How the Influence of Different Salts on Interfacial Properties of Surfactant–Oil–Water Systems at Optimum Formulation Matches the Hofmeister Series Ranking

In this work, we present the effects of salts on sodium dodecyl benzene sulfonate micellization and on the interfacial performance of a sodium dodecyl benzene sulfonate–heptane–brine system at optimum formulation, i.e., hydrophilic–lipophilic deviation (HLD) = 0. In order to do that, interfacial tension and dilational interfacial rheology properties of surfactant–heptane–water systems at optimum formulation are measured using an interfacial spinning drop tensiometer with an oscillating velocity, which can accurately measure interfacial rheology properties at both low and ultralow interfacial tensions. The brines used contain one of the following salts: MgCl₂, CaCl₂, NaCl, NH₄Cl, NaNO₃, CH₃COONa, or Na₂SO₄. We performed a one-dimensional salinity scan with each of these salts to achieve an optimum formulation. In relation to the Hofmeister series, we found that, at optimum formulation, systems with chaotropic ions (NH₄⁺, NO₃⁻) present interfaces with ultralow interfacial tensions, very low dilational modulus, and a low phase angle, whereas kosmotropic ions (Mg²⁺, Ca²⁺, SO₄⁻²) generate high interfacial tension and high rigidity monolayers. Intermediate ions in the Hofmeister series (Na⁺, CH₃COO⁻, Cl⁻) present interfaces with intermediate properties. Furthermore, according to the Hofmeister series, interfaces can be respectively ordered from higher to lower rigidity for surfactant counterions Mg²⁺ > Ca²⁺ > Na⁺ > NH₄⁺ and coions SO₄²⁻ > CH₃COO^– > Cl⁻ > NO₃⁻, which correspond to a salting-out (highest rigidity) and salting-in (lowest rigidity) effect. We observed that counterions have a more significant effect on surfactant–oil–water system properties than those that act as coions.     

PE/PVC共混物与PE界面黏结性能研究

为改善聚氯乙烯(PVC)和聚乙烯(PE)界面黏结性能,制备了一系列PE/PVC共混物及其与PE的黏结材料,探究了原料比例和成型温度对(PE/PVC)/PE界面黏结性能的影响。结果表明,PE/PVC共混物为不相容体系。共混物中随着PE含量升高,体系拉伸强度增大,断裂伸长率升高。(PE/PVC)/PE材料中,随着PE/PVC共混物中PVC含量升高,PE/PVC与PE的界面黏结强度先升高后降低。成型温度升高,界面黏结性能提高。在PE/PVC比例为60/40、黏结温度为100℃时,PE/PVC共混物与PE的界面黏结强度最大,可与共混物拉伸强度接近。     

Impact of surfactants on the lipase digestibility of gum arabic-stabilized O/W emulsions

The bioavailability of lipids from an emulsion can be controlled and regulated by the property of the stabilizing interfacial layer. Here we evaluate how low-molecular weight surfactants including hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Tween 80 (T80) influence the interfacial behavior of lipase and bile extract on the surface of lipid droplets stabilized with gum arabic (GA). The lipolysis behavior was influenced by surfactant type and concentration. The results showed that anionic SDS could completely displace GA from droplet surface. Cationic CTAB might either adsorb onto existing GA layers or displace GA, whereas non-ionic T80 could co-adsorb with GA on the interface. When the concentration of surfactants was much higher than the critical micelle concentration (CMC), all the surfactants would form a dense adsorption layer on the droplet interface to prevent lipase from the direct contact with lipids. A considerable amount of surfactant in the aqueous phase may also compete with the bile salt and lipase, thus leading to suppressed digestion of lipids. Ionic surfactants would denature the lipase resulting in reduced enzyme activity, and T80 micelles may interact with the lipase, hindering their adsorption onto the droplet interface as well. These results were confirmed both by the digestion model and interfacial techniques. The results provided guidance for the development of emulsion-based delivery systems for functional lipid foods.     

Interfacial and emulsifying behaviour of crayfish protein isolate

The interfacial behaviour of adsorbed protein films constituted with a crayfish protein derivate that is typically produced as by-product from the food industry, has been studied at the air-water and oil-water interfaces. An analysis of the surface pressure under compression-expansion cycles of this protein was carried out as a function of time, concentration and pH (2 and 8). Besides, interfacial tension and adsorption kinetics also were determined as a function of time at different concentrations and pH values. Interfacial rheological properties were studied under dilatational deformations applied to a single droplet, either at the initial step of film formation or once the interfacial tension was at equilibrium and the film was completely formed. The contribution of the interfacial properties to the behaviour of oil-in-water emulsions stabilised with this protein derivative were also analysed. Finally, droplet size distributions obtained for concentrated emulsions stabilised by crayfish protein were analysed and related to the interfacial tension behaviour. We have demonstrated that crayfish proteins at pH 8 show higher solubility, smaller aggregates and better interfacial activity (higher surface pressure and lower interfacial tension) with higher interfacial viscoelasticity, than at pH 2. A two-dimensional model of the results showed that oil-water and air-water interfaces are clearly related to the improved stability of emulsion made with crayfish proteins at pH 8.     

