Influence Of Interfacial Properties Research Articles

Investigation on the effect of interface properties on compressive failure behavior of 3D woven composites through micromechanics-based multiscale damage model

In this paper, the effect of interface properties on the compressive failure behavior of 3D woven composites (3DWC) is investigated by incorporating a micromechanics-based multiscale damage model (MMDM). The correlation between the mesoscopic stress of yarns and microscopic stress of constituents is established by defining a stress amplification factor. With the microscopic stresses, the fiber breakage and matrix failure can be separately evaluated at the microscale, without assuming the yarns as transversely isotropic homogeneous materials. Especially, the interfacial debonding between yarns and matrix is also a dominant damage mode within 3DWC. Given that there is still a lack of studies on the influence of interfacial properties on the compressive failure behavior of 3DWC, it is meaningful to perform numerical parametric studies to reveal how the interface properties contribute to the damage mechanisms of 3DWC under compressions. The predicted results indicate that with the increase of interface strengths and fracture toughness, the compressive resistance of 3DWC can be significantly improved, resulting in higher strength and failure strain. Additionally, the studied 3DWCs with weak, medium and strong interfaces exhibit different damage development processes.

Prebiotic food foams stabilized by inulin and β-lactoglobulin

Inulin is a prebiotic ingredient which is increasingly used by food industry, due to its health-promoting and techno functional properties. In the present work, the effect of the addition of different concentrations of inulin (0.25, 0.5, 1, 2.5, 5, 7.5 and 10 % wt.) on the properties of food foams stabilized by 0.25 % wt. β-lactoglobulin has been studied. In this sense, the influence of inulin concentration on nanoscopic properties of β-lactoglobulin-inulin aqueous solutions has been evaluated, looking for a correlation between those properties and the macroscopic properties of the foams formed (e.g. foaming capacity and stability). From these results, it may be concluded that interfacial rheological properties of the adsorbed film control the macroscopic properties of the aerated system at lower inulin concentrations (<2.5 % wt.). However, as the properties of the continuous phase, such as viscosity, gain control over the system behaviour at higher concentrations (>2.5 % wt.), the influence of interfacial properties is hindered. Results obtained highlight the role of inulin in promoting the stabilization of the air/water interface through a protein-polysaccharide thermodynamic incompatibility as well as its thickening effect.

Global Sensitivity Analysis for the Polymeric Microcapsules in Self-Healing Cementitious Composites.

Cementitious composites with microencapsulated healing agents are appealing due to the advantages of self-healing. The polymeric shell and polymeric healing agents in microcapsules have been proven effective in self-healing, while these microcapsules decrease the effective elastic properties of cementitious composites before self-healing happens. The reduction of effective elastic properties can be evaluated by micromechanics. The substantial complicacy included in micromechanical models leads to the need of specifying a large number of parameters and inputs. Meanwhile, there are nonlinearities in input–output relationships. Hence, it is a prerequisite to know the sensitivity of the models. A micromechanical model which can evaluate the effective properties of the microcapsule-contained cementitious material is proposed. Subsequently, a quantitative global sensitivity analysis technique, the Extended Fourier Amplitude Sensitivity Test (EFAST), is applied to identify which parameters are required for knowledge improvement to achieve the desired level of confidence in the results. Sensitivity indices for first-order effects are computed. Results show the volume fraction of microcapsules is the most important factor which influences the effective properties of self-healing cementitious composites before self-healing. The influence of interfacial properties cannot be neglected. The research sheds new light on the influence of parameters on microcapsule-contained self-healing composites.

Influences of Interface Properties on the Performance of Fiber-Reinforced Asphalt Binder.

This paper presents an experimental study about the influence of interfacial properties on the performance of fiber-reinforced asphalt. In this study, four types of fiber including one fiber-reinforced plastic (FRP), two lignin fibers, and one basalt fiber are used, and also four types of asphalt: Asphalt No. 90, asphalt No. 70, one styrene-butadiene-styrene (SBS) modified asphalt, and asphalt rubber are used. The surface energy parameters of various asphalts and fibers and the shear strength of various fiber-reinforced asphalts are measured. On the basis of these measurements, the influences of surface properties of asphalt and fiber on the performance of fiber-reinforced asphalt are analyzed. The results show that the shear strength of asphalt binder can be significantly increased by adding fibers, and the reinforcement effect is closely related to the types of asphalt and fiber. It was discovered, for the same asphalt, that the basalt fiber has the best reinforcement effect, followed by the two lignin fibers, and the FRP. For the same fiber, asphalt rubber was the most reinforced, followed by the SBS modified asphalt, asphalt No. 70 and asphalt No. 90. It was also discovered, for the same asphalt, the higher the surface energy of the fiber, the better the fiber reinforcement effect. The analysis indicates a good correlation between the work of adhesion between asphalt and fiber and the effect of fiber reinforcement. The results can be used as a basis for the selection of the proper fiber-asphalt combination to improve fiber reinforcement effects.

