Surfactant solutions classification

It is understood that manufacturing of liquid detergents that are unstructured in their commercial form may involve intermediate streams which are, in fact, structured fluids, such as surfactant solutions at high active concentrations, within anisotropic mesophase boundaries, or concentrated polymeric solutions and gels. Whether the source is raw material, premix, or final product, manufacturing operations for each of these classifications are discussed with a focus on any specific requirements or limitations due to the physicochemical form. 

The rheological properties show particularly large changes and in many cases the solutions show a non-Newtonian behavior and for a number of cases pronounced viscoelasticity has been demonstrated. That the classification of a certain surfactant depends very much on temperature is probably best illustrated by the viscosity of... 

Surfactant additives have been studied intensively in recent years because of the self-reparability or self-assembly of their micro structures after degradation by mechanical or extensional stresses. This ability has led to many studies of their applications in DHC recirculation systems. Classifications of surfactant DR As and their self-assembly nature are described. Also discussed in this section are the main research results on microstructures, rheological properties, HTR of surfactant DR solutions, and approaches to enhance heat transfer coefficients. Significant field tests around the world are reviewed. 

The first section of this chapter describes the solution properties of polymers, and this is followed by a general classification of polymeric surfactants. Examples are provided of polymeric surfactants and polyelectrolytes that are used as dispersants and emulsifiers. 

This commentary on the current status of research on heats of immersion begins where our review written in 1958 concludes [6]. The classification of heats of immersion of solids into liquids as a function of precoverage is expanded to include two new types of curves. Several difficulties in heat of immersion research are discussed. Then, current applications of heats of immersion to determine the average polarity of solid surfaces, heterogeneities on solid surfaces, wetting by surfactants, hydrophilicity of solid surfaces, and thermodynamics of the specific interaction of molecules from solution onto solid surfaces are described. 

Yang, S. and Khaledi, M.G, Chemical selectivity in micellar electrokinetic chromatography characterization of solute-miceUe interactions for classification of surfactants. Anal. Chem., 61, 499, 1995. 

It will be noted that HLB numbers are most often used in connection with nonionic surfactants. While ionic surfactants have been included in the HLB system, the more complex nature of the solution properties of the ionic materials makes them less suitable for the normal approaches to HLB classification. In cases where an electrical charge is desirable for reasons of stabihty, it is often found that surfactants that have limited water solubiUty and whose hydrophobic structure is such as to inhibit efficient packing into micellar structures should be most effective emulsifiers. Surfactants such as the sodium trialkylnaphthalene sulfonates and dialkylsulfo-succinates, which do not readily form large micelles in aqueous solution, have found some use in that context, usually providing advantages in droplet size and stabihty over simpler materials such as sodium dodecyl sulfate. 

The cmc is indicated by an arrow. The three nonpolar phases, SAS, MOS and ODS Hypersil , show a Langmuir-like adsorption isotherm with a concave shape or L type in the Giles classification [12]. The polar CPS phase shows a convex shape or S type cooperative adsorption. The amount of adsorbed surfactant increases in the order bare silica < CPS < SAS < MOS < ODS. This is exactly the decreasing order of the stationary phase polarity. No adsorption of SDS on the bare silica was observed in this low concentration range [11]. Above 0.004 M, the SDS adsorption on SAS Hypersil passes the one on MOS Hypersil . Hydrophobic interactions are mainly responsible for SDS adsorption in sub micellar solutions. 

The classification is done by adding 1 ml of the mixed indicator (disulphine blue V and dimidium bromide) to two small portions of a solution of the surfactant, one acid and the other alkaline, adding a few... 

Some classification of parameters in their connection with physical or mechanical processes is to be done. The main parameter connecting hydrodynamic and diffusion parts of the film flow problem with surfactant is Marangoni number Ma. The both variants of positive (Ma > 0) and negative (Ma < 0) solutal systems are considered. The main hydrodynamic parameters are Re, 7 or equivalently S. 7. This two values determine the mean film thickness i/, mean velocity and flow rate as well as parameter k. The diffusion parameters Pe,co determine the local thickness of diffusion boundary layer h and smallness parameter e. Two values T, Di characterize the masstransfer of surfactant by the adsorption-desorption and the intensity of dissipation by the surface diffusion. Besides the limiting case of fast desorption (T = 0) the more general case (T 1) are considered. Intensity of the surfactant evaporation by parameter Bi is determined. The remaining parameter G gives an indication to the typical value of surface excess concentration A in comparison with c. ... 

This chapter will start with a short account of the general classification and description of polymeric surfactants. This is followed by a summary on then-solutions properties. The adsorption and conformation of polymeric surfactants at the solid-liquid interface will be discussed at a fundamental level and some experimental results will be presented to illustrate the prediction of the theories. The interaction energies between particles or droplets containing adsorbed polymeric surfactants will be briefly described. The final section will give some applications of polymeric surfactants in suspensions, emulsions, and multiple emulsions. 

The aggregation of surfactants into clusters or micelles in dilute solutions, as we will see, is a direct consequence of the thermodynamic requirements of the particular surfactant-solvent system under consideration. It has been suggested that phases occurring between the simplest micelles and true crystals are natural consequences of the removal of water from the micellar system, but do not constitute thermodynamically distinct states. In other words, the factors determining the structures of the mesophases are identical to those that control the formation of micelles in the first place. The same would be true of aggregates other than micelles, which do not fall under the classification of mesophases. 

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