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Straight-chain surfactants, effect

Studies on non-ionic surfactants as effective drag-reducing additives have been submitted by Zakin (1972). He studied various effects on three non-ionic surfactants formed from straight-chain alcohols and ethyleneoxide. These surfactants have an upper and a lower temperature limit for solubility in water and prove effective drag reducers near their upper critical solubility temperature or clouding point. The clouding point is the point at which a solution of a non-ionic agent in water becomes turbid as the temperature is raised. [Pg.123]

Change in the length of the hydrophobic group of straight-chain ionic surfactants beyond 10 carbon atoms appears to have almost no effect on the effectiveness of adsorption at the aqueous solution-heptane interface and very little effect on the effectiveness at the aqueous solution-air interface. [Pg.81]

Depression of the CMC appears to be greater for straight-chain compounds than for branched ones and increases with chain length to a maximum when the length of the hydrophobic group of the additive approximates that of the surfactant. An explanation for these observations (Schick, 1957) is that those molecules that are most effective at reducing the CMC are solubilized in the outer portion of the micelle core and are there under lateral pressure tending to force them into the inner... [Pg.146]

The most effective additives for increasing the stability of the foam produced by surfactant solutions appear to be long-chain, often water-insoluble, polar compounds with straight-chain hydrocarbon groups of approximately the same length as the hydrophobic group of the surfactant. Examples are lauryl alcohol for use with sodium dodecyl sulfate, Af,/V-bis(hydroxyethyl) lauramide for use with dodecylbenzenesulfonate, lauric acid for use with potassium laurate, and N,N-dimethyldodecylamine oxide for use with dodecylbenzenesulfonate and other anionics. [Pg.295]

The following data for the cmc and aggregation number, N, were obtained for a typical straight-chain anionic hydrocarbon surfactant in solutions of various salt concentrations. Assuming a spherical geometry, calculate for each system the volume of the hydrocarbon core, the effective radius of the core, and the cross-sectional area per chain at the aggregate surface. [Pg.395]

As the preceding example indicates, micelle formation can be promoted by increasing the length of the surfactant s (straight) hydrocarbon chain or by reducing the repulsion between the head groups. As an illustration of the chain length effect, the measured CMC of sodium alkyl sulfates at 40°C decreases from 140 mM for the Cg compound to 8.6 mM for the C,2 compound to 0.58 mM for the... [Pg.180]

In the formation of microemulsions, both ionic and nonionic surfactants are used. Cosurfactants are alcohols or amines [1,5,6,13,14]. It has been shown [23] that straight chain amines are quite different from their corresponding alkanols as cosurfactant. For example, butylanfine is a more effective one on mass basis than triethylene glycol monobutyl ether. It is because the primary amine head group is more hydrophilic than alcohol, nitrile, carboxylic add, ketone, and aldehyde head groups. In the case of amine cosurfactants, the addition of acid makes the cosurfactant more hydrophilic whereas the addition of base makes it less hydrophilic. The relative degree of hydrophilidty at the oil/water interface determines the volume of microemulsion formation. Microanulsions represent complex phase behavior, and the chemical structure of the cosurfactant has a pivotal role to play on their phase behaviors. [Pg.21]

This is not the end of the story, however. A third type of effect can alter the selfassociation structure and is directly related to the surfactant and or alcohol inherent properties. For instance, straight-chain ionic surfactants would produce liquid crystals of the lamellar type unless the temperature is quite elevated. Thus, in most cases of ionic systems, a large amount of alcohol (as much as two or three times the surfactant amount on a mole fraction basis) is required to melt the liquid crystal into a microemulsion, particularly for middle-phase ones [33]. Note, however, that too much alcohol could be detrimental to a high-performance microemulsion because the alcohol molecules which are not playing a cosurfactant role at the interface would dissolve into the bulk of one or both excess phases, making them more compatible [i.e., the alcohol would make the water less polar and the oil more polar (depending on the alcohol, but most particularly, intermediate solubility ones such as secondary butanol or tertiary pentanol)]. This is, of course, a way to narrow the miscibility gap, but this time by favoring the formation of a cosolubilized random mixture of all molecules instead of a microemulsion structure [50,65]. [Pg.272]


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Chain effect

Effective chain

Straight

Straight chain

Straightness

Surfactant chain

Surfactant effectiveness

Surfactants, effects

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