Measurement Of Interfacial Properties Research Articles

Optimized interfacial tension and contact angle for spontaneous imbibition in low-permeable and oil-wet sandstone cores with light crude oil

Spontaneous imbibition is an important phenomenon of fluid transports in porous media, particularly in liquid environment with a certain range of interfacial tension and wettability. Meanwhile, the spontaneous imbibition could be enhanced with the additions of surfactants, through modifying the oil–water interfacial tension (IFT) and wettability. However, ultra-low IFT impairs the capillary pressure. Hence, appropriate ranges of the IFT and contact angle (CA), though lacking adequate investigations, are key to optimizing spontaneous imbibition. Here, a series of physical experiments were conducted to evaluate the spontaneous imbibition efficiency of surfactant solutions with wide-range IFTs (10−3-101 mN/m) in the porous media of permeability 11 mD, through designed interfacial property measurements with different surfactant concentrations. Besides, the inverse Bond number was employed to determine the optimized interfacial properties during the imbibition. Overall, the best imbibition-induced hydrocarbon recovery is reached at oil viscosity of 25.26 mPa·s, an IFT of 0.1–0.2 mN/m and a CA of 70-80°.

A Classical Molecular Dynamics Study of the Effect of the Atomic Force Microscope Tip Shape, Size and Deformation on the Tribological Properties of the Graphene/Au(111) Interface

Atomic force microscopes are used, besides their principal function as surface imaging tools, in the surface manipulation and measurement of interfacial properties. In particular, they can be modified to measure lateral friction forces that occur during the sliding of the tip against the underlying substrate. However, the shape, size, and deformation of the tips profoundly affect the measurements in a manner that is difficult to predict. In this work, we investigate the contribution of these effect to the magnitude of the lateral forces during sliding. The surface substrate is chosen to be a few-layer AB-stacked graphene surface, whereas the tip is initially constructed from face-centered cubic gold. In order to separate the effect of deformation from the shape, the rigid tips of three different shapes were considered first, namely, a cone, a pyramid and a hemisphere. The shape was seen to dictate all aspects of the interface during sliding, from temperature dependence to stick–slip behavior. Deformation was investigated next by comparing a rigid hemispherical tip to one of an identical shape and size but with all but the top three layers of atoms being free to move. The deformation, as also verified by an indentation analysis, occurs by means of the lower layers collapsing on the upper ones, thereby increasing the contact area. This collapse mitigates the friction force and decreases it with respect to the rigid tip for the same vertical distance. Finally, the size effect is studied by means of calculating the friction forces for a much larger hemispherical tip whose atoms are free to move. In this case, the deformation is found to be much smaller, but the stick–slip behavior is much more clearly seen.

Differences in the Interfacial Mechanical Properties of Thiophosphate and Argyrodite Solid Electrolytes and Their Composites.

Interfacial mechanics are a significant contributor to the performance and degradation of solid-state batteries. Spatially resolved measurements of interfacial properties are extremely important to effectively model and understand the electrochemical behavior. Herein, we report the interfacial properties of thiophosphate (Li3PS4)- and argyrodite (Li6PS5Cl)-type solid electrolytes. Using atomic force microscopy, we showcase the differences in the surface morphology as well as adhesion of these materials. We also investigate solvent-less processing of hybrid electrolytes using UV-assisted curing. Physical, chemical, and structural characterizations of the materials highlight the differences in the surface morphology, chemical makeup, and distribution of the inorganic phases between the argyrodite and thiophosphate solid electrolytes.

Synthesis of phospholipid based zwitterionic surfactant from coconut oil source and characterization of their interfacial, antiseptic and antiviral properties

In this study, a phospholipid based zwitterionic surfactant CDP-W (cocamidopropyl propylene glycol (PG)-dimonium chloride phosphate) was synthesized from coconut oil source and the structure of the prepared surfactant CDP-W was identified by FT-IR, 1H NMR and 13C NMR analysis. Interfacial property measurements such as CMC, static and dynamic surface tensions, interfacial tension, foamability and foam stability have revealed that CDP-W surfactant possesses better surfactant activity and more effective in lowering surface free energy than CAPB (cocamidopropyl betaine) which is a zwitterionic surfactant widely used in cosmetics, personal products and household products. Environmental compatibility tests such as biodegradability, oral toxicity, skin irritation and eye irritation showed that CDP-W surfactant is easily biodegradable, non-toxic, mild and non-irritating to skin and eye. In particular, CDP-W reveals excellent antiseptic and antiviral properties without using any additional preservative and disinfectant, suggesting that CDP-W surfactant can replace CAPB in the formulation of cosmetics, personal products and household products.

