Rheology surfactants

The next section discusses chemical structures, synthesis, and purification of gemini surfactants. Section III reviews the behavior of gemini surfactants in solutions below the CMC. Section IV deals with their behavior at interfaces. The fifth section reviews micelle formation and solubilization. Section VI deals with micelle properties. Microstructure of aqueous solution of gemini surfactants, rheology of these solutions, and mixed micellization are considered in the following three sections. Section X deals with the phase behavior of... 

In modem industrial practice, compositions often contain pigments, reinforcements, rheological modifiers, surfactants, and other materials in addition to fillers. These materials can function synergisticaHy in the system. Hence, more complex models are needed to predict the optimal filler loading. ExceUent discussions of filler loading and selection in plastics are given (9,10). 

Based on the underlying physical chemistry of surfactants at interfaces, important features of foam stmcture, stabiHty, rheology, and their interrelationships can be considered as ultimately originating in the molecular composition of the base Hquid. 

Many different combinations of surfactant and protective coUoid are used in emulsion polymerizations of vinyl acetate as stabilizers. The properties of the emulsion and the polymeric film depend to a large extent on the identity and quantity of the stabilizers. The choice of stabilizer affects the mean and distribution of particle size which affects the rheology and film formation. The stabilizer system also impacts the stabiUty of the emulsion to mechanical shear, temperature change, and compounding. Characteristics of the coalesced resin affected by the stabilizer include tack, smoothness, opacity, water resistance, and film strength (41,42). 

Because of this interaction, PVP has found appHcation in surfactant formulations, where it functions as a steric stabilizer for example to generate uniform particle-size polystyrene emulsions (110—112). In a variety of formulations, a surfactant s abiHty to emulsify is augmented by PVP s abiHty to stabilize coUoids stericaHy and to control rheology. 

The concepts of interface rheology are derived from the rheology of three-dimensional phases. Characteristic for the interface rheology is the coupling of the motions of an interface with the flow processes in the bulk close to the interface. Thus, in interface rheology the shear and dilatational stresses of the interface are in equilibrium with the corresponding shear stress in the bulk. An important feature is the compressibility of the adsorption layer of an interface in contrast, the flow elements of the bulk are incompressible. As a result, compression or dilatation of the adsorption layer of a soluble surfactant is associated with desorption and adsorption processes by which the interface tends to reinstate the adsorption equilibrium with the bulk phase. 

Ether carboxylates are used not only in powdered detergents but in liquid laundry detergents for their hard water stability, lime soap dispersibility, and electrolyte stability they improve the suspension stability and rheology of the electrolyte builder [130,131]. Formulations based particularly on lauryl ether carboxylate + 4.5 EO combined with fatty acid salt and other anionic surfactants are described [132], sometimes in combination with quaternary compounds as softeners [133,163]. Ether carboxylates show improved cleaning properties as suds-controlling agents in formulations with ethoxylated alkylphenol or fatty alcohol, alkyl phosphate esters or alkoxylate phosphate esters, and water-soluble builders [134]. 

The effects of different surfactants on the rheological behavior of cement-water dispersions were studied by a rotational-type viscometer. The type of... 

Lu B, Zheng Y, Scriven LE, Davis HT, Talmon Y, Zakin JL (1998) Effect of variation counterion-to-surfactant ratio on rheology and micro-structures of drag reducing cationic surfactant systems. Rheol Acta 37 528-548... 

Molecularly motivated empiricisms, such as the solubility parameter concept, have been valuable in dealing with mixtures of weakly interacting small molecules where surface forces are small. However, they are completely inadequate for mixtures that involve macromolecules, associating entities like surfactants, and rod-like or plate-like species that can form ordered phases. New theories and models are needed to describe and understand these systems. This is an active research area where advances could lead to better understanding of the dynamics of polymers and colloids in solution, the rheological and mechanical properties of these solutions, and, more generally, the fluid mechaiucs of non-Newtonian liquids. 

To solve this problem, modern pesticide formulations use a variety of additives (adjuvants) to improve the mass efficiency. Surfactants and polymeric rheology modifiers are used to reduce spray drift, surfactants are used to modify surface tension and reduce... 

Weatherley (1998) has discussed all the relevant aspects of the separation of low molecular weight biologically produced molecules by solvent extraction. A high degree of selectivity can be realized by careful selection of the solvent. Problems associated with the rheology of the broth, the presence of surfactants and solid materials needs to be recognized. There is a scope to consider intensified electrostatic contact for broth dispersion and separation. Examples covered in this treatise include penicillin G and cA-dihydrodiols. 

Alkylpolyglucosides (APGs) are highly biodegradable surfactants [1344]. The addition of APGs, even at very low concentrations, to a polymer mud can drastically reduce the fluid loss even at high temperatures. Moreover, both fluid rheology and temperature resistance are improved. 

Interfacial rheologic properties of different crude oil-water systems were determined in wide temperature and shear rate ranges and in the presence of inorganic electrolytes, surfactants, alkaline materials, and polymers [1056]. 

T. R. French and C. B. Josephson. The effect of polymer-surfactant interaction on the rheological properties of surfactant-enhanced alkaline flooding formulations Topical report. US DOE Fossil Energy Rep NIPER-635, NIPER, February 1993. 

GP Martin, C Marriott, I Kellaway. (1976). The effect of natural surfactants on the rheological properties of mucus. J Pharm Pharmacol 28 76P. 

Oil-field chemistry has undergone major changes since the publication of earlier books on this subject Enhanced oil recovery research has shifted from processes in which surfactants and polymers are the primary promoters of increased oil production to processes in which surfactants are additives to improve the incremental oil recovery provided by steam and miscible gas injection fluids. Improved and more cost-effective cross-linked polymer systems have resulted from a better understanding of chemical cross-links in polysaccharides and of the rheological behavior of cross-linked fluids. The thrust of completion and hydraulic fracturing chemical research has shifted somewhat from systems designed for ever deeper, hotter formations to chemicals, particularly polymers, that exhibit improved cost effectiveness at more moderate reservoir conditions. 

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