Dynamic surface behaviour

Luckham P F and Manimaaran S 1997 Investigating adsorbed polymer layer behaviour using dynamic surface forces apparatuses—a review Adv. Coiioid interface Sc/. 73 1 -46... 

Prins, A., van Kalsbeek, H.K.A.I. (1998). Foaming behaviour and dynamic surface properties of liquids. Current Opinion in Colloid and Interface Science, 3, 639-642. 

Many surfactant solutions show dynamic surface tension behaviour. That is, some time is required to establish the equilibrium surface tension. If the surface area ofthe solution is suddenly increased or decreased (locally), the adsorbed surfac-... 

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. 

Laboratory tests may provide additional quantitative information on different physico-chemical properties, useful to predict the environmental behaviour of the complex mixture of natural and man-made organic compounds encountered in marine waters. In particular, in previous articles we dealt with laboratory measurements of static and dynamic surface tension of sea water samples (Loglio et al. 1986, 1987, 1998a). 

In this book we are only concerned with the electrostatic repulsion aspect of the surface behaviour of charged surfactants, and then, as shown later, their electrostatic retardations effects. Such kinetic effects are in some cases decisive dynamic properties of a liquid interface and therefore significant for applications in colloid science and technology. 

The dynamic surface tensions of aqueous solutions of pt-BPh-EOlO at five concentrations are shown in Fig. 5.31, obtained from complementary bubble pressure and drop volume measurements. The curves show the typical course of y(log rj-behaviour for a diffusion... 

In some cases, a better agreement with the experimental surface tension isotherms and other data (dynamic surface tension, optical methods) is provided by the reorientation or aggregation model, respectively. It follows from the presented results that the reorientation model is more appropriate for oxyethylated surfactants and for surfactants which possess relatively high molar area, ro > 2.5-lO m /mol. At the same time, the aggregation and cluster models describe better the behaviour of surfactants with a relatively large Frumkin constant and low molar area, (o< 2.5-10 m /mol. 

A much more complex behaviour is observed for the process of penetration of various proteins into phospholipid monolayers. This behaviour depends strongly on the protein and the solution properties although some common features are observed. Fainerman et al. [116] studied the P-lactoglobulin penetration dynamics into DPPC monolayers. For a (i-lactoglobulin bulk concentration of 510 mol/l and molar areas of the lipid larger than the critical value, A > A, first order phase transitions are observed. Thus, two-dimensional condensed phase are formed although at these molar area values the pure DPPC monolayer exists only in the fluid-like state and does not form any domains. The first-order phase transition in the DPPC monolayer becomes visible by the characteristic break point in the dynamic surface pressure curve Fl(t) (see Fig. 4.50). 

New experimental methods created during the last two decades allow to investigate the concentration and frequency dependence of the dynamic surface elasticity more systematically. That is why the dynamic surface elasticity behaviour in the region of the CMC deserves special attention. Relations (5.264) in the first approximation take the form... 

The equilibrium and dynamics of adsorption processes from micellar surfactant solutions are considered in Chapter 5. Different approaches (quasichemical and pseudophase) used to describe the micelle formation in equilibrium conditions are analysed. From this analysis relations are derived for the description of the micelle characteristics and equilibrium surface and interfacial tension of micellar solutions. Large attention is paid to the complicated problem, the micellation in surfactant mixtures. It is shown that in the transcritical concentration region the behaviour of surface tension can be quite diverse. The adsorption process in micellar systems is accompanied by the dissolution or formation of micelles. Therefore the kinetics of micelle formation and dissociation is analysed in detail. The considered models assume a fast process of monomer exchange and a slow variation of the micelle size. Examples of experimental dynamic surface tension and interface elasticity studies of micellar solutions are presented. It is shown that from these results one can conclude about the kinetics of dissociation of micelles. The problems and goals of capillary wave spectroscopy of micellar solutions are extensively discussed. This method is very efficient in the analysis of micellar systems, because the characteristic micellisation frequency is quite close to the frequency of capillary waves. 

Many surfactant solutions show dynamic surface tension behaviour. That is, some time is required to establish the equilibrium surface tension. If the surface area of the solution is suddenly increased or decreased (locally), the adsorbed surfactant layer at the interface would then require some time to restore its equilibrium surface concentration by diffusion of surfactant from, or to the bulk liquid (see Reference [100] for a review). In the meantime, the original adsorbed surfactant layer itself is either expanded or contracted since surface tension gradients are now in effect, there arise Gibbs-Marangoni forces acting in opposition to the initial disturbance. 

Thermodynamics of Surfactant Adsorption Kinetics of Surfactant Adsorption Dynamic Surface Tension of Solutions Drop and Bubble Shape Experiments Adsorption Behaviour of Mixed Systems... 