Measurement of Film-Elastomer Interface Adhesion by Continuous Buckling.

Measurement of interfacial properties between thin films and elastomers is investigated. As a prototype, the interface adhesion between a graphite nanoflake and an elastic polymer is determined by topography imaging of the induced graphite buckles using atomic force microscopy. A theoretical analysis is carried out to establish the relationship among interface adhesion, elastic strain energy, and buckle surface area. The strain energy of the graphite is obtained by employing an elastic plate deflection theory. To introduce the buckles, different methods are applied, including thermal contraction, bending, and stretching, and different substrate materials, namely, polydimethylsiloxane and polystyrene, are used. The uncertainty in measuring the interface adhesion is discussed. These investigations provide a promising approach to characterize the interfacial properties of multilayer samples.

Measurement of interfacial properties among fluids by micro-droplets observation

Shapes of 30 micron-droplets floating on liquid surface are observed. When a microdroplet ejected from an inkjet nozzle impinges on the immiscible liquid surface, we can observe the stable shape of the floating droplet after 200 μs from the touchdown. We observed the shapes of the upper and lower sides of the droplet simultaneously with two microscopes and analyzed the profile of the droplet. Considering the line tension acting on the three-phase contact line, we succeeded in explaining the experimental shape of the floating microdroplet on the liquid surface.

Interfaces of Gas-Aerosol Particles: Relative Humidity and Salt Concentration Effects.

The growth of aerosol particles is intimately related to chemical reactions in the gas phase and particle phase and at gas-aerosol particle interfaces. While chemical reactions in gas and particle phases are well documented, there is very little information regarding interface-related reactions. The interface of gas-aerosol particles not only facilitates a physical channel for organic species to enter and exit but also provides a necessary lane for culturing chemical reactions. The physical and chemical properties of gas-particle interfaces have not been studied extensively, nor have the reactions occurring at the interfaces been well researched. This is mainly due to the fact that there is a lack of suitable in situ interface-sensitive analytical techniques for direct measurements of interfacial properties. The motivation behind this research is to understand how interfaces play a role in the growth of aerosol particles. We have developed in situ interface-specific second harmonic scattering to examine interfacial behaviors of molecules of aerosol particles under different relative humidity (RH) and salt concentrations. Both the relative humidity and salt concentration can change the particle size and the phase of the aerosol. RH not only varies the concentration of solutes inside aerosol particles but also changes interfacial hydration in local regions. Organic molecules were found to exhibit distinct behaviors at the interfaces and bulk on NaCl particles under different RH levels. Our quantitative analyses showed that the interfacial adsorption free energies remain unchanged while interfacial areas increase as the relative humidity increases. Furthermore, the surface tension of NaCl particles decreases as the RH increases. Our experimental findings from the novel nonlinear optical scattering technique stress the importance of interfacial water behaviors on aerosol particles in the atmosphere.

Interfacial properties pertinent to W/O and O/W emulsion systems prepared using polyaromatic compounds

Establishing interfacial science to understand molecular mechanisms of stabilizing water in heavy crude oil (W/O) emulsions is challenging due to non-transparent nature of crude oil even in diluted systems, as most of the interfacial property measurements are based on visualization of the experimental systems. This study investigates whether interfacial properties measured using transparent O/W emulsion systems could be used to understand the stability of W/O emulsion systems. With the same chemistry of interfacially active polyaromatic compounds (C5Pe and C5PeC11) in xylene as the model oil, the interfacial tension, crumpling ratio, dilatational rheology and coalescence time of W/O and O/W systems were measured. For less surface active C5PeC11, the interfacial tensions for W/O and O/W systems were similar. For more surface active C5Pe, the interfacial tension of the W/O system was lower than that of the O/W system, while the film rigidity and viscoelasticity of the W/O system were higher than that of the O/W system. At low C5Pe concentration, the coalescence time for the W/O system was lower than that for the O/W system with the coalescence time for the W/O system being higher at higher C5Pe concentrations. The results reveal that even though the interfacial properties measured using reverse O/W system exhibit similar qualitative trends, care should be taken when quantitatively studying W/O emulsions using interfacial property measurements of the O/W system due to the difference in most of the interfacial properties measured using the W/O and O/W systems.

