Temperature Dependence Of Interfacial Tension Research Articles

Synchronization of Marangoni waves by temporal modulation of interfacial heat consumption

When a thin film consisting of two layers of different liquids is heated from above, some oscillations of its interfaces can appear spontaneously due to the temperature dependence of interfacial tensions (Marangoni convection). These oscillations have a certain natural frequency. We investigate the possibility of changing that frequency by a periodic modulation of heating or cooling of the interface between the liquid layers. We found that in some intervals of the modulation frequency a synchronization occurs: the natural frequency of oscillations is shifted in such a way that it becomes commensurate to the external modulation frequency.

Laplace pressure versus Marangoni convection in photothermal manipulation of micro droplet

We have numerically demonstrated micro droplet migrations by photothermal manipulation, in order to investigate the driving force and accompanying flows. We focus on an oil (oleic acid) droplet in water that provides a positive temperature dependence of interfacial tension. The present direct numerical simulation employs the volume-of-fluid method and the continuum-surface-force method with consideration of temperature dependency. The driving velocity and force magnitude, which we measured quantitatively, agree with experimental and theoretical data. We have found that the dominant driving force exerted on the microdroplet is the interface normal force, i.e., the Laplace pressure, on a curved interface rather than the tangential force. The tangential component directly triggers the Marangoni convection; however, the induced flows inside the droplet are opposite between the cases of “an oil droplet in water” and “a water droplet in oil”. This may be caused by the large difference between the viscosities of water and oil.

Lowering Midline Catheter Associated Deep Vein Thrombosis's Through Change in Practice

Thermal properties of the ionic liquid (IL) 1-ethyl-3-methylimidazolium tricyanomethanide, ([EMIM][TCM]), measured by the Differential scanning calorimetry (DSC) as glass transition temperature (Tg,1), heat capacity change at glass transition temperature (ΔCp(g),1), melting temperature (Tfus), enthalpy of melting (ΔHfus), phase transition temperature (Ttr), enthalpy of phase transition (ΔtrH) and decomposition temperature (Td) were presented. The density and viscosity for the binary mixtures containing [EMIM][TCM] and thiophene at six temperatures (298.15, 308.15, 318.15, 328.15, 338.15 and 348.15 K) and ambient pressure were reported. The density and viscosity as a function of temperature were tested by an empirical second-order polynomial and by the Vogel–Fucher–Tammann equation. The density and viscosity variations with compositions were described by polynomials. Excess molar volumes were described by the Redlich–Kister polynomial expansion. Viscosity deviations were calculated and correlated by the Redlich–Kister polynomial expansions. The surface tensions of pure ionic liquid and binary mixtures of [EMIM][TCM] and thiophene were measured at atmospheric pressure at five temperatures (298.15, 308.15, 318.15, 328.15, and 338.15 K). The surface tension deviations were calculated and correlated by the Redlich–Kister polynomial expansion. The temperature dependence of interfacial tension was used to evaluate the excess surface energy, the surface enthalpy, the critical temperature, parachor and speed of sound for pure ionic liquid. These measurements have been provided to complete information of the influence of temperature on physico-chemical properties for the selected IL, which was chosen as a possible new entrainer in the separation of sulfur compounds from fuels. A qualitative analysis on these quantities in terms of molecular interactions is reported. The obtained results indicate that ionic liquid interactions with alcohols are strong dependent on the special trend of packing effects and hydrogen bonding of this ionic liquid with polar solvent.

Effect of temperature and composition on the density, viscosity surface tension and excess quantities of binary mixtures of 1-ethyl-3-methylimidazolium tricyanomethanide with thiophene

