Interfacial behaviour

Yang, J.M., Jeng, S.M. and Yang, C.J. (1991). Fracture mechanisms of fiber reinforced titanium alloy matrbi composites. Part I. interfacial behaviour. Mater. Sci. Eng. AI38, 155-167. 

Chandra, N. and Ananth, C.R. (1995). Analysis of interfacial behaviour in MMCs and IMCs by the use of thin-slice push-out test. Composites Sci. Technol. 54, 87-110. 

Toxler, L., Wipff, G. 1998. Interfacial behaviour of ionophoric systems Molecular dynamics studies on 18-crown-6 and its complexes at the water-chloroform interface. Anal. Sci. 14 43-56. 

Compared to bulk polymer mixtures, the interfacial behaviour of polymer blends is essentially different [341]. The demixing process in thin films is strongly affected by the thin film confinement and the interfacial interactions of the blend components with the confining phases (e.g., substrate and air). Even in the one-phase region of the phase diagram, preferential segregation of the components at one of the interfaces leads to a certain composition profile as a function of the distance from the free surfaces and the substrate plane [342,343]. In the... 

In these past 10 years, it has been demonstrated that the TR-QELS method is a versatile technique that can provide much information on interfacial molecular dynamics [1-11]. In this chapter, we intend to show interfacial behaviour of molecules elucidated by the TR-QELS method. In Section 3.2, we present the principle, the historical background and the experimental apparatus for TR-QELS. The dynamic collective behaviour of molecules at liquid/liquid interfaces was first obtained by improving the time resolution of the TR-QELS method. In Section 3.3, we present an application of the TR-QELS method to a phase transfer catalyst system and describe results on the scheme of the catalytic reactions. This is the first application of the TR-QELS method to a practical liquid/liquid interface system. In Section 3.4, we show chemical oscillations of interfacial tension and interfacial electric potential. In this way, the TR-QELS method allows us to analyze non-linear adsorption/desorption behaviour of surfactant molecules in the system. 

D. Lexa and J. M. Saveant, Supramolecular Effects in the Redox and Coordination Chemistry of Superstructured Iron Porphyrins, in Redox Chemistry and Interfacial Behaviour of Biological Molecules , eds.G. DryhurstandK. Niki, Plenum, New York, 1988, p. 1. 

Adhesives form an important class of materials entirely consisting of polymers. In this application, both the bulk mechanical properties of the polymers and their Interfacial behaviour determine the performance. Strong adsorption is required for proper adhesive joints. Small amounts of low-molecular-weight impurities may adversely affect the segment adsorption energy. A fundamental understanding of such competitive adsorption phenomena is mandatory for improving these products. 

For these copolymers, a distinction has to be made between random and block copolymers. These two classes may differ considerably in their Interfacial behaviour. Most of the trends discussed for homopolymer adsorption apply also to random copolymers, so that the insights presented in this chapter can still serve as a guide when dealing with practical systems in which, so far, mostly random copolymers are used. Block copolymers are potentially very interesting for many speciflc applications but are not yet applied on a large scale. We return to these more sophisticated systems in Volume V. 

Polymer-polymer interfaces are an important area of study since the interfacial behaviour is fundamental to the bulk properties of the system. This is particularly true when two or more polymers are mixed to form a blend, but the interface also plays a dominant role in areas such as adhesion, welding, surface wetting and mechanical strength. To understand fully polymer behaviour in such applications, the interface must be characterised at a microscopic level. Through deuterium labelling the interface between otherwise indistinguishable polymers can be studied, and neutron reflectivity provides unprecedented detail on interfacial width and shape. In addition to the inherent interdiffusion between polymers at a polymer-polymer interface, the interface is further broadened by thermally driven capillary waves. Capillary waves... 

R. Miller, G. Loglio, U. Tesei and K-H. Schans, Surface Relaxations as a Tool for Studying Dynamic Interfacial Behaviour, Adv. Colloid Interface Set 37 (1991) 73-96. 

Fuerstenau, D.W. and Shibata, J., On using electrokinetics to interpret the flotation and interfacial behaviour of manganese dioxide, Int. J. Miner. Process., 57, 205,1999. 

Ardizzone, S., Bassi, G., and Liborio, G., Preparation of cristalline zirconia powders. Characterization of the bulk phase and interfacial behaviour. Colloids Surf., 51, 207, 1990. 

Here we report on an adsorption and surface rheology study with /i-lacto-globulin (jS-LG) and /J-casein (jS-CS) at the water/air interface using essentially a newly designed profile analysis tensiometer that allows us to investigate adsorption processes at the surface of drops as well as bubbles. The differences in the interfacial behaviour of the two proteins is discussed. 

Summarising, clear phenomenological similarities were observed between bulk and interfacial gelling behaviour with changes in the molecular structure of glycinin. Besides, foaming properties could be related to interfacial behaviour of glycinin in relation to aspects of the molecular structure. 

