Characterization of Water/Sucrose Laurate/n-Propanol/Allylbenzene Microemulsions

Water/n-propanol/sucrose laurate/allylbenzene micellar systems were formulated and applied in the isomerization of allylbenzene in the presence of heterogenized derivatives of some platinum group catalysts. The ratio (w/w) of n-propanol/surfactant studied herewith was 2/1. Temperature insensitive microemulsions were found. The microemulsions were characterized by the volumetric parameters, density, excess volume, ultrasonic velocity, and isentropic compressibility. The densities increase with increases in the water volume fraction. Excess volumes of the microemulsions decrease for water volume fractions below 0.2, level off for water volume fractions between 0.2 and 0.6 then increase for water volume fractions above 0.6. Excess volumes of the studied micellar systems increase with temperature. Isentropic compressibilities increase with temperature for water volume fractions below 0.8 and decrease for water volume fractions above 0.8. Structural transitions from water-in-oil to bicontinuous to oil-in-water occur along the microemulsion phase. The particle hydrodynamic diameter of the oil-in-water microemulsions at the 0.95 water volume fraction was found to decrease with temperature.     

Carboxylate surfactant systems exhibiting phase behavior suitable for enhanced oil recovery

A large variety of aliphatic and aromatic carboxylate surfactants with alcohols as cosurfactants displayed phase behavior with n-decane that indicated they could be useful in enhanced oil recovery. Three-phase systems with large volume fraction middle-phase microemulsions were observed with sodium isostearate and sodium oleate. The interfacial tension between top and bottom phases was at a minimum (∼0.001 dyne/cm) at the optimal salinity where the uptake of oil and water in the middle phase was equal. The phase behavior of carboxylates was affected by pH and added bases. In cases where a bicarbonate-carbonate buffer was used to control pH, the optimal salinity decreased as the pH decreased. Use of ethoxylated alcohols as cosurfactants increased optimal salinities markedly and caused formation of very large volume fraction middle phases. Neutralized tall oils and tall oil fatty acids with alcohols as cosurfactants gave 3-phase behavior with n-decane with large volume fraction middle-phase microemulsions.     

乳状液和微乳液体系的形成及其性能研究

以柴油／水、汽油／水、煤油／水为实验体系,制备了乳状液和微乳液并对其性能进行了系统的研究。结果表明：乳状液的粘度是分散相体积分数和粒径的函数并获得了相应的关联式;影响乳状液稳定性的主要因素是乳状液的粒径而不是粘度;在微乳液体系中,表面活性剂的用量和分散相体积之间存在着比例关系;微乳液的形成只与它本身的组成有关而与制备方法无关。     

Formation and investigation of microemulsions based on jojoba oil and nonionic surfactants

The properties of jojoba oil make it uniquely suited as a raw material for the cosmetics industry. Water-based, thermodynamically stable preparations of jojoba oil are essential in many formulations. New microemulsions were prepared based on jojoba oil and different nonionic surfactants, namely polyoxyethylene-(ethylene oxide)₁₀-oleyl alcohol (Brij 96V) and ethoxylated sorbitan esters (Tweens). The effects of the surfactants and of primary alcohols as cosurfactants on the isotropic regions of the phase diagram were elucidated. It was found that, up to a certain cosurfactant chain length, the isotropic region expanded considerably as chain length increased. The size of the isotropic region also increased as a function of the ethylene glycol content of the aqueous phase in microemulsions based on ethoxylated alcohol but shrank when ethylene glycol was included in microemulsions prepared with ethoxylated sorbitan esters. Secondary structural phase transitions from water-in-oil to bicontinous and to oil-in-water structures (as determined by measuring conductivity and viscosity) were found to be related to jojoba oil content. Dynamic light scattering and small angle X-ray scattering studies established that incorporation of jojoba oil into Brij 96V micelles caused micellar transformation from elongated to spherical droplets and a decrease in the aggregation number.     

Triton X-100/正构醇/石油醚/水反相微乳液性质的研究

通过测定微乳液的电导率值,确定配制W/O型Triton X-100/正构醇/石油醚/水微乳液的最大增溶水量;根据微乳液含水量与电导率关系曲线及体系的拟三元相图,讨论了正构醇种类、正构醇含量、乳化剂与油相质量比对W/O型微乳液的结构、电导率、增溶水量的影响。结果表明:乳化剂与油相质量比大于1时,正戊醇、正己醇和正庚醇为助剂配制的Triton X-100/正构醇/石油醚/水体系微乳液有较大的增溶水量,而乳化剂与油相质量比大于1.5时,以正丁醇为助剂配制的Triton X-100/正构醇/石油醚/水体系微乳液才有较大的增溶水量;正构醇的链长及加入量影响微液滴界面膜的强度,从而影响微乳液的增溶水量、电导率及微乳液形成区域的大小;对于Triton X-100/正构醇/石油醚/水体系,正戊醇是形成W/O型微乳液的较好助剂,当正戊醇与Triton X-100的质量比为0.5时,W/O型微乳液的形成区域最大。     