A Novel Experimental Method to Generate Steam Within a Small Optical Cell for Measuring Interfacial Properties

Steam injection in heavy oil reservoirs does not only change the fluid properties, but also affects the interfacial tension of aqueous phase/hydrocarbon and the wettability of sand/hydrocarbon systems. Understanding the alteration of those properties is crucial for a successful steam injection, and it is expected to play an important role in heavy oil recovery from sands. However, studies on the measurements of interfacial properties of steam, heavy oil, and sand systems have not been well documented in the literature. This paper describes a new experimental technique and procedure which have been developed for generating steam within a small optical cell at high saturated pressure and temperature conditions. After that, image processing technique was applied to measure the interfacial tension of heavy oil/steam and the contact angle of heavy oil/steam/quartz systems. They have several advantages which are fast, relatively cheap and reliable. They potentially would have a wide range of applications in steam injection such as measuring the rock wettability, examining the effects of steam acidity and steam quality, and optimization for the purposes of prevention and/or reduction in damages to the formation. The experimental results indicate that steam injection has caused the alteration of interfacial properties. Interfacial tension measured in steam/heavy oil systems tends to decrease, while contact angle measured in quartz/heavy oil/steam systems tends to increase at saturated temperature and pressure conditions. As the aging time increases, the quartz’s wettability changes from mixed-wet to more oil-wet.

A robust nanoscale experimental quantification of fracture energy in a bilayer material system.

Accurate measurement of interfacial properties is critical any time two materials are bonded--in composites, tooth crowns, or when biomaterials are attached to the human body. Yet, in spite of this importance, reliable methods to measure interfacial properties between dissimilar materials remain elusive. Here we present an experimental approach to quantify the interfacial fracture energy Γi that also provides unique mechanistic insight into the interfacial debonding mechanism at the nanoscale. This approach involves deposition of an additional chromium layer (superlayer) onto a bonded system, where interface debonding is initiated by the residual tensile stress in the superlayer, and where the interface can be separated in a controlled manner and captured in situ. Contrary to earlier methods, our approach allows the entire bonded system to remain in an elastic range during the debonding process, such that Γi can be measured accurately. We validate the method by showing that moisture has a degrading effect on the bonding between epoxy and silica, a technologically important interface. Combining in situ through scanning electron microscope images with molecular simulation, we find that the interfacial debonding mechanism is hierarchical in nature, which is initiated by the detachment of polymer chains, and that the three-dimensional covalent network of the epoxy-based polymer may directly influence water accumulation, leading to the reduction of Γi under presence of moisture. The results may enable us to design more durable concrete composites that could be used to innovate transportation systems, create more durable buildings and bridges, and build resilient infrastructure.

Bubble in flow field: A new experimental protocol for investigating dynamic adsorption layers by using capillary pressure tensiometry

For many years the model of a dynamic adsorption layer (DAL) is well established as explanation for the behavior of rising bubbles in surfactant solutions. This model explains the velocity profile and the evolution of the shape of a rising bubble based on the hypothesis of the balance between the drag force and the structure of the adsorbed layer governed by Marangoni convection. However, direct measurements of interfacial properties of the bubble during rising are a real challenge. Here we present a new experimental protocol called “bubble in flow field” suitable for direct measurements of dynamic interfacial properties of a bubble surface using the capillary pressure tensiometry under liquid flow conditions. The experimental results for pure water demonstrate the applicability of the technique for measuring the surface tension of bubbles in a liquid flow field. The operational conditions including capillary tip geometry, liquid flow rate, bubble size and distance of the flow outlet to the bubble pole are optimized experimentally to achieve significant flow effects on a fixed bubble, while surface tension measurements are still reliable. The results for surfactant solutions (C12DMPO and CTAB) indicate respective effects depending on the flow conditions around a freshly formed bubble and evidence the formation of a dynamic adsorption layer. The adsorption equilibrium state is reached faster for higher liquid flow rates. However, the effect of the flow field is negligible on pre-aged bubble surfaces, i.e. no net desorption effects caused by the liquid flow are observed.

