由表面活性物质溶液的动界面张力外推求平衡界面张力的研究

表面活性物质溶液的界面张力往往随时间而变,难以测得平衡界面张力J。Kloubek^[1]曾应用经验式:1/(δ_H2O-δ_t)=b/(At^1/2)+1/A,以[1/(δ_H2O-δ_t)]对1/t^1/2作图外推求得溶液的平衡表面张力,但所得结果仅与文献值大致相符。本文从理论上分析该经验式的由来,以及产生偏离的原因,并寻求了解决的办法。     

Temperature Dependence of the Surface Tension of Alkali Metals: A Unified Correlation

Abstract

In this work, new definitions of the normalized temperature and surface tension are proposed which result in a single plot for the surface tension of molten alkali metals. The functional dependence of the reduced surface tension on the reduced temperature can be adequately described by a straight line; the intercept and slope have been obtained using the linear regression approach. The method proposed herein predicts the values of surface tension at various temperatures with an average error of about 5%.     

The determination of interfacial tension by differential capillary rise

A method for directly determining interfacial tension without iteration from the difference in height between two capillaries is presented. An experimental technique is described for organic liquids both lighter and heavier than water, in which the menisci recede over surfaces wetted by the aqueous phase, thus providing the most favourable conditions for zero contact angle. The values determined experimentally using tables prepared from the known shapes of sessile interfaces agree well with accepted values of the interfacial tension.     

表面活性剂和四烷基溴化铵的复配：Ⅲ.四烷基溴化铵碳氢链长对 …

本文考察了四烷基溴化铵（ＴＡＡＢ）碳氢链长对离子型表面活性剂ＳＤＳ和ＤＴＡＢ在气／液表面吸附行为的影响。实验结果表明：与表面活性剂离子对应的添加剂反离子是影响其水溶液表面活性的主要因素,因而ＴＡＡＢ对ＳＤＳ表现出明显的效应,对ＤＴＡＢ影响效果则是同浓度的ＮａＢｒ类似,除了对表面活性离子头基电荷的静电屏蔽外,ＴＡＡ＾＋的碳氢基团和ＳＤ＾－碳氢链间还可能发生疏水相互作用,但后者受ＴＡＡ＾＋离子体积制约     

吊片法测试液体表面张力的实验设计

表面张力是液体的重要物性数据,在科学研究、工业生产和日常生活中皆有广泛应用。介绍了采用吊片法测量液体表面张力的实验设计,该实验过程简单,准确度高,实验内容和时间易于调节,对于培养学生认真细致的科研作风有很大帮助。     

Silicon-Modified Carbohydrate Surfactants V: The Wetting Behaviour of Low-Molecular-Weight Siloxane,Carbosilane, Silane and Polysilane Precursors on Low-Energy Surfaces

The surface tensions, wetting tensions, contact angles and solid/liquid interfacial tensions of defined siloxanes as well as those of analogous carbosilanes, polysilanes and neopentyl substituted silanes were determined. The wetting experiments were carried out on a glass plate coated with perfluoroalkyl methacrylate (FC 722^®). The siloxanes possess the lowest surface tensions. Due to the presence of oxygen atoms in the siloxane backbone, a donor–acceptor portion (γ^+/−_lv) of the surface tension of about 1–2 mN/m was determined. The solid/liquid interfacial tension also contains a donor–acceptor portion (γ^+/−_sl). Its value is almost identical to that of γ^+/−_lv. The γ^+/−_sl differences between individual molecules of the same surface tension are responsible for contact angle differences of up to 4°. © 1997 John Wiley & Sons, Ltd.     

Effect of surfactant structure on the adsorption of carboxybetaines at the air–water interface

In order to study the effect of charge on the adsorption of surfactants at the air–water interface, two carboxybetaines have been synthesized with different number of separation methylenes between their charged groups. After purification and structure confirmation, the equilibrium and dynamic surface tensions were measured as a function of surfactant concentration for both the cationic and neutral forms of the surfactant molecules. The effect of ionic strength on the adsorption process was also studied. The equilibrium surface tension values were interpreted according to the Langmuir model and the dynamic surface tension data, converted to surface concentration by the Langmuir parameters, are consistent with the assumption of diffusion control over the range of surfactant concentrations studied. The diffusion coefficients show a progressive decrease in the rate of adsorption when the number of methylene units between the betaine charged groups increase.     