Water Solubilization Using Nonionic Surfactants from Renewable Sources in Microemulsion Systems

In this study the effect of temperature, NaCl and oils (hydrocarbons: C(8)-C(16)) on the formation and solubilization capacity of the systems of oil/monoacylglycerols (MAG):ethoxylated fatty alcohols (CEO(20))/propylene glycol (PG)/water was investigated. The effects of the surfactant mixture on the phase behavior and the concentration of water or oil in the systems were studied at three temperatures (50, 55, 60?°C) and with varied NaCl solutions (0.5; 2; 11%). Electrical conductivity measurement, FTIR spectroscopy and the DSC method were applied to determine the structure and type of the microemulsions formed. The dimension of the microemulsion droplets was characterized by dynamic light scattering. It has been stated that the concentration of CEO(20) has a strong influence on the shape and extent of the microemulsion areas. Addition of a nonionic surfactant to the mixture with MAG promotes an increase in the area of microemulsion formation in the phase diagrams, and these areas of isotropic region did not change considerably depending on the temperature, NaCl solution and oil type. It was found that, depending on the concentration of the surfactant mixture, it was possible to obtain U-type microemulsions with dispersed particles size distribution ranging from 25 to 50?nm and consisting of about 30-32% of the water phase in the systems. The conditions under which the microemulsion region was found (electrolyte and temperature-insensitive, comparatively low oil and surfactant concentration) could be highly useful in detergency.     

Preparation and characterization of platinum-ruthenium bimetallic nanoparticles using reverse microemulsions for fuel cell catalyst

Platinum-ruthenium bimetallic nanoparticles are prepared by chemical reduction using sodium borohydride in reverse microemulsions of water/isooctane/Igepal CA-630/2-propanol for fuel cell catalysts. The prepared nanoparticles are characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray analysis. The average size and morphology of nanoparticles are dependent on the water volume fraction in reverse microemulsion system in the range of ca. 2-4 nm. The morphology of particles is related with the percolation behavior of water droplets in reverse microemulsions. By the pretreatment of water phase using a hydrochloric acid, the particles of a homogeneous solid solution state can be obtained. The CO stripping cyclovoltammetry and the electrochemical measurements compared with commercial catalyst show that the prepared particles have a high electrochemically active surface area and a stable and high catalytic activity for reformate gas oxidation.     

Gas mass transfer to AOT-based microemulsions

The present paper analyses the gas/liquid mass transfer process employing carbon dioxide as gas phase and ternary water in oil microemulsions as absorbent liquid phases. The liquid phases were obtained by a direct mixing of water, 2,2,4-trimethylpentane and sodium bis(2-ethylhexyl)sulfosuccinate (Aerosol OT). The characteristics of the microemulsions employed as liquid phase have been analysed to interpret the experimental results observed in the absorption process. More specifically, they have been analysed in relation to the percolation phenomenon and the effects produced by this phenomenon upon the different physical properties. Characteristic results have been observed for the gas/liquid mass transfer using microemulsions, because ternary microemulsions with high viscosity values in relation to pure water show a faster absorption process than the carbon dioxide/water system. This characteristic behaviour has been explained on the basis of the microemulsions internal dynamics.     

Foaming Properties of Commercial Lauramide Amide Oxide in High‐Salinity Water

The original purpose of our work was finding commercial foaming agents for high‐salinity reservoirs. During the study, the commercial lauramide amide oxide solution displayed different foaming properties in high‐salinity water (salinity 220,000 mg/L) at different aging times and relatively low temperature (25 °C). Foam volume decreases drastically first with the increase of aging time. Then, with further aging, foam volume increases. However, in low‐salinity water or at high temperature, no obvious foam volume variation was observed. Lauric acid in the commercial surfactant plays a key role. Under proper temperature and pH conditions, lauric acid will react with Ca²⁺. Calcium laurate generated from lauric acid in the commercial form and Ca²⁺ from water influences the foaming property significantly. At the beginning of calcium laurate generation, surfactants adsorb on calcium laurate and decelerate the diffusion velocity of lauramide amide oxide from the bulk phase to the air–water interface. With the increase of aging time, calcium laurate gathers, thus adsorption of lauramide amide oxide by calcium laurate decreases. Hence, the foaming volume increases.     

