纤维临界表面张力测定技术

用ＷＤＳ－Ｉ型接触角测定仪可测定纤维材料的临界表面张力，用硅烷偶联剂处理玻璃纤维，测定偶联剂处理前后玻璃纤维临界表面张力的变化，可了解偶联剂对玻璃纤维表面浸润性能的影响。因此临界表面张力测定技术是复合材料界面研究的一种重要方法。     

Asymmetric Three-Phase Surface Tension Forces in Agglomerating Particulate Systems

In accurate simulation of surface tension dominating systems, such as particulate systems in the nano- and mesoscale, the computation of interface curvature is essential. In a previous work a formulation using discrete differential geometry was demonstrated that could be used to find exact equilibrium solutions of surfaces. However, it was also shown that this formulation, as well all other tested formulations from those found in literature, fail to find accurate point-wise estimates for curvatures for particle-particle capillary liquid bridges. In this communication we elaborate on how total curvatures can be used for computing forces of parameterized models as well as in direct numerical simulations and demonstrate the infeasibility of using point-wise estimates on any asymmetric discretization. Near-exact numerical solutions are demonstrated for asymmetrically triangulated Catenoids and a minimal surface suitable for modeling liquid bridges between particles of different diameters.     

Critical Surface Tension of Wetting and Flotation Separation of Hydrophobic Solids

Abstract

Wetting characteristics of a number of minerals including layer-type hydrophobic minerals as well as common sulfides were investigated. For the majority of the minerals, the critical surface tension of wetting, γ_c determined using Zisman's technique was in the range of 40 to 45 mN/m. Surface pressures of water, II_e, on molybdenite and coal samples were determined from adsorption isotherms. The dispersion component of the surface-free energy, γ_s ^d, for molybdenite was estimated to be 113 ± 3 mJ/m² as compared to the γ_s ^d value for graphite, 109 mJ/m². The wettability data of aqueous methanol solutions, presented in the form of adhesion tension diagrams, yielded significantly lower γ_c values. Flotation behavior of common sulfides, which was similar to that of inherently hydrophobic polymers and minerals, was attributed to elemental sulfur formation. The relevance of critical surface tension of wetting to selective flotation and separation of hydrophobic solids is discussed.     

Application of the Critical Surface Tension Concept to Items in Our Everyday Life

One form of tribute to a scientist is the utilization of his work to advance technology. This review is to cite the application of Zisman's work to what are perhaps some unusual, or at least unfamiliar, technologies-dental restoratives, hair treatment, shaving and the processing of wastes. I have singled out these few because of personal involvement and recognition of the large contribution of Zisman and co-workers in their advancement and understanding. This, then, is a narrow and personal review of the scientific contributions of William A. Zisman.     

Critical Surface Tension of Acrylamide-Grafted Polypropylene Copolymer by the Contact Angle Method

The contact angles θ of polar liquids on PP-g-AM copolymer (AM content 0.19, 0.26, and 0.37 wt%) were measured. The critical surface tension γ_C of PP-g-AM films were evaluated by the Zisman plot (cos θ versus-γl), the Young-Dupre-Good-Girifalco plot (1 + cos θ) versus 1/γ^0.5 l, and the log(1 + cos θ) versus log-γl plot. The-γl values estimated by the plot log(1 + cos θ) versus log-γl were smaller than those obtained by the other plots.     

几种植物临界表面张力值的估测

通过测定水稻、小麦、包菜、棉花等植物临界表面张力值的实例,阐述了测定植物临界表面张力值的方法与过程。测定结果表明,水稻、包菜与棉花的临界表面张力值相差近一半,说明不同植物的临界表面张力值有很大的差异。     

Molar Volume and Surface Tension of Fused Metaphosphate—Sulfate Systems

Molten oxides have been of potential interest as fuels for nuclear reactors. To obtain additional information about the constitution of these systems, the molar volume and surface tension of the NaPO₄–Li₂SO₄, NaPO₄–Na₂SO₄, NaPO₄–Rb₂SO₄, and NaPO₃–UO₂SO₄ solutions were determined for the NaPO₂–rich region. The observed properties were found to vary linearly with temperature in all cases. Although the results of other types of investigations were found to be nonideal, the volume behavior of all the mixtures was additive.     