Synthesis of TiO2/SiO2-B2O3 Ternary Nanocomposites: Influence of Interfacial Properties on their Photocatalytic Activities with High Resolution Mass Spectrometry Monitoring

An investigation on unusual interface properties of unprecedented ternary composites, formed by the inclusion of assorted proportions of B2O3 into TiO2/SiO2 structure, is conducted herein. The influences of B2O3 content and calcination temperature were evaluated. The precursor TiO2/SiO2 material was synthesized via a simple sol-gel procedure that was followed by B2O3 inclusion via maceration and calcination. The materials were fully characterized and their photocatalytic performance to degrade the Indigo Carmine dye investigated. The material prepared with a B/Ti molar ratio of 1 and at calcination temperature of 350 °C (B1-350) showed the best performance, with a superior photocatalytic activity than that of commercial TiO2. The presence of B2O3-TiO2-SiO2 interfaces in the structure of such material was of critical importance in producing a material with these attractive features. Finally, high resolution mass spectrometry monitoring allowed for the characterization of the main degradation products formed under these conditions.

Influence of interfacial properties on Ostwald ripening in crosslinked multilayered oil-in-water emulsions

The influence of interfacial crosslinking, layer thickness and layer density on the kinetics of Ostwald ripening in multilayered emulsions at different temperatures was investigated. Growth rates of droplets were measured by monitoring changes in the droplet size distributions of 0.5% (w/w) n-octane, n-decane, and n-dodecane oil-in-water emulsions using static light scattering. Lifshitz–Slyozov–Wagner theory was used to calculate Ostwald ripening rates. A sequential two step process, based on electrostatic deposition of sugar beet pectin onto fish gelatin or whey protein isolate (WPI) interfacial membranes, was used to manipulate the interfacial properties of the oil droplets. Laccase was added to the fish gelatin–beet pectin emulsions to promote crosslinking of adsorbed pectin molecules via ferulic acid groups, whereas heat was induced to promote crosslinking of WPI and helix coil transitions of fish gelatin. Ripening rates of single-layered, double-layered and crosslinked emulsions increased as the chain length of the n-alkanes decreased. Emulsions containing crosslinked fish gelatin–beet pectin coated droplets had lower droplet growth rates (3.1±0.3×10−26m3/s) than fish gelatin-stabilized droplets (7.3±0.2×10−26m3/s), which was attributed to the formation of a protective network. Results suggest that physical or enzymatic biopolymer-crosslinking of interfaces may reduce the molecular transport of alkanes between the droplets in the continuous phase.

Influence of Interfacial Properties on Crack Propagation in Fiber‐Reinforced Polymer Matrix Composites

AbstractDynamic crack propagation routes in composites were investigated using numerical methods. The interfacial strength was characterized by means of the interfacial nodal constrained failure. Five different micro‐damage modes around a broken fiber and the corresponding stress/strain curves were obtained with the interfacial strength increasing. It was proved that the shear stress concentration region appears to be different as the interface varying from weak to strong and that the recovery of fiber load‐supporting with a strong interface is better than that with a weak interface. Experimental work has been done and the available results agree well with corresponding simulation results.magnified image

Theoretical Analysis of Factors Affecting the Formation and Stability of Multilayered Colloidal Dispersions

A mathematical analysis of the major factors influencing the formation and stability of colloidal dispersions containing spherical particles surrounded by multilayered polymeric interfacial membranes formed by the layer-by-layer electrostatic deposition technique is carried out. The mathematical model assumes that (i) the colloidal dispersion initially consists of a mixture of electrically charged monodisperse spherical particles and oppositely charged polymer molecules, (ii) the adsorption of polymer molecules to the particle surfaces is diffusion-limited, and (iii) the dominant particle-particle collision mechanism is Brownian motion. This approach was used to produce stability maps that highlight conditions under which bridging flocculation, multilayer formation, or depletion flocculation occurs. The stability maps are derived from calculations of the critical polymer concentrations required to (i) saturate the particle surfaces (C(Sat)), (ii) ensure that polymer adsorption is faster than particle collisions (C(Ads)), and (iii) promote depletion flocculation (C(Dep)). In addition, the influence of interfacial properties on the stability of multilayer colloidal dispersions was assessed by calculating the colloidal interactions between the coated particles (i.e., van der Waals, electrostatic, steric, and depletion). These calculations indicated that the major factors are the interfacial charge and composition rather than the interfacial thickness. This article provides useful insights into the factors affecting the formation of stable multilayer colloidal dispersions.