A Microtensiometer To Probe the Effect of Radius of Curvature on Surfactant Transport to a Spherical Interface

Diffusion of surfactant to a spherical interface depends on the radius of curvature of the interface; the smaller the radius of curvature is, the faster the dynamics. This paper presents and validates an experimental apparatus, denoted a "microtensiometer", to study the dependence of surfactant dynamics on radius of curvature. Dynamic surface tension is monitored for a range of bubble radii from 17 to 150 microm, and the dynamics are compared with those obtained using the classic pendant drop experiment for a nonionic surfactant at the air-water interface. Experiments reveal that dynamic surface tension follows a diffusion-limited scaling, in which radius of curvature is a key parameter. Despite the clear scaling behavior of the experimental equilibration time, the full dynamic curve for an initially clean interface cannot be predicted by a diffusion-limited transport model using the molecular diffusion coefficient and a single isotherm. However, the same model is shown to correctly predict compression-expansion experiments. Aside from elucidation of surfactant transport, this device provides a tool for rapid measurements of interfacial properties using a significantly lower volume of sample than current methods.

Wetting phenomena in oil sand systems and their impact on the water-based bitumen extraction process

The highly efficient and economically feasible technology for bitumen recovery from U.S. oil sands using a water-extraction approach was developed at the end of the last century. This water-based bitumen extraction process has been optimized based on observations and analysis of microscopic mechanisms of bitumen release from oil sands and the bitumen transfer to a froth product as well as measurements of interfacial properties of bitumen. The wetting mechanisms that occur in the diluent-assisted water-based processing of U.S. oil sands include bitumen film rupture and recession on sand grains and bitumen transfer to nucleated and injected gas bubbles. These mechanisms are reviewed in this contribution.

Comparison between modeling and experimental measurements of interfacial properties

This paper provides two examples of computer simulation of interfacial phenomena, performed for the purpose of aiding the progress of experimental studies. In both cases, the modeling was performed by Monte Carlo methods, in conjunction with semi-empirical density functional type potentials. In the first example, simulations of compositional surface phase transitions in Cu–Ag alloys were performed. These simulations were very useful in guiding experiments away from (1 0 0)- to (1 1 1)-oriented Cu–Ag single crystals, where the sought-after transitions were eventually observed. In the second example, modeling was used to obtain quick estimates of the absolute values of Pb/Al interfacial energies. When measurements were eventually performed, the computed values were found to overestimate the measured Pb/Al(1 1 1) interfacial energy by about a factor of 3. Beyond those two examples, what we have learned from our own efforts at modeling alloy surface and interface phenomena with semi-empirical density functional type potentials, is that this type of modeling rarely produces quantitatively reliable predictions of compositions or energies. Nevertheless, some of the qualitative features of the predictions can often provide valuable insights for planning or interpreting experiments.

Light Atom Sensitivity of Quantitative HREM

Introduction: Modern TEM/STEM instruments with field emission gun and various analytical equipment allow the measurement of interfacial properties by a range of modes and techniques without exchanging the specimen. It is therefore useful to think of a criterion to assess the sensitivity of each technique, e.g. for the location of light atoms, by a commonly applicable formula.Sensitivity measures: A “quantitative” TEM experiment is defined here as consisting of a digital comparison (e.g. via data difference or cross correlation) between experimental (E) and simulated (S) microscopy signal. The matching quality R = f(E,S) is to be optimised (minimum for data difference, maximum for cross correlation). The target quantity of the Q-TEM experiment is assumed to be the location or occupancy of a light atomic column in projection surrounded by heavier atoms in the core of an interface making use of dynamical enhancement effects.

