WATER TRANSFER BETWEEN WATER AND WATER+NaCl DROPLETS IN EMULSIONS

Water transfer between water droplets and water + NaCl droplets dispersed within emulsions have been pointed out by differential scanning calorimetry. Using a solution- diffusion model, water fluxes have been calculated.     

DEMULSIFICATION OF WATER IN OIL EMULSIONS USING WATER SOLUBLE DEMULSIFIERS

The possibility of using a water soluble,as opposed to the conventional oil soluble demulsifier, to destabilize a w/o emulsion in crude oil has been explored. It was found experimentally that a surfactant soluble in the water (dispersed) phase could destabilize the emulsion. Polymer molecules with varying HLB's and molecular weights and structure were synthesized and these compounds were added to the water phase to destabilize the water/crude oil emulsions. Molecules with a high percentage of hydrophilic groups and low molecular weights showed very good demulsifying abilities.     

EFFECTS OF INTERFACIAL POLYUREA FILM ON THE STABILITY OF OIL IN WATER EMULSIONS

The stability of oil in water emulsions containing a triisocyanate soluble in the oil phase was investigated. The oil component was either di-n-butyl phthalate (DBP) or a mixture of DBP with liquid paraffin. The time required for the average size parameter to reach a constant value was studied. It was found that the polyurea film produced by an interfacial polymerization reaction between water and a triisocyanate contributed to make the stable emulsions. The effects of drop size, temperature, polarity of oil phase, triisocyanate concentration, and mechanical stirring on the stability of the emulsions were established in this study. The film thickness at the point where the average size parameter reached a constant value was found to be of the order of 0. 002 ～ 0. 004μ.     

FRAGMENTATION OF PRIMARY FLOCS IN EMULSIONS AND THE SUBSEQUENT REDUCTION OF COALESCENCE

In existing theories emulsion desiabilization is considered as the combined processes of irreversible flocculation and coalescence of dispersed droplets. This approach can be justified when the potential pit characterizing the energy of droplet interaction is sufficiently deep, i.e. excluding small droplet dimensions, strong electrosiatic repulsion and low electrolyte concentrations. For smaller droplet dimensions and stronger electrostatic repulsions the emulsion instability must be considered as a combined process of reversible flocculation and coalescence. In this paper a mathematical model that couples the kinetics of flocculation, coalescence and floe fragmentation is developed in order to quantify the kinetic instability of emulsions with charged submicron droplets. The characteristic limes for flocculation (Smoluchowski's time τ_c) for coalescence (coalescence time τ_c) and for disaggregation (doublet lifetimeτ_d) are considered model parameters. The mathematical model applies to the case when and τ_d<< τ_c, which corresponds to a situation with a small multiplet concentration compared to the concentration of doublets and a singlet-doublet quasi-equilibrium. It is established that at singlet-doublet quasi-equilibrium the rate of the decline in the total droplet concentration is described by second order kinetics in distinction to the exponential time dependence valid for coalescence at irreversible flocculation. The double disintegration reduces the entire coalescence rate, expressed as τ_sm/ τ_d. This reduction is very large at small values of Td. The mathematical model presented can hased on the spontaneous disintegration of doublets predict changes in emulsion stability for model systems and also for technologically important emulsions.     

STABILITY OF WATER-IN-CRUDE OIL EMULSIONS: ROLE PLAYED BY THE STATE OF SOLVATION OF ASPHALTENES AND BY WAXES

The stability of water-in-crude oil (or model crude oil) emulsions was determined by means of separation/sedimentation tests and high voltage destabilization tests. First the impact of the state of solvation of asphaltencs on their ability to stabilize emulsions were studied. Secondly, we analyzed the role of naturally occurring waxes in the stabilization of emulsions. Finally, the emulsion stability when both asphaltenes and waxes are involved was investigated.     

STUDY OF DEMULSIFICATION OF WATER-IN-CRUDE OIL EMULSION

Demulsification of water-in-crude oil emulsion was studied at two different salinities, 0.5% and 10% sodium chloride, using five different nonionic surfactants. Equilibrium crude oil-water interfacial tension was measured with drop volume method. Low molecular weight surfactants were found to be completely ineffective as demulsifiers. Three surfactants which were effective demulsifiers, exhibited good interfacial activity, surface adsorption and surface pressure. The performance of the demulsifiers changed with change in salinity of aqueous phase. Surfactants effective as demulsifiers reduced surface tension of water by more than 25 dynes-cm^-1. For a given crude oil-water system, the surfactant which developed surface pressure in excess of 15 dynes-cm^-1 was found to be good demulsifier for that system. Based upon these studies, a physical model of demulsification has been proposed     

STABILITY OF HATER IN OIL EMULSIONS USING HIGH MOLECULAR WEIGHT EMULSIFIERS

Excellent stability of water-in-oil emulsions could be obtained by partial crosslinking of the fatty chain in several polyglycerol fatty esters. Such products were capable of emulsifying and stabilizing up to 50 wt% water in vegetable oils at a level of 3-5% emulsifier per total emulsion weight. The corresponding non-crosslinked products require at least 20-25% emulsifier to give the sane level of stability, with much higher viscosity.