Influence of interfacial properties on perfluorocarbon/aqueous emulsion stability

Perfluorocarbon liquid emulsion systems were prepared containing lecithin, mixtures of synthetic phospholipids, cholesterol, cholesterol oleate and Pluronic F68 as emulsifiers. Attempts were made to correlate the stability of the various emulsion systems with their interfacial tension and charge properties. Due to batch to batch variability in the composition of natural egg yolk lecithin, a standard phospholipid mixture was formulated to represent lecithin in these studies. This standard mixture was composed of synthetic analogs of the major molecular species present in lecithin (dioleoyl phosphatidylcholine, dipalmitoyl phosphatidylcholine and dipalmitoyl phosphatidylethanolamine). Egg yolk lecithin and Pluronic F68 were studied for comparison with the standard phospholipid mixture. Analogs of the minor phospholipid species present in lecithin and other surfactant systems were investigated as additives to the standard phospholipid mixture as follows: phosphatidic acid, phosphatidylinositol, phosphatidylserine lysophosphatidylcholine, lysophosphatidylethanolamine, cholesterol, cholesterol oleate and Pluronic F68. Dynamic interfacial tension was determined using a Teflon Wilhelmy plate method (these data were reported in a previous publication). Interfacial charge was determined by microelectrophoresis of the emulsion droplets. Emulsions were prepared using an ultrasonic probe. Emulsion stability was determined by droplet size analysis as a function of time using photon correlation spectroscopy and Coulter analysis. Both thermal stability kinetic studies and sterilization stability studies were conducted. A novel method of assessment of emulsion stability is reported, involving the assignment of points to each emulsion system based on various droplet size parameters.

P264 the influence of interfacial properties of emulsion stabilizers on emulsion stability

P264 the influence of interfacial properties of emulsion stabilizers on emulsion stability

Influences of Interfacial Properties on High-Performance Concrete Composites

AbstractThere is a strong motivation to study the interfacial properties of concrete composites because the interfacial region is often the phase where fracture first develops. The aim of this study is to understand phenomena which are unique at high-performance concrete composite interfaces, and how these influence the bulk properties of a concrete composite. Since processes at interfaces must be considered over a range of scales varying from the atomic to the macroscopic, multidisciplinary research approaches are desirable. Model cement/rock (aggregate) and matrix/fiber interaction experiments were carried out. Morphology and microstructure of interfacial regions among mortar/rock, and fiber/matrix were examined utilizing SEM. Computer image analysis performed along a perpendicular to the interface revealed compositional and physical irregularities. The variations in the volume of pores adjacent to interface zones are documented and supported by microscopic observation. The influences of interfacial properties on concrete composite strength and durability are discussed, and influences of fibers on the fracture and fracture resistance behavior are also discussed. Analyses of debonding along interfaces are used to define the role of debonding in fiber-reinforced concrete composites.

Influences of Interfacial Properties on High-Performance Concrete Composites

AbstractThere is a strong motivation to study the interfacial properties of concrete composites because the interfacial region is often the phase where fracture first develops. The aim of this study is to understand phenomena which are unique at high-performance concrete composite interfaces, and how these influence the bulk properties of a concrete composite. Since processes at interfaces must be considered over a range of scales varying from the atomic to the macroscopic, multidisciplinary research approaches are desirable. Model cement/rock (aggregate) and matrix/fiber interaction experiments were carried out. Morphology and microstructure of interfacial regions among mortar/rock, and fiber/matrix were examined utilizing SEM. Computer image analysis performed along a perpendicular to the interface revealed compositional and physical irregularities. The variations in the volume of pores adjacent to interface zones are documented and supported by microscopic observation. The influences of interfacial properties on concrete composite strength and durability are discussed, and influences of fibers on the fracture and fracture resistance behavior are also discussed. Analyses of debonding along interfaces are used to define the role of debonding in fiber-reinforced concrete composites.

Agglomeration of Coals of Different Rank Using Mixtures of Oils

The influence of interfacial properties in oil agglomeration of coal has been experimentally studied by testing four coals of different rank using a series of agglomerating agents obtained by mixing, in variable proportions, two basic commercial oils having distinct densities. The results show that oil agglomeration is always more efficient on coals of higher rank for which fuel recovery can be increased by using suitable mixtures of basic oils. The improvement in recovery is much more marked in the case of subbituminous coals. The experimental results are discussed and a scientific interpretation is given.

