An Examination of Surface Tension of Binary Lithium Borate Melts as a Function of Composition and Temperature

Surface tensions of x Li₂O–(1− x )B₂O₃ melts, where 0≤ x ≤0.68, have been measured systematically with a ring method from respective liquidus temperatures up to about 1450 K. For all of the investigated melts, the relationship between surface tension and temperature can be well described by quadratic polynomial functions. With increasing Li₂O content, surface tension monotonously increased, whereas the temperature coefficient of surface tension increased slowly up to about x =0.1, changed sign from positive to negative at about x =0.2, and then remained negative with further increasing Li₂O content. Together with the physical properties reported in our previous work, such as density, temperature coefficient of density, and volume expansion coefficient, etc., both surface tension and temperature coefficient of surface tension have been comparatively plotted as a function of Li/B molar ratio. Differentiated from the inflections of slope in the plots of physical properties vs. Li/B molar ratio, three characteristic regions have been found in the melts of this system. Within different regions, different effects of temperature and concentration on the physical properties of melts have been observed.     

Laser-Sintered Bismuth Germanate Ceramics as Scintillator Devices

We have investigated the potential use of Bi₄Ge₃O₁₂ (BGO) laser-sintered ceramics in scintillator devices for radiation detection. Relevant results from the characterization made during the ceramic processing are presented, such as particle size analysis, X-ray diffraction studies, and thermal analysis. Furthermore, we have compared the microstructure, relative density, thermoluminescent (TL) emission, and transparency degree of ceramic bodies sintered by CO₂ laser heating with a reference set of ceramics sintered in an electrical furnace, and also with single crystals grown by the Czochralski technique. It was observed that the laser-sintered BGO presented a relative density of 98% (±2%), better pore shrinkage, larger grains, and light transmission intensity 1.5 times higher than the BGO ceramics sintered in a furnace. The TL curves of all samples irradiated with UV and β−rays presented peaks at 75°, 102°, and 143°C, and provided strong indication that the intergrain defects have the same nature of the bulk defects and do not contribute with new traps in the temperature range studied. The relative areas of the total TL emission after β irradiation were 6,0:4,4:1 for the reference ceramic, laser sintered ceramic, and single crystal, respectively. For UV irradiated samples, this relation was 7,1:4,7:1. From these results, we have concluded that laser-sintered ceramics have an amount of charge traps lower than the conventionally sintered BGO samples, thus having a higher radioluminescence yield.     

Viscosity and Surface Tension of Oxynitride Glass Melts

The viscosities and surface tensions of three MgO-Al₂O₃-Y₂O₃-SiO₂-based oxynitride glass melts were measured. Glass transition temperature, Littleton temperature, and sink-in temperature were obtained, and by using the Vogel-Fulcher-Tammann equation the viscosities were calculated from T _g (820° to 940°C) to 1600°C. The surface tensions were measured by the drop weight and the drop geometry methods and displayed values between about 500 and 600 N.mm⁻¹. These values are about a factor of two higher than the surface tensions of oxide glass melts.     

Temperature Dependence of Interfacial Tension of Polymer Melts

A unique behavior of interfacial tension of polymer melts is that, in an ordinary temperature region of strong segregation, the entropy effect of chain molecules on the composition-gradient term in the free energy at the interface can make the interfacial tension increase with increasing temperature. To confirm this role of the entropy, interfacial tension of polystyrene/poly(dimethylsloxane) was measured as a function of temperature, and was found to increase with increasing temperature. Using temperature dependence of the segment-segment interaction parameter, which was evaluated from experimental coexistence curves, it was shown that the entropy effect was responsible for this positive temperature dependence of the interfacial tension. The experimental result was also discussed on the basis of scaled expressions of interfacial tension as a function of segregation strength covering weak, strong, and very strong segregation regimes.     

Surface Tension of Some Liquid Oxides and Their Temperature Coefficients

Surface-tension data are reported for liquid Al₂ O₃, B₂ O₃, GeO₂, P₂ O₅, and SiO₂. Abnormal positive temperature coefficients for B₂ O₃, GeO₂, and SiO₂ are shown to be due mainly to changes in the liquid structure (dissociation) with temperature.     