Degree of polymerization, molecular weight distribution, viscosity, dielectric constant and refractive index of the emulsifier were correlated to the emulsion stability. The most remarkable result is a clear correlation between the molecular weight of the emulsifier and emulsion stability; best emulsions were prepared with polymeric emulsifier with MW of Ca. 40000.     

近临界水中聚丙烯腈无催化水解反应动力学

系统研究了近临界水中聚丙烯腈无催化水解反应动力学.在实验数据重现性和物料配比对PAN水解反应影响的考察基础上,系统测定了210～250℃下聚丙烯腈的水解反应动力学数据,采用元素分析仪、傅立叶变换红外光谱仪、热分析仪、凝胶色谱仪对水解产物进行了表征.结果表明,近临界水中聚丙烯腈无催化水解是可行的,其中温度与物料配比是影响水解速率的主要因素;通过控制不同水解条件,可得到不同含量的腈基(—CN)、酰胺基(—CONH2)和羧基(—COOH)二元或三元共聚物,产物侧基含量的不同有可能在不同的领域得到应用;以一级连串反应动力学模型对实验数据进行了拟合,得到了聚丙烯腈和聚丙烯酰胺水解反应活化能分别为53.37 kJ.mol-1和120.55 kJ.mol-1.     

FORMATION OF OIL IN GLYCEROIVWATER EMULSIONS: EFFECT OF SURFACTANT ETHYLENE OXIDE CONTENT

Oil-in-glycerol/water emulsions at various ratios of water to glycerol in the external phase were prepared with polyoxyethylated octylphenols and light mineral oil. As the water concentration in the external phase decreased, oil droplet size decreased down to a minimum size beyond which oil separation occurred. Also, the cloud points of various surfactants were depressed toward room temperature as the water content of the glycerol/water mixtures decreased. It was possible therefore to correlate the concentration of water needed for formation of the smallest droplets to the concentration of water needed for depression of the cloud point of each surfactant to room temperature.     

FORMULATION OF MODEL CUTTING-OIL WATER EMULSIONS USING PARAFFINIC OIL AND IONIC/NONIONIC SURFACTANT MIXTURE.

Cutting-oil emulsions are marketed under the shape of concentrates that the user has to dilute. More often these concentrates are monophasic microemulsions. We show that this kind of microemulsions may be obtained while relying on the generalized concept of Winsor, which guides the manipulation of three formulation parameters, which in turn rationally modify the surfactant interactions with the oily and the aqueous phases.

The model concentrates that we have formulated contain six constituents. The oily phase is constituted of paraffinic oil and normal decanol. The aqueous phase is a solution of monoethanolamine borate in water whose hardness is fixed at 40°f. The active mixture contains a hydrophilic surfactant and a lipophilic surfactant.

We have formulated concentrates presenting an excellent ability to dilution, a very good stability to the hardness of water and pHs in agreement with the cutting fluid specification sheets, while identifying the formulation parameters to the mass ratio of normal decanol in the oily phase, to the mass ratio of monoethanolainine borate in the aqueous phase and to the mass ratio of the hydrophilic surfactant in the active mixture.     

FREEZING OP WATER IN W/O EMULSIONS

A short review is given on the freezing of water in w/o emulsions. First the state of supercooled water is discussed. The quantitative treatment of the liquid-solid phase transition in supercooled water is given by the homogeneous nucleation theory. From the experimental methods, which are used to study supercooled water, only few are applicable to the liquid-solid phase transition. From these methods electron microscopy, thermal analysis and EFE are chosen to reveal some characteristic features of freezing of water in w/o emulsions. At the end of the paper the production of vitreous water by jet-freezing of w/o emulsions is reported. It is shown that especially the role of the surfactant molecules, which are necessary to stabilize emulsions with urn-sized droplets, is not understood in the liquid-solid transition. The possibility of reaching the homogeneous nucleation temperature of -40 C in w/o emulsions (and also the fact, that water can be vitrified in w/o emulsions using small cooling rates of 10¹² 10⁶ C/sec compared to the estimated necessary rate of 1012 C/sec), may not only oe caused by a statistical effect leading to the negligibility of heterogeneous nuclei, but also by some surfactant effects influencing the formation of homogeneous nuclei.     

