Wetting property

Lattice models have been studied in mean field approximation, by transfer matrix methods and Monte Carlo simulations. Much interest has focused on the occurrence of a microemulsion. Its location in the phase diagram between the oil-rich and the water-rich phases, its structure and its wetting properties have been explored [76]. Lattice models reproduce the reduction of the surface tension upon adsorption of the amphiphiles and the progression of phase equilibria upon increasmg the amphiphile concentration. Spatially periodic (lamellar) phases are also describable by lattice models. Flowever, the structure of the lattice can interfere with the properties of the periodic structures. 

By virtue of their simple stnicture, some properties of continuum models can be solved analytically in a mean field approxunation. The phase behaviour interfacial properties and the wetting properties have been explored. The effect of fluctuations is hrvestigated in Monte Carlo simulations as well as non-equilibrium phenomena (e.g., phase separation kinetics). Extensions of this one-order-parameter model are described in the review by Gompper and Schick [76]. A very interesting feature of tiiese models is that effective quantities of the interface—like the interfacial tension and the bending moduli—can be expressed as a fiinctional of the order parameter profiles across an interface [78]. These quantities can then be used as input for an even more coarse-grained description. 

Laibinis P E, Whitesides G M, Aiiara D L, Tao Y T, Parikh A N and Nuzzo R G 1991 Comparison of the struotures and wetting properties of seif-assembied monoiayers of normai-aikanethiois on the ooinage metai-surfaoes, Cu, Ag, Au J. Am. Chem. See. 113 7152-67... 

Atre S V, Liedberg B and Allara D L 1995 Chain length dependenoe of the struoture and wetting properties in binary oomposition monolayers of OH and CHj-terminated alkanethiolates on gold Langmuir 3882-93... 

Improved Hot—Wet Properties. Acryhc fibers tend to lose modulus under hot—wet conditions. Knits and woven fabrics tend to lose their bulk and shape in dyeing and, to a more limited extent, in washing and drying cycles as well as in high humidity weather. Moisture lowers the glass-transition temperature T of acrylonitrile copolymers and, therefore, crimp is lost when the yam is exposed to conditions requited for dyeing and laundering. 

Froth flotation (qv) is a significant use of foam for physical separations. It is used to separate the more precious minerals from the waste rock extracted from mines. This method reHes on the different wetting properties typical for the different extracts. Usually, the waste rock is preferentially wet by water, whereas the more valuable minerals are typically hydrophobic. Thus the mixture of the two powders are immersed in water containing foam promoters. Also added are modifiers which help ensure that the surface of the waste rock is hydrophilic. Upon formation of a foam by bubbling air and by agitation, the waste rock remains in the water while the minerals go to the surface of the bubbles, and are entrapped in the foam. The foam rises, bringing... 

Refs. 208 and 209 hot—wet properties and light stabiUty inferior to nylon-6 and nylon-6,6. Refs. 209 and 210 excessive property loss when wet. 

Cosmetics. Castor od and its derivatives are utilized in cosmetic and personal care products. The low pour point and high viscosity produce lubricity and wetting properties desired in Hpsticks. Basic Hpstick contains 20—44 wt % castor od, which also acts as an ideal dispersant for pigments (116). One Hpstick formula contains 38 wt % castor od and 9.5% glycerol monoricinoleate (117). 

Castor od fatty acid amide polyethylene ethers exhibited dispersant, antimicrobial, emulsifying, and wetting properties. Combining the ethers with... 

In porous and granular materials, Hquid movement occurs by capillarity and gravity, provided passages are continuous. Capillary flow depends on the hquid material s wetting property and surface tension. Capillarity appHes to Hquids that are not adsorbed on capillary walls, moisture content greater than fiber saturation in cellular materials, saturated Hquids in soluble materials, and all moisture in nonhygroscopic materials. 