高密度聚乙烯／木粉复合材料熔融性能及表面张力的研究

探讨了木粉及马来酸酐接枝聚乙烯(MAPE)对高密度聚乙烯(HDPE)/木粉复合材料熔融性能及表面张力的影响。结果表明:复合材料的起始熔融温度均略高于纯HDPE的,熔融峰的面积及形状介于纯木粉与纯HDPE之间,复合材料的表面张力及其极性组分均随木粉的质量分数逐渐增加。使用MAPE将提高复合材料熔融峰的面积,复合材料更难被熔化。质量分数为5%、10%的MAPE的复合材料的表面张力较低;而质量分数为15%及20%的MAPE的复合材料的表面张力与无MAPE的复合材料的基本相等。     

On the Surface Tension and its Temperature Variation in Film-Forming Polymers

A thermal gradient bar has been used for convenient measurements of γ_c and dγ_c/dT in complex polymers used as film-formers. The technique yields both γ_c and its temperature variation in one experimental sequence well suited for rapid, routine applications. Surface tension data have been obtained for a styrene-acrylic terpolymer, and these have also been used to characterize the compatibility of external plasticizers for the polymer. The surface tension approach has shown that glyceryl dibenzoate, though compatible with the polymer at temperatures above ∼70°C becomes incompatible at use temperatures, and exudes to the polymer film surface. Measurements of moisture sensitivity in plasticized polymer samples have confirmed the incompatibility and illustrated one of the applications to which the gradient bar and its data generation potential may be put.     

Influence of Liquid Density and Surface Tension on the Pinning of Sliding Droplets on a Triangular Microstructure

Sliding droplets are crucial in many industrial applications. Examples are coating and separation processes involving multiple phases and liquid films. Often one can observe how a sliding droplet halts midstream on a solid surface. Wetting defects such as topographic structures can lead to a pinning of sliding droplets. In order to assess the influence of liquid density and surface tension on the pinning, direct numerical simulations are performed. After the model and its discretization are introduced, the solution is validated. Simulation results of gravity‐driven droplets on inclined surfaces with structures in the size of the droplets are presented and the observed requirements for pinning a sliding droplet to a surface are discussed.     

Influence of Temperature on the Surface Tension of Triton Surfactant Solutions

The surface tension of different Triton surfactants (X-100, X-405, and X-705) with or without adding sodium chloride was measured in the temperature range between 20 and 40°C using the maximum bubble pressure method. Rising temperature reduced the surface tension of Triton surfactants via disrupting the H-bonds between the ethylene oxide (EO) group and water. Increasing the number of the EO groups created the steeper thermal gradient of the surface tension. The data indicated that EO-water bonds are easier to be broken by rising temperature than the water–water H-bonds, with an entropy change of −0.535 J deg⁻¹ per mole of EO. The presence of NaCl decreased the surface tension for all systems. However, NaCl produced a synergistic effect with surfactants on the surface tension.     

Density, Surface Tension, and Viscosity of PbO-B2O3-SiO2 Glass Melts

The density, surface tension, and viscosity of the melts from the PbO-B₂O₃-SiO₂ system have been measured at temperatures in the range 1073–1473 K. The effect of composition on these properties was also investigated. The density of the melt was found to increase linearly with increasing PbO content. Molar volume was derived from the density data, and its deviation from the additivity of partial molar volumes was calculated. These deviations in molar volume from those obtained from additivity rules have been used along with the ratio of various coordination numbers of boron (as reported by Bray) to discuss the structure of the melts. The surface tension was found to decrease with decreasing SiO₂/B₂O₃ ratio, and to increase in the range of the PbO content between 30 and 60 mol%, showing a maximum at ∼60 mol% PbO, and then decreased with further additions. This result suggested that the surface tension would be affected primarily by the B₂O₃ content in the range of the PbO content between 30–60 mol%, and mainly by the PbO content in the range of the PbO content >60 mol%, respectively. The viscosity of the melt was found to decrease linearly with increasing PbO content. The results obtained indicate that the increase in viscosity with B₂O₃ was half that of SiO₂ (on a molar basis), and an empirical equation has been proposed for the viscosity as a function of mole fraction.     