Role of interfacial properties on the motion and deformation of capsules in shear flow

The influence of interfacial properties on the dynamics of a capsule freely suspended in viscous liquid subjected to flow is assessed. First, the case of a liquid-liquid interface considered: experimental evidence and theoretical models show that the drop deformat depends on the type of flow, the internal to external viscosity ratio and the capillary number which measures the ratio between surface tension and viscous forces. Burst of the drop predicted to occur when the normal stress equilibrium cannot be satisfied everywhere on interface. Next, we consider the case of capsules, which are liquid drops enclosed by a so depormable interface. From experiment and theoretical models, they are known to deform and to burst in some cases. Their motion depends on essentially the same parameters as liquid drops, but different interfacial constitutive laws lead to different types of deformation and motion.

Lifetime of supported liquid membranes: the influence of interfacial properties, chemical composition and water transport on the long-term stability of the membranes

The permeability coefficients of some metal species through selected supported liquid membranes (SLM) have been measured over extended periods of time, in the presence and absence of osmotic pressure gradients. The composition of the SLMs was varied in such a way to obtain membranes with variable interfacial properties. The interfacial tensions, viscosities, contact angles and water solubilities in the organic phases of the various liquid membranes were measured. The ability of these SLMs to transport water under the influence of osmotic pressure gradients of different magnitude was also measured. In this way correlations were established among the following factors: the lifetime of the SLMs, their interfacial and water extraction properties, the concentrations of the feed and strip solutions adjacent to the SLM and the ability of the SLM to transport water. The results of long-term operation of several types of SLMs indicate that they are relatively stable when the osmotic pressures of the feed and strip solutions are approximately equal, but become increasingly unstable as the difference between the osmotic pressures of the feed and strip solutions increases. In addition, the rate at which water is transported through the SLMs under the influence of a given osmotic pressure difference is inversely related to membrane lifetime. The following mechanism of water transport through SLMs was proposed: (i) in presence of an osmotic pressure gradient water tends to flow through the organic-filled pores of the SLM, providing the organic phase can appreciably solubilize water; this initial water flow can be imagined as the diffusion of water molecules through a stationary organic diluent; (ii) when the amount of flowing water becomes massive and the SLM is easily wetted by the aqueous phases, the organic phase is eventually displaced from the support pores and replaced by water; at this point the membrane behaves as a semipermeable diaphragm containing water-filled micropores and its ability to perform carrier-mediated coupled transport of metal species is completely lost.

Influence of interfacial properties on the modes of propagation of a gravity wave on the surface of a liquid

The evolution of monochromatic waves in an interfacial medium separating a liquid and a gas is investigated. Two viscosity effects are found and studied: a dispersive effect and a damping effect. The introduction of a constant tension tends to eliminate the viscous effects. Finally, if the interface is similar to a material film and is characterized by an elastic-type behavior, the effects of inertia and elasticity film are presented.

Influence of interfacial properties on the kinetics of precipitation and precipitate coarsening in aluminium-silver alloys

The lengths and thicknesses of hexagonal Ag 2Al precipitates in AI-Ag were studied under two conditions; firstly during free precipitate growth in supersaturated solid solutions before soft impingement and secondly during Ostwald Ripening. Measurement of the lengths and thicknesses of freely growing precipitates by optical microscopy and replica electron microscopy showed agreement with the kinetics expected for diffusion controlled growth of plate-like precipitates with the observed very large aspect ratios. However a study of the precipitates at the start of precipitation by transmission electron microscopy (TEM) showed initial inhibition of the thickening reaction which led to the large aspect ratios observed. This latter observation supports Aaronson's theory of precipitate morphology. The study of Ostwald Ripening showed two effects: firstly the retention of the large- non-equilibrium, aspect ratios and secondly a rapid increase of the mean precipitate length. A model, that successfully accounted for these observations was developed. The model was based on two assumptions, inhibited thickening at the low supersaturations of Ostwald Ripening, but diffusion limited lengthening.

The influence of interfacial properties on the stability of black lipid films

By considering the interfaces between the lipid phase (O) present in the border of a black lipid film, the solid (S) supporting the film, and the aqueous phase (W) present on both sides of the film, a stability condition for the film is derived from the Young-Dupré equation. This condition expresses that, in a stable film, the film tension must balance the difference between the tensions of the S/W and the S/O interfaces. It is shown how this difference can be obtained experimentally by measurements of the contact angles and surface tensions present in sessile drops of water and of oil on the solid material. Such measurements have been carried out with mixtures of glycerol mono- and dioleate on different solids (mainly, Teflon and polyethylene). The stability of black films, prepared according to Montal and Müller ( Proc. Nat. Acad. Sci. USA 69, 3561 (1972) from two monolayers, has been examined with the same lipid and solid materials. For these systems it is found that stable bilayers can be formed only with those lipid mixtures that, according to the derived theoretical predictions, should stable films. The poor stability of black phospholipid films prepared by the monolayer technique can be explained qualitatively with the same theory.