The surface tension of aqueous polyvinylamine and copolymers with <Emphasis Type="Italic">N</Emphasis>-vinylformamide

 The surface tensions of aqueous poly(N-vinylformamide) (PNVF), polyvinylamine (PVAM), and PNVF–PVAM copolymers were measured as functions of pH. The nonionic PNVF gave a pH-independent surface tension of 68 mN/m. The surface tension of PVAM was pH dependent; at pH 10 it was 56 mN/m, whereas it was 71.5 mN/m at pH 3.5. The transition from higher to lower surface tension values occurred most dramatically between pH 8 and 9, reflecting the dissociation behavior of the amine groups. The copolymers showed intermediate behavior. Received: 20 August 2001 Accepted: 26 September 2001     

Interfacial Properties of Aqueous Nonionic Fluorocarbon Surfactant Solutions

The equilibrium, dynamic surface tensions, and surface dilatational elasticity of aqueous solutions of nonionic fluorocarbon surfactant are reported. The critical micellar concentration, CMC (0.023 mM) and equilibrium surface tension (24.6 m N . m^?1) at CMC were measured by Wilhelmy plate method for aqueous solution of C₈F₁₇SO₂N(C₃H₇)(C₂H₄O)_nH (n=20), abbreviated as EF122A. The surface tension decay is slower for C₈F₁₇SO₂N(C₃H₇)(C₂H₄O)_nH (n=10) system, abbreviated as EF122B compared to the EF122A system over short time region, which indicates the slow transport of the surfactant molecules to the surface. The relaxation time for surface tension decay is estimated by fitting a series of exponentials to the dynamic surface tension data and it decreases with temperature for EF122A. Slow exchange of monomers between bulk and interface is reflected in the high elasticity value of the air‐liquid interface for EF122B compared with EF122A within measured frequency window (0.125–1.25 Hz).     

Investigation Static/Dynamic Surface and Interfacial Tension of Some Synthesized Polymeric Surfactants to Enhance the Egyptian Jet Fuel A1 Atomization

In the present work some exthoxylated polyalkylphenol surfactants have different alkyl chains (nonyl and dodecyl) were synthesized. The static surface tension for these surfactants in water and jet fuel A1 was measured and the critical micelle concentration (CMC) for each surfactant was determined. The data show the general trend of decreasing the CMC against the molecular weight of the synthesized polymeric surfactants. The HLB of these surfactants was also calculated. The dynamic surface tension for the synthesized surfactants was measured at CMC. The dynamic interfacial tension for these surfactants with jet fuel A1 at CMC was also measured using the spinning drop technique. The results showed that the effect of the synthesized surfactants on deceasing the time of droplet maturation was significant remarked. The decrease of this time leads to enhance of jet fuel atomization.     

Different Distributions of Counterions in the Surface Layer of Cationic Surfactant Solutions

We have separately determined the surface tension of pure aqueous solutions of cetyltrimethylammonium chloride and cetyltrimethylammonium bromide and their surface potentials by a Kelvin probe system. With the help of Gibbs equation, the surface excess has been determined through approximating the chemical activity of the surfactant by their dilute bulk concentration. In the following, the surface potential—surface excess isotherms were established. Those potential isotherms evidence that cetyltrimethylammonium chloride solution has a higher value compared to that of cetyltrimethylammonium bromide under equal surface excess. This phenomenon is supposed to be owed to the different distributions of chloride and bromide ions within the adsorption layer of the solutions, which can be attributed to the different properties of those two anions.     

Simultaneous study of interfacial tension,surface tension,and viscosity of few surfactant solutions with survismeter

Surfaces and interfaces are receptive valuable significant property of chemical molecules due to their potential to develop several phenomena in a self‐controlled mechanism. Science of surfaces is vast and is being used industrially since time immemorial. Their accurate and simultaneous estimation is necessary; therefore, the survismeter was used for measuring them along with viscosity. Individually tensiometers, X‐ray reflective microscope, and viscometers are used for surface tension, interfacial tension, and viscosity, respectively. These devices are sophisticated, expensive, and individually consume much time and resources with poor reproducibility in measurements. Survismeter is an alternative device for similar measurements together with higher accuracies and reproducibility. It works on a principle of capillary flow and pressure gradient (PG) inside liquid‐holding and air‐filled bulbs. Several liquids have been used for study with ± 0.01 mN/m, ± 0.01 mN/m and ± 1 × 10^?5 N s/m² accuracies in respective data. Copyright © 2008 John Wiley & Sons, Ltd.     