Vapor Pressure of Hypostoichiometric Urania as a Function of Composition

The vapor pressure of hypostoichiometric urania was measured as a function of temperature for a series of compositions. The data were obtained by an entrainment technique in which weight loss of a specimen vaporizing at high temperatures in a stream of carrier gas is followed continuously with a recording thermobalance. Use of suitable atmospheres produced constant vaporizing compositions which vaporized pseudocongruently. Equations obtained for the vapor pressure are:
     

化学组成对OLED基板玻璃熔体表面张力的影响

以 OLED基板玻璃为研究对象,基于座滴法进行玻璃熔体表面张力实验,研究化学组成对无碱铝硼硅玻璃表面张力的影响.研究结果表明:Al2 O3/SiO2 和 MgO/RO (RO 为碱土金属氧化物总和)的增加会导致玻璃熔体表面张力增大,增加 ZnO/(ZnO+SrO)有降低玻璃熔体表面张力的作用;增加 RO/(Al2 O3+B2 O3 ),玻璃表面张力会呈现先增大后减小的趋势,且在RO/(Al2 O3+B2 O3 )=1 处出现极大值.     

Composition, Structure, and Properties of Oxide-Salt Melts

The structure and properties of high-basicity aluminoferrosilicate melts in the presence of individual and complex additives are investigated. The obtained regularities of modification of viscosity, surface tension, and structure of clinker liquid depending on the type and concentration of modifiers can be used to predict kinetics of liquid-phase sintering in different silicate systems.     

Surface Tension, Density, Viscosity, and Electrical Resistivity of Molten Binary Alkaline-Earth Borates

Results of an investigation of some properties of the systems CaO-B₂O₃, SrO-B₂O₃, and BaO-B₂O₃ are reported. The formation of two liquids at low RO concentrations limited the range of compositions which could be measured. The values of surface tension and temperature coefficient of surface tension obtained for compositions where two immiscible liquids exist corresponded closely to those for pure B₂O₃. At RO concentrations above the two–liquid regions the surface tension rose sharply with increasing RO content. The densities in the liquid range as well as at room temperature were in the order Ba > Sr > Ca. The introduction of RO into B₂0₃ caused contractions in the glass network; the order of the contracting effect was Ca > Sr > Ba. Neither the method of Huggins or of Stevels was satisfactory for representing the density behavior of these glasses. The viscosity isotherms of barium borate liquids in the temperature range 850° to 950°C. showed maxima at about 22 to 23 mole yo BaO; the other two systems were too fluid for the counterbalanced sphere apparatus used in this work. The equivalent conductance increased with RO concentration; the order for both specific and equivalent conductance at corresponding concentrations was Ba > Sr > Ca.     

Calculation of Temperature Dependences of the Viscosity and Volume Relaxation Time for Oxide Glass-Forming Melts from Chemical Composition and Dilatometric Glass Transition Temperature

The relaxation parameter K _sthat is equal to the ratio of the viscosity to the Kohlrausch volume relaxation time _s is analyzed. It is shown that this parameter can be evaluated from the temperature T ₁₃(corresponding to a viscosity of 10¹³P) and the glass transition temperature T ₈ ⁺determined from the dilatometric heating curve. The maximum error of the estimate with due regard for experimental errors is equal to ±(0.4–0.5)logK _sfor strong glasses and ±(0.6–0.8)logK _sfor fragile glasses, which, in both cases, corresponds to a change in the relaxation times with a change in the temperature by ±(8–10) K. It is revealed that the viscosity, the Kohlrausch volume relaxation time _s , and the shear modulus Gof glass-forming materials in silicate, borate, and germanate systems satisfy the relationship log( _s G/) 1. The procedure for calculating the temperature dependences of the viscosity and the relaxation times in the glass transition range from the chemical composition and the T ₈ ⁺temperature for glass-forming melts in the above systems is proposed. The root-mean-square deviations between the calculated and experimental temperatures T ₁₁and T ₁₃are equal to ±(6–8) K for all the studied (silicate, borate, germanate, and mixed) oxide glass-forming systems. The proposed relationships can be useful for evaluating the boundaries of the annealing range and changes in the properties and their temperature coefficients upon cooling of glass-forming melts.     