Synergistic Effect of Mixed Surfactant Systems on Foam Behavior and Surface Tension

Foam and surface tension behaviors of different ionic/nonionic surfactant solutions along with their different combinations have been investigated. Among different surfactants, sodium dodecyl sulfate showed the highest foamability over other surfactants. Mixed surfactant systems were always found to have higher foamability than the individual surfactant. It was also noticeable that nonionic surfactants show good foamability when they combine with anionic and cationic surfactants. In the case of mixed surfactant systems, nonionic/cationic surfactant mixtures showed lower surface tension than nonionic/anionic surfactant mixture due to a synergistic effect.     

Metal-Ceramic Interactions: III, Surface Tension and Wettability of Metal-Ceramic Systems

The wettability and adherence of metal–ceramic systems were investigated, using a precise sessile–drop method. The surface tension and wettability of silicon, iron, and nickel in contact with various refractory materials were evaluated at elevated temperatures. Measurements were carried out in vacuo , in hydrogen, and in helium. Generally, nonwetting contact angles were observed for iron and nickel with oxides, whereas silicon was found to wet the oxides partially. In all cases the wettability was greater for the metal-graphite and beryllium carbide systems than for the metal-oxide systems. The nature of the atmosphere was found to have a significant effect on the wettability and surface tension of the metal. Wettability results are interpreted on the basis of surface tension and by the consideration of free-energy changes.     

Surface Tension and the Gibbs Approach

In the Gibbs capillarity equation, it is necessary to use the excess surface tension whose value is a function of the position of the dividing surface. The thermodynamic properties of disperse systems can be determined with the Guggenheim approach, since there are reliable experimental methods of determining the thickness of the interface layer for polymer dispersions. __________ Translated from Khimicheskie Volokna, No. 3, pp. 60–61, May–June, 2005.     

Segregation of Mg to the (0001) Surface of Doped Sapphire

Auger electron spectroscopy (AES) and low-energy electron diffraction (LEED) were used to study the segregation of Mg to the surface of a sapphire crystal doped with 40 ppm of Mg. In situ vacuum annealing and AES measurements at 900° to =1800°C failed to reveal Mg segregation on the (0001) plane above the detectability limit of the cylindrical mirror analyzer. However, when identical crystals were placed together to simulate a "closed system" and annealed in air, surface segregation of Me was detected above 1200°C. The variation of the equilibrium surface concentration of Mg with temperature in the range 1300° to =1500°C, gave an effective Langmuir heat Of segregation of Mg of =–146 kJ/mol. Evidence for the formation of a two-dimensional ordered structure on the sapphire surface was also obtained through LEED studies. The implications of these segregation results for our understanding of the sintering behavior of magnesia-doped alumina are discussed.     

Critical Surface Tension of Non-crosslinking Linear Low Density Polyethylene-graft-acrylic Acid by the Contact Angle Method

Abstract

The contact angles θ of polar liquid on surface of non-crosslinking linear low density polyethylene-graft-acrylic acid (LLDPE-g-AA) were measured. The critical surface tension (γ_c) of LLDPE-g-AA films were evaluated by three different plots, the Zisman plot, the Young-Dupre-Good-Girifalco plot, and the log(1 + cos θ) versus log θ _L , plot. The θ _c of LLDPE-g-AA obtained by the 1 + cosθ versus θ _L ^?1/2 plot were higher than those obtained by other plots.     

