Foaming properties

For gear trains Protection from seizing and rapid wear Extreme-pressure and anti-wear properties Resistance to oxidation Thermal stability High viscosity Low pour point Anti-foaming properties Anti-corrosion properties... 

A.gllsethionates. These are among the oldest of the synthetic detergents and were developed ia Germany to overcome problems of hard water. They are prepared by reaction of fatty acid chlorides with a salt of isethionic acid, ie, 2-hydroxyethanesulfonic acid [107-36-8]. These detergents have moderate foaming properties and have seen only limited use ia shampoos. 

Many of the surfactants made from ethyleneamines contain the imidazoline stmcture or are prepared through an imidazoline intermediate. Various 2-alkyl-imidazolines and their salts prepared mainly from EDA or monoethoxylated EDA are reported to have good foaming properties (292—295). Ethyleneamine-based imida zolines are also important intermediates for surfactants used in shampoos by virtue of their mildness and good foaming characteristics. 2- Alkyl imidazolines made from DETA or monoethoxylated EDA and fatty acids or their methyl esters are the principal commercial intermediates (296—298). They are converted into shampoo surfactants commonly by reaction with one or two moles of sodium chloroacetate to yield amphoteric surfactants (299—301). The ease with which the imidazoline intermediates are hydrolyzed leads to arnidoamine-type stmctures when these derivatives are prepared under aqueous alkaline conditions. However, reaction of the imidazoline under anhydrous conditions with acryflc acid [79-10-7] to make salt-free, amphoteric products, leaves the imidazoline stmcture essentially intact. Certain polyamine derivatives also function as water-in-oil or od-in-water emulsifiers. These include the products of a reaction between DETA, TETA, or TEPA and fatty acids (302) or oxidized hydrocarbon wax (303). The amidoamine made from lauric acid [143-07-7] and DETA mono- and bis(2-ethylhexyl) phosphate is a very effective water-in-od emulsifier (304). 

The properties of a foam are determined by the properties of the polymer, and by the relative density, p/p - the density of the foam (p) divided by that of the solid (p ) of which it is made. This plays the role of the volume fraction Vf of fibres in a composite, and all the equations for foam properties contain p/p. It can vary widely, from 0.5 for a dense foam to 0.005 for a particularly light one. 

Glasl [149] reported the foaming properties of several alcohol sulfates and alcohol ether sulfates using the perforated disk method as described in the DIN standard 53902. All values were obtained at 0.28 g/L surfactant concentration, both in distilled water and in water of 16°dH hardness at 20, 40, and 60°C. The results are shown in Figs. 15-17. 

The foaming properties of sodium symmetrical secondary alcohol sulfates, sodium secondary alcohol sulfates, isomeric sodium secondary pentanol sulfates, and sodium linear alcohol sulfates were studied by Dreger et al. [72] via the Ross-Miles test [150] at 46°C. Within the linear series sodium tetradecyl sulfate produces the largest amount of foam. The influence of several electrolytes was also studied. 

Sodium alcohol sulfates have a limited solubility compared to sodium alcohol ether sulfates and are more suitable for cream, pearlized, and paste shampoos. Alcohol sulfates are more frequently used in general shampoo formulations in the United States than in Europe. Europe has moved toward alcohol ether sulfates for historical and traditional reasons, different availability of ethylene oxide, and possibly other technical reasons such as the more favorable dermatological properties of alcohol ether sulfates and their better behavior in hard waters. Triethanolamine alcohol sulfates are widely used in shampoos because of their comparatively high solubility in water, good foaming properties, and low irritancy. 

Alcohol ether sulfates are used in mixture with sulfonates, either alkyl-benzenesulfonates or a-olefinsulfonates, and other surfactants, such as fatty alkanolamides, in manual liquid dishwashing detergents and light-duty detergents. These combinations show the excellent emulsifying and foaming properties required in dishwashing. 

The well-known traditional detergent basic material soap often causes problems because of its sensitivity to water hardness, i.e., poor lime dispersibility we encounter stability problems, reduced detergent power, and inferior foaming properties in hard water. 

With ether carboxylates the above-mentioned problems do not arise due to the polyglycol ether group in the molecule. Therefore ether carboxylates show good hard water stability as well as good detergent and foam properties in hard water. It is even possible to disperse lime soaps [61,62,64]. However, the ether carboxylates have the same creamy foaming properties as soap. 