Survismeter 3‐in‐1 for interfacial tension (IFT), surface tension and viscosity measurements simultaneously

Interfacial tension (IFT) (γ_ift, N m^?1) of benzene‐water; and surface tensions (γ, N m^?1) and viscosities (η, N s m^?2) of solvents methanol, ethanol, glycerol, ethyl acetate, n‐hexane, diethyl ether, chloroform, benzene, carbon tetrachloride [CCl₄], formic acid, Acetonitril, and dimethylformamide [DMF] were measured with Survismeter‐IFT. The ± 1.1 × 10^?5 N m^?1, ± 1.3 × 10^?5 N m^?1, and ± 1.1 × 10^?5 N s m^?2 deviations in respective values were noted. It has 10 times better accuracy than those of individual methods. The survismeter is inexpensive minimizing 2/3 each of consumables, human efforts, time, and infrastructure, cutting down 80% of the waste disposed the environment. Copyright © 2008 John Wiley & Sons, Ltd.     

Surface tension of random copolymer melts

A mean-field theory is presented to describe the surface tension and interfacial profile of random A-B multiblock copolymer melts in contact with air or a solid substrate. The copolymer model accounts for variations in average composition and block sequence distribution, and reduces to a model for statistical copolymers as the block size approaches that of a monomer. Ideal copolymers lacking chemical correlations between successive segments are predicted to have a larger surface tension than “blocky” copolymers with a tendency for repeated segments of A or B. © 1992 John Wiley & Sons, Inc.     

Theory of diffusion-controlled adsorption kinetics at the expanding planar surface with a constant area rate

The diffusion equation for the expanding surface was solved and a corresponding general expression of dynamic surface adsorption was derived. For the short-time adsorption, a special factor 1/3, which reflected the effect of the expanding surface on the adsorption, appeared in the equation. In addition, the effects of the surface expansion on subsurface concentration (ϕ(t)), dynamic surface adsorption (Γ(t)), dynamic surface tension (γ(t)) and the adsorption mechanism were discussed. In contrast to the adsorption on a still planar surface, ϕ(t) and Γ(t) are smaller, but γ(t) increased. The adsorption mechanism will be the same as long as the corresponding theories are used.     

1-烷基-3-甲基咪唑系列室温离子液体表面张力的研究

合成了系列1-烷基-3-甲基咪唑四氟硼酸盐([C_2～7mim]BF₄)及六氟磷酸盐([C_4～7mim]PF₆)室温离子液体, 并通过核磁氢谱、红外光谱、质谱等手段对其进行了结构表征; 采用Wilhelmy白金板法, 在293～338 K范围内测定了离子液体的表面张力, 测试结果显示, 同类离子液体表面张力γ随温度的升高而线性下降, 同种离子液体的表面张力呈现出较宽的变化范围, 如293 K下, 表面张力值从[C₂mim]BF₄的50.4 mJ/m²到[C₇mim]BF₄的36.1 mJ/m². 最后对离子液体的表面性能进行了讨论.     

Synthesis of Surfactants from Alkali Lignin for Enhanced Oil Recovery

With the cheap and abundant resource of alkali lignin as feedstock, surfactants for enhanced oil recovery were synthesized by amination and alkylation reaction of lignosulfonate. The effects of amination conditions, including the ratio of raw materials, amination reagent, temperature, and reaction time, on nitrogen contents and surface tension of the surfactants were investigated. The results showed that ethylenediamine was more suitable for amination, and the molar ratio of alkali lignin, ethylenediamine, and formaldehyde was 1:2:1.5 at 80°C for 5 hours. The structure of synthesized products was characterized by Fourier transform infrared spectrometry. The HLB value of synthesized product was 10. The interfacial tension between Daqing crude oil and synthetic water could be decreased to 10^?2 mN/m with synthesized surfactant and NaOH at 45°C. Moreover, the effects of molecular weight of surfactants on interfacial tension were also studied. The synthesized surfactant (M_w > 10,000) showed a better interfacial activity on Daqing crude oil.     

Obtaining surface tension from contact angle data by the individual representation approach

Young equation is the fundamental equation of wetting theory in which the connection among the surface tensions, \(\gamma _{{\varphi \psi }} \) and the contact angle, θ _L, are given. The surface tension of solid surfaces, however, cannot be obtained directly from the Young equation. In this paper, the application of the individual representation theory is demonstrated for the determination of surface tensions of solids (or any phase pair) using experimentally obtained contact angle data. According to this approach, the state of the interfacial layers depends upon, by definition, the properties of the bulk phases in every heterogeneous system, and thus, it complements the traditional capillary theory.