Investigation of Relationship between Surface Tension of Feed Solution Containing Various Proteins and Surface Composition and Morphology of Powder Particles

The surface tension of freshly created food protein powder isolates was measured in aqueous solutions as a function of concentration, hydrolysis, and temperature. The surface tension of the solutions was measured immediately to best predict their surface-active behavior in a spray-drying scenario, where instantaneous values are more relevant than equilibrium surface tension measurements. Whole whey protein, hydrolyzed whey proteins (degrees of hydrolysis of 4, 9.5, 12, 17, and 20.2%), soy protein, pea protein isolates, and gelatin powders were diluted in a range of concentrations (0.04–2 g/L) and their surface tension values were reported at 23 ± 1°C. It was found that at higher concentrations hydrolyzed whey proteins at degrees of hydrolysis of 9.5 and 12%, and soy protein isolates in particular, showed excellent surface activity (shown through a decrease in surface tension) compared to nonhydrolyzed whey protein and gelatin. When comparing the influence of the degree of hydrolysis of whey proteins, the reverse was observed at lower concentrations (0.04–0.1 g/L), with the nonhydrolyzed whey protein reducing surface tension values more effectively than their hydrolyzed counterparts.

Additionally, the protein solutions (2 g/L) were maintained at higher temperatures of 40, 50, and 60°C and the surface tension values were measured. There was a general improvement of surface activity of proteins indicated by the reduced surface tension of solutions at these temperatures compared with the pure water values. The protein solutions were also spray dried with maltodextrin (MD30) and the powder particle surface composition and structures were analyzed via X-ray photoelectron spectroscopy and scanning electron micrography. There was a trend of correlation between the surface activities of protein in solution with that of the surface composition of protein found on the powder particles. However, there were morphological indicators that corresponded well to the amount of protein present on the surface.     

The Shock Initiation Threshold of HNS as a Function of its Density

The shock initiation threshold of hexanitrostilbene (HNS) pellets with different densities has been investigated by performing small‐scale gap tests. As the sensitivity of HNS strongly depends on the density of the pellet, the density was varied in a range that the pellet material can be expected to be insensitive by means of no initiation at pressure loads of 2.6 GPa. In the case of HNS we observed that the material became insensitive at densities larger than 1.65 g cm⁻³. Further, we found that the pressure loads can be increased from 2.6 GPa to 3.29 GPa for densities increasing from ϱ=1.65 g cm⁻³ to ϱ=1.70 g cm⁻³ (98% TMD) without detonation of the HNS pellet.     

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.     

Elastic Constants of Polycrystalline BeO as a Function of Pressure and Temperature

The sound velocities of polycrystalline BeO and their pressure and temperature derivatives were determined by a pulse superposition method. The derivatives found from the measurements at pressures up to 2 kbars and near 25° are: (∂ _ul/∂P)_T = 6.48×10⁻³ km/s kbars, ∂ _S/∂P)_T = 0.33×10⁻³ km/s kbars, ∂ _L/∂T)_P =−2.8×10⁻⁴ km/s deg, and ∂ _S/∂P)_T =−2.0×10⁻⁴ km/s deg. The very low value of ∂ _S/∂P)_T is anomalous for crystalline solids but may be expected from the crystal structure in view of similar anomalous behavior found in other solids with the wurtzite structure. The Grüneisen parameter calculated from the pressure derivatives of sound velocities was small compared with the Grüneisen parameter obtained from thermal properties. This result seems to indicate that the thermal expansivity of BeO does not change with temperature in proportion to the specific heat at low temperatures.