Thermal properties of the ionic liquid (IL) 1-ethyl-3-methylimidazolium tricyanomethanide, ([EMIM][TCM]), measured by the Differential scanning calorimetry (DSC) as glass transition temperature (Tg,1), heat capacity change at glass transition temperature (ΔCp(g),1), melting temperature (Tfus), enthalpy of melting (ΔHfus), phase transition temperature (Ttr), enthalpy of phase transition (ΔtrH) and decomposition temperature (Td) were presented. The density and viscosity for the binary mixtures containing [EMIM][TCM] and thiophene at six temperatures (298.15, 308.15, 318.15, 328.15, 338.15 and 348.15K) and ambient pressure were reported. The density and viscosity as a function of temperature were tested by an empirical second-order polynomial and by the Vogel–Fucher–Tammann equation. The density and viscosity variations with compositions were described by polynomials. Excess molar volumes were described by the Redlich–Kister polynomial expansion. Viscosity deviations were calculated and correlated by the Redlich–Kister polynomial expansions. The surface tensions of pure ionic liquid and binary mixtures of [EMIM][TCM] and thiophene were measured at atmospheric pressure at five temperatures (298.15, 308.15, 318.15, 328.15, and 338.15K). The surface tension deviations were calculated and correlated by the Redlich–Kister polynomial expansion. The temperature dependence of interfacial tension was used to evaluate the excess surface energy, the surface enthalpy, the critical temperature, parachor and speed of sound for pure ionic liquid. These measurements have been provided to complete information of the influence of temperature on physico-chemical properties for the selected IL, which was chosen as a possible new entrainer in the separation of sulfur compounds from fuels. A qualitative analysis on these quantities in terms of molecular interactions is reported. The obtained results indicate that ionic liquid interactions with alcohols are strong dependent on the special trend of packing effects and hydrogen bonding of this ionic liquid with polar solvent.

Phase Transition and Domain Formation in the Gibbs Adsorbed Films of Long-Chain Alcohols

The adsorption behavior of 1,1,2,2,-tetrahydroheptadecafluorodecanol (FC10OH), 1-eicosanol (C20OH), and their mixtures at the hexane solution/water interface is summarized briefly and examined from the viewpoints of interfacial tensions in the presence of domains, domain formation, and the correlation between the phase transition and the miscibility of film forming substances in the adsorbed films. The two-dimensional analogue of the Laplace equation showed that the interfacial tension is always higher in the presence of domains than that in the absence of them. The higher tendency of domain formation of FC10OH compared to C20OH is mainly ascribed to the excess Gibbs energy of mixing of fluorocarbon chains and hydrocarbon solvent being positive and to the interaction energy between domains being more stable against cohesion for FC10OH than for C20OH. The thermodynamic equations derived here suggested the heteroazeotropy in the phase diagram of adsorption and the temperature dependence of interfacial tension at the phase transition points, which are in accord with the experimental findings qualitatively.

Molecular Orientation and Multilayer Formation in the Adsorbed Film of 1H,1H,10H,10H-Perfluorodecane-1,10-diol at the Hexane/Water Interface; Temperature Effect on the Adsorption of Fluoroalkane-diol

The adsorption of 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC10diol) at the hexane/water interface was investigated by the measurement of temperature dependence of interfacial tension and the thermodynamic data analysis in order to know the effect of two hydroxyl groups at both ends of the hydrophobic chain and the rigidity of the hydrophobic chain on the adsorption of fluorocarbon alcohol at the interface. The curves of interfacial tension versus temperature and concentration show break points corresponding to the phase transitions in the adsorbed FC10diol film. The interfacial pressure versus mean area per adsorbed molecule curve shows three kinds of states connected by two discontinuous changes. The area value after the first phase transition is very close to the calculated cross-sectional area of the FC10diol molecule along its major axis, and thus the FC10diol molecules form a condensed monolayer with molecular orientation parallel to the interface. Another noticeable point is that the value after the second phase transition point decreases furthermore to 0.12 nm2, which is much smaller than the cross-sectional area of the fluorocarbon chain, 0.28 nm2, with increasing interfacial pressure. This suggests that FC10diol molecules pile spontaneously and successively form a multilayer above the second phase transition. Furthermore, the partial molar entropy and energy change of adsorption in the expanded and condensed states were evaluated and compared to those of 1H,1H,2H,2H-perfluorodecanol (TFC10OH), which orients almost perpendicular to the interface. In addition to the contact of two hydroxyl groups with hexane in the bulk solution, the results are explained by the dependence of partial molar entropy and energy at the interface on the following factors resulting from the parallel orientation of FC10diol at the interface; (a) hydrogen bonding of two hydroxyl groups with water molecules, (b) hydrogen bonding between two hydroxyl groups facing each other, and (c) the fluorocarbon chain−water contact. The adsorbed FC10diol film is stabilized by factors a and b, which overwhelm the energetic disadvantage caused by factor c. Furthermore, the entropy change of adsorption Δs in the multilayer is compared to the Δscal calculated on the assumption that the condensed monolayer piles to form the multilayer. It was suggested that FC10diol molecules are not so densely packed in the multilayer compared to the first condensed monolayer and therefore the multilayer is not simply formed by the piling of condensed monolayers.