The modulus at minimum and low strain amplitudes is due to the so-called filler network and it is accepted that the filler surface area, as well as the surface activity, play a major role in establishing a filler network, determining the effective contact area between filler particles and between filler particles and the elastomer matrix. The stress assisted disruption of the filler network causes the reduction of the modulus as the strain amplitude increases, giving rise to the non-linearity of the dynamic-mechanical behaviour of the rubber composite. This phenomenon is known as the Payne effect and it is (to a certain extent) reversible. The disruption and re-formation of the filler network is... 

This book presents coverage of the dynamics, preparation, application and physico-chemical properties of polymer solutions and colloids. It also covers the adsorption characteristics at and the adhesion properties of polymer surfaces. It is written by 23 contemporary experts within their field. Main headings include Structural ordering in polymer solutions Influence of surface Structure on polymer surface behaviour Advances in preparations and appUcations of polymeric microspheres Latex particle heterogeneity origins, detection, and consequences Electrokinetic behaviour of polymer colloids Interaction of polymer latices with other inorganic colloids Thermodynamic and kinetic aspects of bridging flocculation Metal complexation in polymer systems Adsorption of quaternary ammonium compounds art polymer surfaces Adsorption onto polytetrafluoroethylene from aqueous solutions Adsorption from polymer mixtures at the interface with solids Polymer adsorption at oxide surface Preparation of oxide-coated cellulose fibre The evaluation of acid-base properties of polymer surfaces by wettability measurements. Each chapter is well referenced. 

All three class types of surfactant studied exhibit a common behaviour in their dynamic surface tension properties in aqueous gelatin solution all show a maximum efficiency in DST reduction at a surface age of 0.1 s as their homologous series are ascended. 

Today, thanks to the fast development of computer enhanced imaging techniques and numerical fitting procedures, the accuracy and the sampling rate of drop shape methods are substantially increased. Thus, this technique is an important tool for the investigation of adsorption dynamics, and it is particularly suitable for studying processes with characteristic times from a few seconds up to hours and even longer. In fact, there is a large number of experimental studies in which the drop shape technique is used to evaluate the adsorption equilibrium properties, like adsorption isotherms and the dynamic surface tension behaviour. The method is also extensively utilised in the study of surfactants and proteins both in liquid/liquid and liquid/air systems. 

An example of such behaviour, studied by the drop shape method described here, is shown in Fig. 1 lb, where the dynamic surface tension during the adsorptive transfer of CioEOg at a fresh water/hexane interface is shown. The diffusion controlled approach can be applied to model the... 

The value of the critical micelle concentration (CMC) is an important parameter in a wide variety of industrial applications involving adsorption of surfactant molecules at interfaces, such as foams, froths, emulsions, suspensions, and surface coatings. It is probably the simplest means of characterizing the colloid and surface behaviour of a surfactant solute, which in turn determines its industrial usefulness. Many industrial processes are also dynamic processes in that they involve a rapid increase in interfacial area, such as foaming, wetting, emulsification and solubilization. First, the available monomers adsorb on to the freshly created interface. Then, additional monomers must be provided by the breakup of micelles. Especially when the free monomer concentration (i.e. CMC) is low, the micellar breakup time or diffusion of monomers to the newly created interface can be rate-limiting steps in the supply of monomers, which is the case for many nonionic surfactant solutions (3). 

Luckham, P. F. and Manimaaran, S., Investigating adsorbed polymer layer behaviour using dynamic surface force apparatuses - a review, Adv. Colloid Interface ScL, 73, 1 46 (1997). 

Prins, A., Dynamic surface properties and foaming behaviour of aqueous surfactant solutions, in Foams (Akers, R.J., ed.). Academic Press, London, 1977, p45. 

Abstract This chapter deals with the non-linear viscoelastic behaviour of rubber-rubber blend composites and nanocomposites with fillers of different particle size. The dynamic viscoelastic behaviour of the composites has been discussed with reference to the filler geometry, distribution, size and loading. The filler characteristics such as particle size, geometry, specific surface area and the surface structural features are found to be the key parameters influencing the Payne effect. Non-Unear decrease of storage modulus with increasing strain has been observed for the unfilled vulcanizates. The addition of spherical or near-spherical filler particles always increase the level of both the linear and the non-linear viscoelastic properties. However, the addition of high-aspect-ratio, fiber-like fillers increase the elasticity as well as the viscosity. 

L. Fiori, E. Ricci, E. Arato, P. Costa, Dynamic surface tension measurements on a molten metal-oxygen system the behaviour of the temperature coefficient of the surface tension of molten tin. J. Mater. Sci. 40(9-10), 2155-2159 (2005)... 

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