For constant dilation rate Q Joos van Uffelen discussed the dynamic interfacial behaviour (1993a, b). They compared the theory of Loglio, summarised by Miller et al. (1991), with the one presented by van Voorst Vader et al. (1964). For interfaces with constant dilation rate the relation... 

Many food items contain emulsions and foams, which are often stabilised by proteins forming a protective membrane at the interface. By preparing the food, adsorption of the available proteins, - by virtue of their surface activity -, is performed at the liquid/air (foams) and/or at the liquid/liquid (emulsions) interface. One way to study the interfacial behaviour of food proteins at those interfaces is to follow the interfacial tension decay accomplished by the adsorption of the proteins. 

What does the different r-Cp-dependence of the proteins, as is obvious in Figure 5, tell us about their interfacial behaviour Firstly, we compare the two extremes, i.e. the interfacial behaviour of the caseinate (0.2-7) and the soy protein (0-7). 

Today a rather detailed knowledge of the conformational changes of nucleic acids and proteins in the solution state is available with NSRS and this knowledge is continuously growing On the other hand much less information exists about the interfacial behaviour of these biopolymers, due to the lack of suitable methods. However, the following important processes are typically interfacial ... 

Metal colloids in an aqueous solution are ideal markers for cell surfaces and intracellular components for microscopic observation (light and fluorescence microscopy, transmission and scanning electron microscopy) and for studying molecular organization and cell function It also has numerous medical uses as a drug and as a test for various diseases For more specific information about the interfacial behaviour... 

In order to see how these results of the short-range enhancement (cf. Chapt. 4.1) can be used to study the interfacial behaviour of the enzyme lysozyme, the SERS spectrum of this protein in the adsorbed state at a charged silver surface is shown in Fig. 24. The spectrum observed at 0.6 V vs. SCE exhibited very high signal-to-noise ratios for a solution concentration as low as 0.2 mg/ml. This concentration is about two hundred times smaller than in the NSRS spectroscopy... 

In terms of thermodynamics, Torza and Mason [32] pioneered the study of the interfacial behaviour of systems containing various types of three mutually immiscible liquids. In their case, the thermodynamics of the system was influential in determining the final morphology since the liquid phase was highly mobile. The equilibrium state of the three phases will occur when the minimum free energy, Gs, defined below, is attained ... 

Z Yan. Interfacial behaviour of de-asphalted bitumen. MSc dissertation. University of Alberta, Edmonton, 1997. 

Trasatti S (1987) Interfacial behaviour of non-aqueous solvents. Electrochim Acta 32 843-850 Trasatti S (1995) Surface science and electrochemistry concepts and problems. Surf Sci 335 1-9 Verdaguer A, Sacha GM, Bluhm H, Salmeron M (2006) Molecular structure of water at interfaces wetting at the nanometer scale. Chem Rev 106 1478-1510 Vogler EA (1999) Water and the acute biological response to surfaces. J Biomater Sci Polymer Edn 10 1015-1045... 

Figure 20.32. The interfacial behaviour of polymer-surfactant mixtures depends on several factors such as the bulk properties of complexes formed, the surfactant association to free and interfacial polymer chains and the affinity of the polymer and the surfactant for the interface. (By courtesy of Fredrik Joabsson)...

The interfacial behaviour of surfactant-polymer mixtures, utilized for example in the stabilization of suspensions, depends on a complex interplay between different pair interactions. Addition of a polymer can either remove surfactant from a surface or enhance its adsorption, and vice versa, depending on the relative stability of the polymer-surfactant complexes in solution and at the interface. 

Therefore, for the optimisation of the design of hquid-liquid contacting equipment and the improvement of mass transfer processes the interfacial hydrodynamics needs to be well understood, so that it can be taken into account at a design stage and if necessary (and possible ), enable the manipulation of the interfacial behaviour to enhance the mass transfer rates. 

In the next sections experimental results obtained with the Schlieren and Mach Zehnder methods are presented. It becomes apparent that the SchUeren visuahsation of interfaces is an excellent method to give a clear idea of the interfacial behaviour during mass transfer, from which one can infer its effect on mass transfer. 

Therefore the addition of a surfactant to a liquid-liquid system may either promote Marangoni convection or dampen interfacial motions, depending on the type of liquid-liquid system and surfactant. Stability criteria have been established for many years for ternary and binary systems and when the solute has surface-active properties, but they are still a long way from being able to predict the interfacial behaviour accurately. Plots of the variation of equilibrium interfacial tension with surfactant concentration may be used to give a good indication of the interfacial behaviour during mass transfer. 

The author and co-workers have recently started work on the effect of the dynamic interfacial tension on the interfacial behaviour in systems undergoing mass transfer and this may bring more light to the topic presented here. 

In conclusion, more research needs to be carried out to understand the effect of surfactants on interfacial behaviour, which leads to increases in mass transfer rates - to be able to specify a surfactant that will enhance mass transfer in a particular process is an appealing prospect. 

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