SFG study on potential-dependent structure of water at Pt electrode/electrolyte solution interface

Structure of water at Pt/electrolyte solution interface was investigated by sum frequency generation (SFG) spectroscopy. Two broad peaks were observed in OH stretching region at ca. 3200 cm⁻¹ and ca. 3400 cm⁻¹, which are known to be due to the symmetric OH stretching (υ₁) of tetrahedrally coordinated, i.e., strongly hydrogen bonded “ice-like” water, and the asymmetric OH stretching (υ₃) of water molecules in a more random arrangement, i.e., weakly hydrogen bonded “liquid-like” water, respectively. The SFG intensity strongly depended on electrode potential. Several possibilities are suggested for the potential dependence of the SFG intensity.     

加压湿壁塔内的气液传热传质

本文研究了加压条件下空气水系统在湿壁塔内同向流动时传递行为。分析中考虑了界面处气相混和物非理想行为及剪切应力的影响,忽略传质对气体运动影响。提出了计算加压条件下气侧局部传热传质系数关系式,并对两相加压下传递行为进行系统地分析。分析结果表明,采用常压计算方法进行加压传热传质计算,将产生较大的偏差。     

端面粘贴包覆火药界面粘结强度研究

包覆火药装药控制燃气生成速率，降低弹性温度系数，提高弹丸初速的效果部分来自于包覆层的作用，对预制包覆层端粘包覆火药，其包覆层的厚度，密度，强度等性能已根据弹道和装药表确控制，包覆层与基药的界面粘结度就决定了包覆层控制燃气生成速率的有效性和可靠性，它是检验端面粘贴包覆火药工艺质量的关键指标，本文采用落锤实实验检包覆火药的界面结强度，研究了粘结工艺条件对端面粘贴包覆火药界面粘结强度的影响，通过实验选择出了合适的粘结剂及粘结工艺条件，制备了界面粘结强度良好的端面粘贴包覆火药。     

Formation and Phase Behavior of Winsor Type III <Emphasis Type="Italic">Jatropha curcas</Emphasis>-Based Microemulsion Systems

The formation and phase behavior of Jatropha curcas-based microemulsion systems, which could potentially be used in enhanced oil recovery applications, has been investigated. Winsor type III microemulsions were obtained by adding n-octane to Winsor type I microemulsion systems prepared using various concentrations of alkyl polyglucoside (APG). To optimize the formulation of type III microemulsion systems, five different types of co-surfactants, i.e. normal butyl alcohol (NBA), isobutyl alcohol, isopropyl alcohol, fatty acid alcohol C8 (FAC8) and fatty acid alcohol C8/C10 (FAC8/C10) were used. The microemulsion phase behavior was determined along with particle size distributions by dynamic light scattering measurements. Results show that the optimum Winston type III system can be achieved by mixing 3 wt% of NBA, 1 wt% APG and 3 wt% NaCl. At the optimum formulation, the IFT reached a minimum value (0.016 mN/m) and formed very small emulsion droplets with a narrow particle size distribution.     

Influence of coalescence and interfacial tension on the morphology of PP/HDPE compatibilized blends

In this paper, the compatibilization of polypropylene (PP)/high-density polyethylene (HDPE) blend was studied through morphological and interfacial tension analysis. Three types of compatibilizers were tested: ethylene-propylene-diene copolymer (EPDM), ethylene-vinylacetate copolymer (EVA) and styrene-ethylene/butylene-styrene triblock copolymer (SEBS). The morphology of the blends was studied by scanning electron microscopy. The interfacial tension between the components of the blends was evaluated using small amplitude oscillatory shear analysis. Emulsion curves relating the average radius of the dispersed phase and the interfacial tension to the compatibilizer concentration added to the blend were obtained. It was shown that EPDM was more efficient as an emulsifier for PP/HDPE blend than EVA or SEBS. The relative role of interfacial tension reduction and coalescence reduction to particle size reduction was also addressed. It was observed that the role of coalescence reduction is small, mainly for PP/HDPE (90/10) blends compatibilized by EPDM, EVA or SEBS. The results indicated that the role of coalescence reduction to particle size reduction is lower for blends for which interfacial tension between its components is low at compatibilizer saturation.