Measurements of interfacial properties with the axisymmetric bubble-shape analysis technique: effects of vibrations

We studied the effects of perturbation by vibration on the surface tension and surface area data obtained with the bubble-profile fitting method, using a typical laboratory apparatus. Examining an air bubble issuing downwards from a capillary tip, inside a vessel containing water, we report experimental observations about the effect of multifrequency vibrations on the bubble profile, either in the non-resonance or in the resonance condition, for some normal oscillation modes of the bubble and of the liquid body. Experimental results are given with regard to multifrequency-vibration disturbances on determination of the static surface tension of the liquid and the geometrical properties of the bubble, as a function of acceleration amplitude of vibration. Also, illustrative experimental observations are presented of the dynamic surface tension response to a surface area change, for a surfactant solution, under the action of vibration motion. In the frequency–acceleration plane, we show negligible effects on surface data in the 0–100 Hz and 0–5m g domain, for the geometrical configuration examined and the overall experimental system. The tolerability limit appears at 10m g acceleration, where excitation of the bubble resonance oscillation may occur with significant amplitude. The conclusions are also useful for estimation of the vibration effects in different configurations.

Axisymmetric Drop Shape Analysis: Computational Methods for the Measurement of Interfacial Properties from the Shape and Dimensions of Pendant and Sessile Drops

State-of-the-art axisymmetric drop shape analysis (ADSA) techniques for the computation of interfacial tensions and contact angles by fitting the Laplace equation of capillarity to the shape and dimensions of pendant and sessile drops are presented. More accurate, efficient, and reliable versions of the technique for the measurement of contact angles from the volume and diameter of sessile drops [axisymmetric drop shape analysis—diameter (ADSA-D)] and for interfacial tension measurements from a series of arbitrary profile coordinates of sessile and pendant drops [axisymmetric drop shape analysis—profile (ADSA-P)] have been developed. Advanced numerical methods have been used to improve the numerical stability and global convergence, for more accurate results and a wider range of applicability of the methods. A new technique called axisymmetric drop shape analysis—height and diameter (ADSA-HD) has been developed to estimate interfacial tensions from the height and diameter of sessile and pendant drops. Numerical simulations using numerically generated drop profiles were used to evaluate the accuracy and applicability of the methods.

Analytical in situ characterization of chemical reactivities at interfaces in aqueous systems

Abstract Local chemical reactivities influence strongly various processes at solid surfaces in the marine environment. Therefore, in situ measurements of interfacial properties with spatial resolution are needed. Such investigations can be performed with a new microscopic technique, the scanning electrochemical microscopy (Bard et al., 1989). Applications of this method to study interfaces such as carbon/aqueous solution and polymer structures in solution are reported. A home-made electrochemical microscope allowed the in situ characterization of permeation properties of surface layers at carbon.

Use of mixed surfactants to improve the transient interfacial tension behaviour of heavy oil/alkaline systems

AbstractThe objective of this study was to identify suitable combinations of additives to aqueous alkaline formulations for the potential recovery of Saskatchewan heavy crude oil. A previously developed strategy was applied to screen various additive combinations consisting of three commercial petroleum sulfonate surfactants and two commercial lignosulfonate surfactants. The selection of the additives was based on a large number of physical and interfacial property measurements in conjunction with phase stability tests at different temperatures. The resulting ternary formulations, labelled here as Mixed‐Surfactant‐Enhanced Alkaline (MSEA) systems, were very successful in reversing the trend of increasing interfacial tension with time that characterizes additive‐free alkaline/crude oil systems. This success came at the expense of initial IFT values that were considerably higher than those exhibited by the corresponding additive‐free alkaline solutions. However, at higher temperatures (65 °C), these ternary MSEA formulations were capable of generating very low IFT values against the crude oil (in the range of 5 × 10−2 to 10−1 mN/m), which suggests that they could be suitable candidates for commercial exploitation of heavy oil recovery processes.

Measurement of Interfacial Properties for Aluminum and Titanium Matrix Alloy Composites Manufactured by Vacuum Plasma Spray

Continuous fiber silicon carbide/titanium and aluminum matrix composite monolayers were tested by means of an indentation technique to measure the interfacial shear strength. Experimental results were interpreted using two analytical models and compared to results of other researches in order to evaluate the interface quality obtained with a vacuum plasma spray fabrication method. The separate contribution of chemical bond and friction to the mechanical shear strength of the fiber-matrix interface is discussed. For aluminum matrix composites, the interface strength is mainly controlled by frictional force. For titanium matrix composites, chemical bond plays a primary role. The vacuum plasma spray process used needs further optimization work, but it is a very promising fabrication method for continuous fiber reinforced metal matrix composites.