STABILITY OF THE LENSLIKE LIQUID THICKENING (THE DROP) ON A SOLID SUBSTRATE

The quasi equilibrium of a liquid lens or a liquid drop on a solid substrate is considered on the basis of the thermodynamics of microscopic thin liquid films. Both contact angles, corresponding to the membrane model and to the finite thickness layer convention of the film, have been derived as a function of the disjoining pressure isotherm. The analytical expressions for the line tension terms have been obtained, and the criterion for the stability of a liquid drop on a solid substrate has been proposed.     

Molecular weight distribution in living polymerization

An easily obtained parameter for characterizing polymers is the molecular weight distribution (MWD). Polymers with different MWD have different properties. The MWD can be easily influenced with controlled polymerization technologies. Examples of how these methods influence the properties of block and gradient copolymers in wetting and dispersing additives are discussed. These wetting and dispersing additives are used to make solvent-borne paints and aqueous pigment concentrates. An advantage of modulation of the MWD is the ability to fine tune-specific properties, such as the compatibility or the wetting activity of the polymer.     

Agglomeration in suspension of salicylic acid fine particles: Analysis of the wetting period and effect of the binder injection mode on the final agglomerate size

Agglomeration in suspension is a size enlargement method which facilitates the operations of solid processing such as filtration, transport and galenic while preserving the solubilisation properties of fine particles. A small quantity of binding liquid is added into a suspension of microparticles, directly in the stirred vessel where the precipitation or crystallisation took place. With optimised quantity of binder injected and optimised injection mode, spherical and dense agglomerates can be obtained. This paper analyses the first step of the agglomeration process, i.e. the wetting period, which corresponds to the injection of the binder liquid and its dispersion within the particle suspension. The system studied is the agglomeration of salicylic acid microparticles using chloroform as binder. A visualisation cell was developed in order to observe under optical microscope the interactions between a liquid binder droplet and the particles to be agglomerated. Clearly, an immersion mechanism was observed. Experiments were also carried out in a stirred vessel to visualise the wetting phase within the reactor using an image acquisition probe. The effect of the injection mode and quantity of binder on the agglomerate size was analysed. A fast binder injection under high stirring and an optimum quantity of binder favour the formation of small agglomerates.     

纳米碳酸钙表面改性的初步研究

应用几种脂肪酸对纳米碳酸钙进行表面处理，对它们的改性效果进行了比较，透视电镜（TEM）分析结果表明：改性纳米碳酸钙粒子在乙醇中的分散性得到了提高；图像分析显示；改性碳酸钙颗粒的粒径分布有所改善；润湿性测定结果预示：改性粒子与聚合物将具有较好的相容性和亲和性。     

An efficient dynamic uniform Cartesian grid system for inundation modeling

A dynamic uniform Cartesian grid system was developed in order to reduce the computational time in inundation simulation using a Godunov-type finite volume scheme. The reduction is achieved by excluding redundant dry cells, which cannot be effectively avoided with a conventional Cartesian uniform grid system, as the wet area is unknown before computation. The new grid system expands dynamically with wetting, through addition of new cells according to moving wet-dry fronts. The new grid system is straightforward in implementation. Its application in a field-scale flood simulation shows that the new grid system is able to produce the same results as the conventional grid, but the computational efficiency is fairly improved.     

Enhanced wetting properties of silicon mesh microchannels coated with SiO2/SnO2 nanoparticles through layer-by-layer self assembly

The enhanced wetting property of silicon mesh microchannels coated with SiO₂/SnO₂ nanoparticles is presented in this paper. The SiO₂/SnO₂ bi-layers are prepared using layer-by-layer nano self assembly. It is found that the silicon mesh microchannels are super hydrophilic and demonstrated powerful capillary. The capillary rise rate is characterized by measuring the front location of liquid on the silicon mesh surface, laid on a 45° inclined platform. For a silicon mesh sample with an overall dimension of 25 mm × 25 mm, when the microchannel width is 0.5 mm, the liquid front can reach the top edge of the sample in approximately 30 s. The mesh silicon surface with a SiO₂/SnO₂ multilayer film presented in this paper has better wettability and higher capillary pressure than other hydrophilic surfaces reported. The results provide a new way to improve the capillary in microchannels with enhanced super hydrophilic surfaces in microchannels for variety of micro/nanofluidic applications.     

Adhesive Contact of a Membrane with a Hemispherical Indenter: Theoretical Analysis and Model Liquid System

The axisymmetric Laplace equation is solved numerically to extract contact-angle data for a flat liquid/vapor interface contacting a submerged hemispherical solid. The liquid/vapor interface is treated as a membrane, with a membrane tension equal to the surface energy of the liquid. By measuring the vertical displacement of the membrane and the projected contact area the membrane makes with the hemisphere, the contact angle and correspondingly the driving force for motion of the contact line can be measured. We show that characteristic receding and advancing contact angles can be obtained by measuring the contact radii formed upon initial contact between the interface and hemisphere and final contact just prior to detachment of the interface, respectively. Use of the technique is illustrated with a model experiment involving the contact of an air/water interface with a poly(methyl methacrylate) surface.     

Reversible and Irreversible Adhesion of Polymers: Possibilities for Measurement and Calculation

Comparative analysis of existing direct and indirect techniques for estimation of the work of adhesion (W_A) between a polymer and a solid surface - inverse gas chromatography (IGC), wetting, direct adhesion forces measurement - has been carried out. The work of adhesion was calculated from experimental data obtained using different techniques for identical polymer/solid systems. The relationship between the work of adhesion and the bond strength was analyzed, including possible W_A estimations from destructive micromechanical tests. For non-polar polymers, whose adhesion is due to dispersion interaction only, all techniques are in good agreement with each other. However, the estimates of work of adhesion obtained by different techniques considerably differ for polar polymers. The reason for this obviously consists in deficiency of theoretical knowledge about non-dispersion interactions at interfaces. Each of the considered approaches has its own advantages and shortcomings. The problems concerning the estimation of non-dispersion component of the work of adhesion can be solved only by comprehensive use of several different techniques.     

压敏湿法转移技术

介绍了一种新的压敏胶转移方法－－湿法转移技术。研究了橡胶溶剂和丙烯酸酯乳液型压敏胶对橡胶泡沫切片的湿法转移施胶工艺；对转移后胶层与基材的附着力进行了试验。研究表明，湿法转移技术可以较好地解决压敏胶干式转移中存在的附着力、转移困难及起泡等问题。