Ross foam

S. Ross, Foams Encyclopedia of Chemical Technology, 3rd ed., Vol. 2, Wiley, New York, 1980. 

Another type of foam has been observed when a multicomponent liquid has a composition close to a separation into two liquid phases. Surface tension drops to a very low value, allowing easy formation of bubbles. An example is found in solvent recovery from lubricating-oil extraction processes. This type of foam has been referred to as Ross foam,f ° named after an investigator of these foams. 

Ross Foam Foam produced from a binary or ternary solution under conditions in which its temperature and composition approach (but do not reach) the point of phase separation into separate immiscible liquid phases. 

S. J. Ross, The Inhibition of Foaming, Bulletin No. 63, Rensselaer Polytechnic Institute, Troy, N.Y., 1950. 

Ross, S. Mechanisms of Foam Stabilization and Antifoaming Action, Chem. Eng. Progr. 63, 9, (1967) p. 41. 

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. 

Maurer et al. [57] determined the foaming power of octadecyl sulfuric acid and several of its salts, such as sodium, triethylamine, triethanolamine, and some amino acids. Foam capacity, measured by the Ross-Miles test [150] at 60°C, was in the range of 180-210 mm showing comparatively few differences. 

Chlebicki and Slipko [127] determined the foam ability of sodium propoxyl-ated alcohol sulfates by the Ross-Miles method. These substances are low-foaming surfactants the greatest foam height was observed for dodecyl and tetradecyl chains. As expected, as the number of polyoxypropylene units on the same alcohol chain increases, foam height decreases. The maximum foam height obtained was 225 mm for a 2 g/L solution of sodium tetradecyl (1 PrO) sulfate. 

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

FIG. 4 Influence of the alkyl chain on the foam of some alkyl ether carboxylates. Foam height according to Ross and Miles. 0.1% A.M. in 1% NaOH solution, EO = 3 t = 20°C, 15°gh. (From Refs. 61 and 64.)... 

Gafa and Lattanzi [6] determined the foaming power of commercial surfactants including AOS, LAS, AS, and SAS in 1 g/L solutions at 40°C according to a modified Ross-Miles method [66]. Their data, shown in Table 24, show that the best foaming products are the AOS and AS compounds followed by LAS and SAS. 

TABLE 24 Foaming Power of AOS and Reference Surfactants According to a Modified Ross-Miles Test at 40°C and 1 g/L Surfactant Concentration... 

Ross-Miles foam test (ASTM D1173-53) 160/150 mm 155/145 mm... 

Foaming plays an important part for many applications. Figure 8 shows foaming behavior of sulfosuccinates expressed as foam height in the Ross-Miles test. 

FIG. 8 Foaming behavior of sulfosuccinates—Ross-Miles method. 

A great number of nonionic surfactants have been ethoxylated and subsequently reacted with P4O10. The acid phosphate esters from this reaction possess surface properties and detergency similar to the nonionic surface-active agents employed as reactants. Detergency tests and foam heights from the Ross-Miles method have been reported for a series of compounds. Various formulations for all-purpose cleaners are given as well [37,40,41,44,48]. 

Ross and Miles foam heights with amide fatty acid amides, 2 456t viscosify enhancement, 2 455t Sodium C14-16 olefin sulfonate cosmetic surfactant, 7 834t... 

Test Methods. Surface tension (y) measurements were taken by Wil-helmy method (25+0.1°C). Critical micelle concentrations (cmc) were obtained from Y logC curves. Contact angle. Type GI, Japan. Wetting test. Canvas disk method, CIS,HG-2-380-66. Foam test, Ross-Miles lather method. Emulslbillty was determined by mixing 20 ml of 2.5%... 

Support for this postulation came from work done on the shape of the ideal foam cell [32-40]. Ross and co-worker [34,35] proposed three minimal geometric structures, i.e. those which will subdivide space with minimum parti-tional area. These were the pentagonal dodecahedron, the minimal tet-rakaidecahedron, originally suggested by Thomson (Lord Kelvin), and the P-tetrakaidecahedron (Fig. 4). 