Effect of Alkyl Sulfate on the Phase Behavior of Microemulsions Stabilized with Monoacylglycerols

In this study the effect of an anionic surfactant (sodium dodecyl sulfate SDS) and oils (hydrocarbons: C12–C16) on the formation and phase behavior of the systems of oil/monoacylglycerols (MAG):SDS/propylene glycol/water has been investigated. The effects of the surfactant mixture on the phase behavior and the concentration of water or oil in the systems were studied at three temperatures (50, 55, 60 °C). Electrical conductivity measurement, FT-IR spectroscopy and differential scanning calorimetry methods were applied to determine the structure and type of the microemulsions formed. The dimension of microemulsion droplets was characterized by dynamic light scattering. It has been stated that the concentration of SDS has a strong influence on the shape and extent of the microemulsion areas. Addition of an ionic surfactant to the mixture with MAG promotes an increase in the area of microemulsion formation in the phase diagrams, and these areas of the isotropic region change with the temperature. It was shown that the presence in the systems of a surfactant more hydrophilic than MAG caused an increase in water content in the microemulsions. It was found that, depending on temperature and concentration of the surfactant mixture, it was possible to obtain a W/O type microemulsion with a dispersed particles size distribution ranging from 20 to 50 nm and containing about 17–38% water in the system. Among different alkanes (from C12 to C16), hexadecane embedded microemulsions showed a maximum water solubilization capacity.     

The Irritant Effects of Pharmaceutically Applied Surfactants

Dermal or transdermal medication may lead to irritant contact dermatitis. However, little information is available on the irritant effect of surfactants which are applied in topical formulations. Our aim was to examine the irritant effect of the most frequent compounds in topical products. A murine model was applied. The following compounds were examined: sodium lauryl sulphate (SLS), polyethoxylated (40EO) hydrogenated castor oil and sucrose laurate. SLS led to severe erythema, increase in transepidermal water loss (TEWL) and induced necrosis and accumulation of neutrophylic granulocytes and lymphocytes. Exposure to sucrose laurate resulted in an elevation of TEWL, but histology did not reveal impairment of the skin structure. Application of polyethoxylated (40EO) hydrogenated castor oil was not accompanied by tissue damage. Special attention should be paid to the irritant effect of SLS. Polyethoxylated (40EO) hydrogenated castor oil seems to be a non-irritant agent and sucrose laurate is also a promising candidate for application in topical preparations.     

混凝土界面渗流的集料体积率阈值算法及其影响因素评价

提出了混凝土界面渗流的集料体积率阈值算法并定量评价了影响该阈值的因素.通过引入周期性边界条件,在立方体单元内模拟混凝土中集料和界面的分布.基于模拟的混凝土细观结构,给出了集料体积率阈值算法并讨论了模拟单元边长对界面渗流概率的影响,在该算法的有效性获得实验验证后,定量评价了界面厚度、最大集料直径和集料级配对集料体积率阈值的影响.结果表明:集料体积率阈值随着界面厚度的增大而减小,但随着最大集料直径的增大而增大;集料级配对集料体积率阈值有很大的影响,其影响程度在20%左右,最大集料直径对集料体积率阈值的影响仅为7%.     

水平管内水环输送模拟稠油减阻特性

基于自主设计加工并搭建的水环输送稠油减阻模拟管路系统,采用500^#白油模拟稠油,试验研究了稠油在水环作用下的水平管流阻力特性,分析了油相表观流速（0.3～1.0m/s）、水相表观流速（0.11～0.72m/s）及入口含水率（0.13～0.49）对水润滑管流流型特征及减阻效果的影响。结果表明：环状水膜可有效隔离并润滑油壁界面,油-水两相流流型总体上呈稳定的偏心环状流结构;水环输送可大幅降低管道输送过程中的压降,其压降值仅为相同油流量下纯油输送压降的1/55～1/27;当入口含水率为0.13～0.27时,水环输送的效能显著,输油效率均高于40;油相表观流速和入口含水率的增加会增大单位管长压降,降低水环输送的减阻效果和输油效能。     

Dynamic behaviour of drops in oil/water/oil dispersions

The dynamic behaviour of drops of oil/water/oil (O/W/O) and water/oil (W/O) in abnormal polymer/water/surfactant systems was investigated. The size of internal oil droplets continuously decreased with time until it reached a steady-state value. Whereas the size of multiple water drops showed a minimum. After the minimum, the size of multiple water drops either reached a steady-state value or continued enlarging until phase inversion occurred. The phase inversion occurred because inclusion of oil droplets into water drops resulted in a continuous increase in effective volume fraction of dispersed phase. The time evolution of the size of multiple drops was described in terms of a balance between (a) drop break-up and escape and (b) drop coalescence and inclusion. The inclusion events retarded the initial decrease in the size of multiple water drops with time and increased the drop size after the minimum. By reducing the surfactant concentration, the ability of the dispersed phase to entrain the continuous phase decreased so that no minimum was achieved for the size of multiple drops with time, similar to conventional systems with simple drops. The size distribution of the multiple water drops initially narrowed and then widened again, whereas the size distribution of internal oil droplets continuously narrowed with time until it reached a constant value. Generally, the size distribution of drops narrowed as the average size of drops decreased. The possible mechanisms for complex drop formation were discussed and drop deformation was suggested as the main cause for inclusion at a low dispersed phase ratio.     

