Succinimides

Lube oil additives are essential for all types of lubricating oils; they are added either to give the oils new properties as detergency and oxidation stability or to improve such properties as pour point and viscosity index. They are added at varying proportions to meet the performance requirements. The present work is concerned with studying of detergent/dispersant type additives based on synthesized polyisobutylene succinic anhydride (PIBSA) and its aminated compounds (PIBSA) with different types of polyethylene polyamine such as ethylene diamine, diethylene Triamine, Triethylene tetramine, and tetraethylene pentamine. Different types of polyisobutylene succinimides were reacted with dodecylphenol and formaldehyde to prepare different type of Mannish bases. The efficiency of the prepared compounds as antioxidants and detergents/dispersants was investigated. It was found that compound D₁ (Mannich base IV) is the best antioxidant additive for lube oil, and all the prepared compounds have excellent dispersancy power.     

纳米粉体的分散性研究及在电触头材料制备中的应用

介绍了纳米电触头材料的制备工艺。采用不同的分散方法,如:物理分散法(超声波法、机械分散法)、化学分散法和聚电解质分散,可以获得理想的分散效果。探讨了纳米粉体的分散作用的机制和纳米电触头材料在研究与应用上的优越性以及存在的问题。     

染料分散剂新原料-高沸醇木质素的研制

采用1，4-丁二醇水溶液为溶剂的高沸醇溶剂法，从松木，杉木，稻草等原料制备纤维素与高沸醇木质素。使用上述原料，在70%-90%1，4-丁二醇水溶液中添加少量催化剂。并在190℃-220℃条件下蒸煮1-3小时后，分离反应产物，得到固体纤维素与高沸醇木质素-丁二醇溶液，不溶于水的高沸醇木质素通过加水沉淀的方法。从反应后的液体混合物中分离。高沸醇木质素具有较高的反应活性。灰分含量很低。适于制备新型染料分散剂，有广泛应用前景。     

纳米ZrO2-8％Y2O3水相悬浮液分散稳定性研究

目的 探究Y2O3为8％的纳米ZrO2-8Y2O3(8YSZ)水相悬浮液的分散机理.方法 选用PAA、PEG600、PEG2000三种不同分散剂,在不同分散剂含量和pH值条件下,制备固相含量(以质量分数计)为20％的纳米8YSZ水相悬浮液.采用Zeta电位、粒度分布和悬浮液黏度对纳米8YSZ水相悬浮液的分散稳定性进行表征.结果 pH为中性时,悬浮液中分散剂PAA、PEG2000、PEG600的最佳用量(以质量分数计)分别为2.4％、2.4％、3.2％,对应的最低黏度分别为4.08、3.84、3.36 mPa·s.加入分散剂PAA后,纳米8YSZ等电点的pH值由6左移到4附近.当PH值为8时,纳米8YSZ颗粒的Zeta电位最高,达–44.5 mV.结论 纳米8YSZ水相悬浮液的分散稳定性与分散剂的种类、含量和pH值有关.仅添加分散剂或调节pH值均不能使纳米8YSZ水相悬浮液分散稳定.分散剂PAA同时具有静电稳定和空间位阻稳定的作用.分散剂的总体分散效果由高到低依次为PAA、PEG2000、PEG600.制备固相含量为20％的纳米8YSZ水相悬浮液的最佳条件为:pH=8,PAA含量为2.4％.此时悬浮液的分散效果最好,黏度最低,为2.56 mPa·s.     

Dispersion of aluminum‐doped zinc oxide nanopowder in non‐aqueous suspensions

This study proposes appropriate dispersants for dispersing aluminum‐doped zinc oxide (AZO) nanopowder in the commonly used organic solvent‐dimethylacetamide (DMAC). The dispersion efficiencies and stabilization mechanisms of four DMAC‐soluble dispersants, poly(acrylic acid) (PAA), polyethyleneimine (PEI), poly(vinyl alcohol) (PVA), and poly(vinyl pyrrolidone) (PVP), are compared. The non‐polyelectrolyte‐based PVA and PVP surprisingly exhibit greater efficiency than the polyelectrolyte‐based PAA and PEI. This is because the nano AZO is soft‐agglomerated in DMAC and easily de‐agglomerated by the application of ultrasonic power; therefore, the increased viscosity contributed from additions of PVA and PVP efficiently prevent reagglomeration and sedimentation of the nanopowder. This stabilization mechanism is evidenced by an experimental analysis of zeta potentials and rheology and also by theoretical calculations based on Stokes’ law.     

Multifunctional Additives Viscosity Index Improvers,Pour Point Depressants and Dispersants for Lube Oil

Abstract

In the present work, some polymeric additives based on styrene-maleic anhydride copolymer were prepared and evaluated as multifunction lube oil additives (viscosity index improvers, pour point depressants, and detergent-dispersant additives). The styrene-maleic anhydride copolymer reacted with different alcohols (dodecyl alcohol, hexadecyl alcohol, octadecyl alcohol, and docosanol) to prepare four different types of esters and aminated with different types of amines (dodecyl amine, hexadecyl amine, and octadecyl amine) to prepare another three co-polymeric additives. Structure of the prepared compounds was confirmed by I.R. spectroscopy. The molecular weights of the prepared copolymers were determined by using gel permeation chromatograph and the percentage of esterification and amination were determined by ¹HNMR. The efficiencies of the prepared compounds as viscosity index improvers, pour point depressants, and detergents-dispersants were investigated. It was found that the efficiency of the prepared compound as viscosity index improvers increases with increasing the concentration of additives in the solution and with increasing the molecular weight of prepared compounds, while the efficiency of the prepared compounds as pour point depressants increases with decreasing the concentration of the prepared polymers. On the other hand, the prepared compounds showed excellent dispersion power.     

Inhibition of Accumulation of Crude Petroleum Storage Tank Bottom Sludge by Using Polymer Dispersants

The study was focused on evaluation of a novel approach for minimizing accumulation of tank bottom sludge during bulk storage of crude oil by using polymer dispersants. Fraction of basic sediments and water remaining in crude oil over a period of 6 months was monitored to assess the effect of additives on extent of settling. At a dose of 100 mg/L, accumulated sludge at the bottom of the container was lower by 20.5 and 22.5 times in the presence carboxymethyl cellulose and polyacrylate, respectively, than in samples without any dispersant. Further, the mechanism behind enhanced stability was investigated through viscosity, particle size, and zeta potential measurements.     

Synthesis of Some Oil Spill Dispersants From Locally Alkyl Benzene and Evaluating Their Dispersion Efficiency and Toxicity

Seven surface-active agents used as oil spill dispersants were prepared based on linear alkyl benzene-N-hydroxyl ethyl sulfonamide. Five of them are nonionic and the other two are ionic. These surfactants were prepared from locally raw materials. Their chemical structure and surface-active properties were investigated using the FT-IR, surface tension, and interfacial tension measurements. The efficiency of these dispersants was compared with a commercial used dispersant from Dasic Company. The toxicity test was carried out using aquatic animal (Modiolus adriaticus). The animal was exposed to these dispersants for 120 h at different dispersant to oil ratio. From the obtained results it was found that, the percentage of mortality of mussels after 1-h exposure from the start of the tests equalized zero. It varied with passing time up to 120 h, at which the mortality rate became 50%.