The foam properties of ether carboxylates are dependent on the fatty chain and ethoxylation degree. High foaming effect can be achieved with a longer fatty chain, with an optimal effect using C12-C14 chain, and a relatively short EO degree, with an optimum at about 4.5 EO [10,51,57] (Table 8). 

TABLE 8 Foam Properties of Some Alkyl Ether Carboxylates According to Ross and Miles... 

These higher foaming properties are very useful for such cosmetic formulations as shampoos, showerbaths, and so on. This is the same with the forming of fine bubbles and the improving of foam stability of other surfactants such as, for example, alkyl ether sulfates due to the combination with ether carboxylates [57,67-69] (Table 9). 

Due to the good lime soap dispersing properties it is possible to improve the foaming properties of hard water-susceptible surfactants. Improvement of the formulation of a fatty acid soap by laureth-17 carboxylic acid, sodium salt [57,62], and an amidether carboxylate [62] has been described. 

FIG. 6 Influence of the temperature on the foaming properties of an alkyl ether carboxylate compared to an alcohol ethoxylate. 0.1% solution, pH = 11. (From Refs. 61 and 64.)... 

The influence of fatty chain and ethoxylation degree on mildness and foaming properties is very important [57,78]. A longer fatty chain and a higher ethoxylation improves the mildness however, a small decrease in foam has been found. 

In combination with alkyl ether sulfates, a synergistic decrease of the irritation level of the ether sulfates and an improvement of the foam stabilization has been described [57,67,78]. A good compromise between mildness and foam properties could be achieved with lauryl ether carboxylic acid sodium salt with 10 mol EO [57,67]. In several articles examples of the use of alkyl ether carboxylates as cosurfactant in mild shampoos as well as bath and shower products have been described [57,69,79]. 

For use in soap bars, a smooth feel after washing, mildness, lime soap dispersing effect, and foaming properties are important [36,104-106]. In transparent soap bars the clarity will be improved [104], in half-syndet soaps mildness and foam are increasing [105,106] combined with a smooth feel after use [105], With lauryldiglycolamidether carboxylate a good foaming and mild syndet soap has been formulated [36]. 

In 1991 the use of amidether carboxylate in combination with anionics like alkanesulfonate, alkylbenzolsulfonate, and alkyl ether sulfate to improve mildness and foam properties in the presence of soil was described [72]. Later a comparison study of the use of alkyl ether carboxylate, amidether carboxylate, and cocamidopropylbetaine in concentrated dishwashing formulations showed, in addition to the above-mentioned properties, the advantage of ether carboxylates in the construction of highly active formulations [144]. 

Muller et al. [80] described the use of IOS surfactants together with the sulfonate of a C12-C24 unsaturated fatty acid containing one to six double bonds in shampoo formulations they combine good detergency with good foam properties and mildness to the skin. 

When a-sulfo fatty acid esters are used as the major active component in detergents they can cause problems because of their foaming properties. In European horizontal drum-type automatic washers they produce too much foam, and in the rinse cycle of the American and Japanese pulsator-type washers the foam cannot be completely rinsed out [38]. The problem of inefficient rinsing can be solved by the addition of soap [63] or sulfonated unsaturated fatty acid esters [64]. For European applications special foam inhibitors are needed. 

The responses chosen all relate to important foam properties. We believed that yi, the emulsion droplet size, determines y2, the cell size in the resultant foam, and we wished to determine whether this is true over this range of formulations. The foam pore size ys should determine the wetting rate y7, so these responses could be correlated, and yg, the BET surface area, should be related to these as well. The density y and density uniformity ys are critical to target performance as described above, and ys, the compressive modulus, is an important measure of the mechanical properties of the foam. 

While drilling low-pressure reservoirs with nonconventional methods, it is conunon to use low-density dispersed systems, such as foam, to achieve underbalanced conditions. To choose an adequate foam formulation, not only the reservoir characteristics but also the foam properties need to be taken into account. Parameters such as stability of foam and interactions between rock-fluid and drilling fluid-formation fluid are among the properties to evaluate while designing the drilling fluid [13]. 

Based on prior knowledge of crude oil foaming properties, a separator large enough to cope with foam formation may be installed. 

The basis for the foam properties is given by interfacial parameters. Although correlations have been shown between a single parameter and foam properties, there is still a lack in a general correlation between interfacial properties and the foam behavior of complex systems in detergency. The simplest approach to correlate interfacial parameters to foam properties is the comparison of the surface activity measured by the surface tension of a surfactant system and foam stability. 

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