Interfacial tension measurements and evidence of order in high-density polyethylene melts

Polyethylene (PE) is a widely used product commercially. However, our knowledge is incomplete about the properties of high-density polyethylene (HDPE) at temperatures above its melting point, where solid crystals disappear. Recently, there has been increasing evidence from rheological, differential scanning calorimetry, and NMR studies that suggests the presence of microstructural order in the bulk of PE melts. In this study, the interfacial tension of HDPE melts in contact with silicone oil was measured with a spinning drop tensiometer in the same temperature range in which phase transitions have been observed in the bulk HDPE. Anomalous temperature dependence of interfacial tension was found between 200 and 230°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4061–4067, 2003

Temperature and molecular weight dependence of interfacial tension between immiscible polymer pairs by the square gradient theory combined with the Flory-Orwoll-Vrij equation-of-state theory

Interfacial tension between immiscible polymer pairs was predicted by using a square gradient theory in conjunction with the Flory–Orwoll–Vrij equation-of-state expression for the free energy of mixing. The contact interaction parameter was determined by fitting the equation-of-state theory to experimental cloud points taken from the literature, and the square gradient coefficient was estimated from the relation derived from a scattering function. The modified square gradient theory could successfully predict both the magnitude and temperature dependence of interfacial tension between polystyrene and poly(methyl methacrylate), although no adjustable parameters were used in calculating interfacial tension. The molecular weight dependence of interfacial tension was also successfully predicted. The contribution of free volume on interfacial tension is analyzed for two systems: polystyrene/poly(methyl methacrylate) and polystyrene/poly(dimethyl siloxane) blends. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2683–2689, 1998

Prediction of interfacial tension of immisciblepolymer pairs using a square gradient theory combined with the FOV equation-of-state free energy expression

Interfacial tension between polystyrene and polybutadiene is predicted by using a square gradient theory in conjunction with the Flory-Orwoll-Vrij equation-of-state expression for the free energy of mixing. The equation-of-state interaction parameter is determined by fitting the theory to the experimental cloud points. The square gradient coefficient is also calculated by the relation derived from a scattering function. The combined theory for interfacial tension predicts a magnitude and temperature dependence of interfacial tension although no adjustable parameter is used in calculating interfacial tension. The molecular weight dependence of interfacial tension is also predicted, and well described by a relation γ = γ ∞ + CM n −z where z = 2/3 for low molecular weight species and z = 1 for higher molecular weight species.

Gibbs−Langmuir Model for Interfacial Tension of Nonideal Organic Mixtures over Water

An equation is derived for predicting the interfacial tension of nonideal organic mixtures over water. The equation combines the Gibbs and the nonideal Langmuir adsorption isotherms to describe interfacial tension in terms of organic bulk phase properties. Required inputs are pure component interfacial tension data and the organic bulk phase activity coefficients. The equation successfully predicts the experimental literature data for immiscible and partially miscible ternary systems, including aromatics, aliphatics, alcohols, and ketones. In addition, the equation is a useful tool for predicting the temperature dependence of interfacial tension.