B.E. Zehner and S.R. Ross, ABS foam and method of making same, US Patent 6 784 216, assigned to Crane Plastics Company LLC (Columbus, OH), August 31,2004. 

Morrison. I.D.. and S. Ross Colloidal Dispersants Suspensions, b.mulsions amt Foams. John Wiley Sons, Ine. New- York. NY 2002 Scheuing, D.R.. Ed. Ftturier Transform Infrared Spectroscopy in Colloid and Interface Science, American Chemical Society. Washington, DC, 199t... 

To the extent that viscosity and surface viscosity influence foam stability, one would predict that stability would vary according to the effect of temperature on the viscosity. Thus some petroleum industry processes exhibit serious foaming problems at low process temperatures, which disappear at higher temperatures. Ross and Morrison [25] cite some examples of petroleum foams that become markedly less stable above a narrow temperature range that may be an interfacial analogue of a melting point. 

Figure 32. Foam properties of propylene oxide adduct of secondary alcohol ethoxylate compared with those of others. Test conditions method—Ross-Miles (JIS-K-3362) surfactant concentration—1.0 wt % water temperature—25°C. ((- -) Cn.H SAE (7EO) + (4.5PO) (-1-) CI2 + Ii PAE (7EO) + (4.5PO) (-U-) HPE (8EO) + (4.5PO))...

Refs. [i] Evans ED, Wennerstrom H (1999) The colloidal domain. Wiley-VCH, New York, pp 217 [ii] Hunter RJ (2004) Foundations of colloid science, 2nd edn. Oxford University Press, Oxford, pp 539 [iii] Hamaker HC (1937) Physics 4 1058 Morrison ID, Ross S (2002) Colloidal dispersions. Suspensions, emulsions, and foams. Wiley Interscience, New York, pp 355... 

The antiatherosclerotic effect of proanthocyanidin-rich grape seed extracts was examined in cholesterol-fed rabbits. The proanthocyanidin-rich extracts [0.1% and 1% in diets (w/w)] did not change the serum lipid profile, but reduced the level of the cholesteryl ester hydroperoxides (ChE-OOH) induced by 2,2/-azo-bis(2-amidinopropane-dihydrochloride (AAPH), the aortic malonaldehyde (MDA) content and severe atherosclerosis. The immuno-histochemical analysis revealed a decrease in the number of the oxidized LDL-positive macrophage-derived foam cells on the atherosclerotic lesions of the aorta in the rabbits fed the proanthocyanidin-rich extract. When the proanthocyanidin-rich extract was administered orally to the rats, proantho-cyanidin was detected in the plasma. In an in vitro experiment using human plasma, the addition of the proanthocyanidin-rich extract to the plasma inhibited the oxidation of cholesteryl linoleate in the LDL, but not in the LDL isolated after the plasma and the extract were incubated in advance. From these results, proanthocyanidins of the major polyphenols in red wine might trap ROSs in the plasma and interstitial fluid of the arterial wall, and consequently display antiatherosclerotic activity by inhibiting the oxidation of the LDL [92]. 

The quantity xp is a much better defined characteristic of foam stability (since the pressure in the borders along the height of the foam column remains constant during its destruction). This parameter is also much more sensitive to the kind of surfactant, electrolyte concentration and other additives, compared to the lifetime of the foam in gravitational field, with an averaged pressure value from 0 to pgH. Estimation of the stability of foams from different surfactants by xp and by the Ross-Miles test has been reported in [16]. The results are discusses in Section 7.6.1. The advantages of the Foam Pressure Drop Technique and, respectively, xp as a characteristic of the foam stability, are clearly shown. 

The effect of the foam film type has been discussed in Section 7.5.1. However, a question arises as to whether the Ross-Miles method can be employed in testing foams built up by the three types of foam films. The answer is given by the data presented in Fig. 7.12. 

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