镁合金表面处理工艺及有机防护涂层耐腐蚀性能

为提高镁合金的耐腐蚀性能,研究了镁合金的化学转化膜技术原理、有机防腐涂装层次结构及其涂膜防腐性能。结果表明该化学转化膜可以提高镁合金与有机涂层的结合力,同时配套复合有机涂层体系对镁合金有较好防护及耐腐蚀性能。     

确定固体聚合物表面张力方法的研究

应用熔体悬滴测量装置,以聚乙烯,聚乙二醇和聚乙二醇醋酸酯为体系,系统地测量了不同温度下聚合物熔体的表面张力以及不同相对分子质量同系液体聚合物的表面张力,并比较了向低温和高相对分子质量的两种外推法间接测量固态高聚物表面张力的方法。     

磺化聚醚醚酮／氧化石墨复合膜的制备与表征

采用液相氧化法制备了氧化石墨（GO）,以浓硫酸为磺化剂与聚醚醚酮反应制备了磺化聚醚醚酮（SPEEK）。采用溶液共混法制备了不同组成的SPEEK／GO复合膜,并运用FTIR、XRD、DSC、TG对复合膜进行了表征。研究表明,当氧化石墨和磺化聚醚醚酮复合后,氧化石墨的层间距由0．8nm增大至1．1nm,这说明磺化聚醚醚酮极性基团或者高分子链段已经插入到氧化石墨片层之间。DSC结果显示,氧化石墨的加入,在一定程度上降低了SPEEK的结晶性能。TG分析表明,在温度低于300℃,复合膜的热稳定性比磺化聚醚醚酮的略有降低,但当温度高于450℃后,复合膜的热稳定性反而得到提高。     

Thermally Conductive General-Purpose Polystyrene (GPPS)/Graphite Composite with a Segregated Structure: Effect of Size of Resin and Graphite Flakes

General-purpose polystyrene (GPPS)/graphite flake composites with a segregated structure were fabricated by newly developed binder mixing method, aiming at highly thermally conductive polymer composites. The coefficient of thermal conductivity of the GPPS/graphite composites can be easily improved to be 3.5?W?m^?1?k^?1 at a graphite flakes loading of 24.7?vol%, showing an improvement of more than 2,000% compared with pure GPPS. The thermal conductivity of the composites increased with the increasing particle size of graphite flakes, while the mechanical properties of composites are decreased with the increasing particle size of GPPS resin particles.     

借助变阱宽方阱链流体状态方程模拟非电解质体系表面张力和粘度(英文)

The equation of state(EOS)for square-well chain fluid with variable range(SWCF-VR) developed in our previous work based on statistical mechanical theory for chemical association is employed for the correlations of surface tension and viscosity of common fluids and ionic liquids(ILs).A model of surface tension for multi-component mixtures is presented by combining the SWCF-VR EOS and the scaled particle theory and used to produce the surface tension of binary and ternary mixtures.The predicted surface tensions are in excellent agreement with the experimental data with an overall average absolute relative deviation(AAD)of 0.36%.A method for the calculation of dynamic viscosity of common fluids and ILs at high pressure is presented by combining Eyring’s rate theory of viscosity and the SWCF-VR EOS.The calculated viscosities are in good agreement with the experimental data with the overall AAD of 1.44% for 14 fluids in 84 cases.The salient feature is that the molecular parameters used in these models are self-consistent and can be applied to calculate different thermodynamic properties such as pVT,vapor-liquid equilibrium,caloric properties,surface tension,and viscosity.     

梯度理论用于烃类表面张力计算

应用梯度理论和状态方程（Ｐｅｎｇ－Ｒｏｂｉｎｓｏｎ方程与Ｐａｔｅｌ－Ｔｅｊａ方程）相结合的半理论方法,计算了正构烷烃的表面张力,提出了关联作用参数Ｃ的新方程。结果表明：采用新的作用参数方程式计算的表面张力值与文献中的实验值相当吻合。     

Critical Surface Energies of Al2O3 and Graphite

Based on the wetting properties of a -Al₂O₃, and pyrolytic graphite by liquid metals, the critical surface energy for spreading was determined and compared with the surface energy of the ceramics. The surface energy γ-₈ (ergs/cm²) of the (0001) surface of a -Al₂O₃ is estimated to be 892–0.12 T (°C), that of the c plane of pyrolytic graphite 1139–0.13 T (°C), and that of the a plane of pyrolytic graphite 1300–0.17 T (°C). Also, the liquid-solid interfacial energies were calculated and found compatible with the values reported in the literature. The surface energy of liquid Ag or liquid Cu is not significantly affected by carbon.