Reactant partitioning in free-radical heterophase polymerization: The case of inverse microemulsion polymerization of acrylamide

Conversion curves have been determined at 60°C for the polymerization of acrylamide in percolating inverse microemulsions. Ammonium peroxo-disulphate (APS) and dibenzoyl peroxide (DBP) were used as initiators of free-radical polymerization in the presence or absence of potassium nitrosodisulphonate (Fremy's salt, FS). The percolation decreases the rate of polymerization of acrylamide initiated by APS. The polymerization is inhibited by FS. After an inhibition period, retardation of acrylamide polymerization is more pronounced in non-percolating microemulsions. No inhibition periods were observed for DBP-initiated polymerization of acrylamide. The percolation shortens the time interval of the ‘slow’ polymerization of acrylamide, but the rates of rapid acrylamide polymerization above 10% conversion are the same for percolating and for non-percolating inverse microemulsions. The polymer particle diameter is a function of acrylamide/water weight ratio and of [water]/[AOT] (AOT: bis(2-ethylhexyl)-sulphosuccinate sodium salt) molar ratio. No effect of the initiator's nature either in the presence or in the absence of FS was found. The results are interpreted on the basis of initiator and/or nitroxide radical partitioning between oil and water phases of the inverse microemulsion, and are discussed with respect to the mechanism of acrylamide polymerization and polymer particle formation proposed for non-percolating inverse microemulsions.     

Prediction of water and oil percolation thresholds of a microemulsion by modeling of dynamic viscosity using response surface methodology

This paper presents the application of Design of Experiments to predict water and oil percolation thresholds of a microemulsion using dynamic viscosity data as a function of water volume fraction. One-factor and historical data were the two investigated design types of response surface methodology. The models were validated and maximized. The predicted water and oil percolation thresholds using historical data design were close to their experimental values. The oil percolation threshold could be predicted more precisely using one-factor design than historical data design while one-factor design can capture the relationship between the response and design factor with fewer experimental data.     

镀银镍粉/硅橡胶高导电复合材料的制备及性能研究

研究镀银镍粉体积分数对镀银镍粉/硅橡胶高导电复合材料性能的影响。结果表明:随着镀银镍粉体积分数增大,复合材料的邵尔A型硬度增大,拉断伸长率快速减小,体积电阻率减小并出现明显逾渗现象;当镀银镍粉体积分数为0.44时,复合材料具有良好的导电稳定性和优异的电磁屏蔽效能,但耐电化学腐蚀性能较差。     

制备纳米BaSO4的W/O微乳液体系组成及稳定性

以TritonX 10 0 正己醇 环己烷 水制成W O微乳反胶团体系 ,通过测定体系的电导率和观察液晶相的出现确定相点绘制了各体系的拟三元相图 ,研究了温度、盐浓度和油相组分对W O微乳液体系稳定性的影响 .实验发现助表面活性剂与表面活性剂的配比对微乳液的稳定性有显著影响 .随着温度的升高 ,W O微乳液稳定区域减小 ,可通过升高温度对微乳液进行破乳 ;与以纯环己烷为油相的体系相比 ,油相中含有少量正己烷的体系具有更优异的性质 .所得结果为利用该W O微乳液体系制备纳米颗粒提供了基础数据     

柴油微乳液的制备及其性能研究

介绍了-10<'#>,0<'#>柴油微乳液的组成,确定了柴油、水、表面活性剂的质量配比,采用超声波处理为分散手段制备了微乳化柴油;并将-10<'#>柴油制备的微乳液与0<'#>柴油制备的微乳液作了对比;对制得的微乳化柴油的十六烷值、闪点、密度、黏度、粒径、凝点、热值、胶质质量浓度等理化性能指标进行了测定与分析对比;同时...     

柴油微乳液拟三元相图的研究

绘制了复合表面活性剂(D0821/Tx-4/AEO-3)/正戊醇/柴油/水体系在不同温度及不同正戊醇质量分数时的一系列拟三元相图。结果表明,正戊醇质量分数及温度对拟三元相图及水最大增溶量有很大影响,醇量太大或太小形成的微乳区面积均较小;温度升高,微乳区面积及水最大增溶量也大大减少;随着正戊醇质量分数的增大,每一个温度下的微乳区及其最大增溶水量都逐渐向AEO-3/正戊醇/油角漂移。