Temperature Dependence of Interfacial Tension between Normal Organic Acids and Water

The interfacial tensions between normal organic acids and water are measured versus temperature, using either the Wilhelmy (plate) method, or the Du Noüy (ring) method. The studied liquid-liquid binary two-phase systems are aqueous mixtures of n-organic acids with a number of carbon atoms ranging from five to fourteen. In all cases the interfacial tension decreases linearly with temperature in the operating temperature range (room-80°C). Such a "normal" behavior is quite intriguing, because the interfacial tensions for the corresponding alcohol series show a parabolic-like temperature dependence, while interfacial tension is linearly increasing with temperature in the case of the corresponding amine series.

Effect of temperature on interfacial tension in kerosene—surfactant—water systems

The temperature dependence of interfacial tension in oil—surfactant—water systems was investigated to evaluate the adsorption of surfactants under superheated conditions; the adsorption under such conditions is necessary in order to provide fundamental information for discussing the superheat limit of W/O emulsions. As surfactants, Span 80 and NPE x ( x = 2, 5, and 7.5) were used. The interfacial tension was measured by the Wilhelmy method in the temperature range from 301 to 355 K. The saturation adsorption obtained from the interfacial tension data for the kerosene—water system is almost independent of temperature, while that for the n-tetradecane—water system decreases slightly with increasing temperature. The adsorption equilibrium constant is correlated as a function of temperature which contains the free energy of adsorption. From these constants, the adsorption of the surfactants under superheated conditions can be predicted.

Temperature dependence of interfacial tension of 2‐butoxyethanol/water mixtures near the lower critical point

AbstractThe pendant drop method and the capillary rise method are used to measure the interfacial tension σ of 2‐butoxyethanol (2‐C4E1)/water mixtures near the lower critical point (critical composition, mass fraction of 2‐C4E1, yc = 0.2945; critical temperature Tc(visual) = 49.41°C) as function of temperature (0.6 K ≤ (T  Tc) ≤ 18.0 K). It is found that at temperatures 0.6 K ≤ (T  Tc) ≤ 7.0 K the temperature dependence of σ is represented by a power law of the form σ = σ0ϵμ (≤ = (T  Tc(visual))/Tc) with μ = (1.26 ± 0.02) and σ0 = (8.8 ± 0.2) mN m−1. The value of μ is consistent with the theoretically expected universal value of μ = 1.26. The amplitude ratio Rσ,ζ+ = σ0(ξ0ζ+)2/kBTc calculated from the system specific values of the critical amplitude σ0 and the critical amplitude ξ0 of the correlation length of local concentration fluctuations (ξ0ζ+ = (0.44 ± 0.04) nm) leads to a value of Rσ,ξ+ = (0.383 ± 0.070). It is close to the median value of Rσ,ξ+ calculated for several one‐ and two‐component fluids from experimental data taken from the literature (Moldover, Phys. Rev. A 31, 1022 (1985); median value Rσ,ξ+ = 0.386). – The ratio of [νT/R̄(∂T/∂z)] (νT, thermophoretic velocity (Marangoni convection); (∂T/∂z, temperature gradient) for droplets of radius R̄ of a 2‐C4E1) rich phase suspended in its coexisting H2O rich phase is calculated from the data.Values of [νT/R̄(∂T/∂z)] refering conditions along the liquid/liquid coexistence curve are given.

Interfacial tension of immiscible polymer blends: temperature and molecular weight dependence

Abstract : Interfacial tensions between immiscible homopolymers are measured using an automated pendant drop apparatus, which utilizes Video Digital Image Processing techniques. A recently developed robust shape analysis algorithm is used to analyze the experimental drop profiles. The data show the effect of temperature and number average molecular weight (Mn) on the interfacial tension for the immiscible blends polystyrene-poly(methyl methacrylate), polybutadiene-poly(dimethyl siloxane) and polystyrene-hydrogenated 1,2 polybutadiene. Interfacial tension decreases linearly with temperature and increases with molecular weight. The data for all three systems can be approximated by an empirical relationship. The interfacial tension data for the latter blend system are compared with thermodynamic theories of polymeric interfaces. A square gradient theory approach, in conjunction with the Flory-Huggins expressions for the free energy of mixing, predicts a magnitude and temperature dependence of interfacial tension which are in reasonable agreement with experimental data, and does predict a molecular weight dependence which roughly follows the empirical relationship.