非色散红外法在地表水油类测定中的应用

对非色散红外法应用于地表水油类测定的主要影响因素进行了探讨。指出使用该法在测定样品时如何采取正确处理方法，减少测量误差，并与紫外法测定结果作了比较。同时进行了方法论证。     

油品含水率的测量技术

介绍油品含水率测量的各种方法,如γ射线法、短波吸收法及微波法、电容法、射频法、红外光谱法、卡尔费休法,指出了这些方法的优、缺点。对我国含水率仪器仪表研制趋势进行了展望。     

STABILIZATION OPTIMIZATION OF AQUEOUS MONOMER SOLUTIONS IN OIL EMULSIONS USING THE COHESIVE ENERGY RATIO CONCEPT.

The Beerbower-Hill approach based on the Cohesive Energy Ratio concept (CER) has been applied in order to optimize the stabilization of Acrylamide-water or Acrylic Acid (pure and 80% neutralized)- water mixtures in cyclohexane emulsions.

Using surface tension measurements for the determination of the solubility parameter of the aqueous phase ( δ_w), it was found that the presence and amount of the water-soluble monomer could be accounted for the evaluation of the optimal HLB.

Predictions were compared to experimental HLB values obtained by using various blends of a low-HLB emulsifier (a sorbitan monooleate named MONTANE 80) and high-HLB emulsifiers (either a nonylphenolpolyoxyethylene [40 EO] or a pOE [20 EO] sorbitan trioleate, MONTANOX 85).     

航空润滑油中抗氧剂的热氧化动力学研究

模拟实际使用条件，对ВНИИНП-50-1-4Φ航空润滑油（以下简称50－1－4Φ润滑油）进行热氧化模拟试验，应用GC分析抗氧剂N－苯基－α萘胺（NPAN）的热氧化衰变程度。在50－1－4Φ润滑油热氧化衰变过程中，NPAN的热氧化反应表现为拟一级反应。补油可大大延缓NPAN的热氧化反应速率，不同的补油方式对NPAN的热氧化动力学也有显著影响。研究结果还表明粘度和总酸值不能有效反映润滑油的热氧化衰变程度。     

不完全相反转乳化过程分散相水滴形态发展研究

相反转乳化技术是制备高分子树脂水基分散体系的新方法[1～4].相反转指多组分体系(如油/水/乳化剂)中的连续相在一定条件下相互转化的过程,如在油/水/乳化剂体系中,其连续相由水相向油相(或从油相变为水相)的转变.在连续相转变区,体系的界面张力最低,因而分散相的尺寸最小.同理,可利用相反转技术直接将高分子树脂乳化为尺寸很小的水基微粒,即制备高分子树脂的水基分散体系.由于高分子树脂的粘弹性及相反转过程的复杂性,对高分子树脂的相反转乳化过程的机理研究较少.杨振忠[5]等通过调节高分子非离子型乳化剂浓度,可以有效地控制相反转完善程…     

COALESCENCE OF SECONDARY DISPERSIONS IN COMPOSITE PACKED BEDS

Oil water dispersions have been separated efficiently using composite beds made up of several materials. Selection of these materials was based on their wetting properties and fibre size. A bed composed of three layers: two fibre glass layers of different sizes followed by woven layer of polypropylene and stainless steel was found to give the best results.     

PREPARATION OF CLOUDY COCONUT OIL EMULSIONS CONTAINING DISPERSED Ti02 USING ATOMIZER

Food Grade Rutile TiO₂ was dispersed in coconut oil with the help of hydrophobic emulsifiers such as sorbitan esters and lecithin. The dispersed mixture was melted and blended with hydrophilic emulsifiers such as ethoxylated sorbitan esters and the preheated (60°C) blend was further sprayed by atomizer into cold water (20°C). The oil-in-water emulsions contained encapsulated TiO₂ in the internal phase. The technique is simple and allows preparation of stable emulsions with average droplet size of 1-10 microns.     

PREPARATION OF CLOUDY COCONUT OIL EMULSIONS CONTAINING DISPERSED TiO2 USING ATOMIZER

ABSTRACT

Food Grade Rutile TiO₂ was dispersed in coconut oil with the help of hydrophobic emulsifiers such as sorbitan esters and lecithin. The dispersed mixture was melted and blended with hydrophilic emulsifiers such as ethoxylated sorbitan esters and the preheated (60°C) blend was further sprayed by atomizer into cold water (20°C). The oil in water emulsions contained encapsulated TiO₂ in the internal phase. The technique is simple and allows preparation of stable emulsions with average droplets size of 1-10 microns.     

水溶性聚酯的热降解动力学研究

水溶性聚酯的热降解动力学研究应宗荣李瑞霞吴大诚（四川联合大学轻纺学院成都６１００６５）关键词水溶性聚酯，热降解，动力学，活化能高聚物的热稳定性直接影响高聚物的应用和加工成型．高聚物在高温时易发生热降解，导致分子链断裂，分子量降低，性能劣化．研究...