Ethers, esters, amides and imidazolidines containing an epithio group are said to be effective in enhancing the antiwear and extreme pressure peiformance of lubricants. Other uses of thiiranes are as follows fuel gas odorant (2-methylthiirane), improvement of antistatic and wetting properties of fibers and films [poly(ethyleneglycol) ethers of 2-hydroxymethyl thiirane], inhibition of alkene metathesis (2-methylthiirane), stabilizers for poly(thiirane) (halogen adducts of thiiranes), enhancement of respiration of tobacco leaves (thiirane), tobacco additives to reduce nicotine and to reduce phenol levels in smoke [2-(methoxymethyl)thiirane], stabilizers for trichloroethylene and 1,1,1-trichloroethane (2-methylthiirane, 2-hydroxymethylthiirane) and stabilizers for organic compounds (0,0-dialkyldithiophosphate esters of 2-mercaptomethylthiirane). The product of the reaction of aniline with thiirane is reported to be useful in the flotation of zinc sulfide. 

Improve wetting properties. (See AVetting siihsection.) Increase hinder distrihiition. 

Pittman and Ludwig [115] studied the wetting properties of a series of flu-oroalkyl acrylates having -CH2(CF2) CF2H side chains, where n was 1, 3. 5, 7, or 9. The acrylates with n = 1 and 9 were partially crystalline (attributed to packing of the fluorochemical side chains) with melting points of about 56°C and... 

To produce a suitable rubber base adhesive, three key aspects are required (I) tack and wetting properties (2) adhesive strength (3) cohesive strength. 

Plasticizers/oils. These are added for several reasons (a) to improve the compatibility between SBR and the other additives (b) as extender (to reduce cost) (c) to soften the SBR (d) to change the wetting properties. The most common additives are organic phosphates, phthalate esters and aromatic hydrocarbon oils. 

As it can be seen in Fig. 1(c), there is a minimum size for the silver nitrate filling. If we assume that the polarisability of the enclosed material is identical to the bulk value, we can estimate the CNT cavity polarisability by using the measured minimal filled CNT. Then, if the cavity polarisability is size dependent, this approach can be used to measure the tube cavity properties, and we could also predict the wetting properties (or minimal filled tubes) for different materials. 

Coal tar epoxies These are a combination of epoxy resins and selected coal tars. Properties can vary, depending on the coal tar-to-epoxy ratio. The ideal compromise appears to be approximately 50/50. Coal tar epoxies are only available in black or dark brown. They cost less than straight epoxies and generally have better wetting properties, so they can be used on slightly less than perfect surface preparation. There are similar re-coating problems as for the two-pack epoxies. 

There are some interesting examples of industrial cleaners based on alkanesulfonates other than in the I I segment. The wetting properties and the stability against hydrolysis make possible a broad spectrum of tailor-made products for neutral, alkaline, and acid media as well. Examples are the cleaning of trucks, busses, railway fuel cars, and airplanes (Table 31). 

Dreger et al. [72] determined the wetting properties of the sodium salts of symmetrical secondary, secondary, isomeric secondary pentanol sulfates and... 

TABLE 26 Wetting Properties of Alcohol Ether Sulfates... 

A central task for modern surfactant types in household and cosmetic use is good applicational behavior—foaming, wetting properties, hardness sensitivity, and so on—combined with reasonable dermatological properties. This chapter will give an overview about one of these the sulfosuccinates (Fig. 1). 

TABLE 13 Wetting Properties of Sulfosuccinate Diesters According to the Draves Test (g/L to give 25-s wetting time)... 

The application of sulfosuccinates in the field of household products is limited. But when extremely-good wetting properties are desired the short C-chain dialkyl sulfosuccinates are used. Examples are special glass cleansers (beer glass cleaner, spectacle glass cleaner, windscreen cleaner), floor cleaner, and wallpaper stripper. The amount added to the formula is between 0.5% and 2.5%, although for wallpaper stripper up to 20% is used. A typical formulation for a glass cleaner is ... 

Note The dipping solution can also be used as a spray solution. RP layers should be treated with the methanol-containing reagent on account of its better wetting properties. In addition it is necessary, particularly after the use of acidic mobile phases, to spray with alkalis, e.g. pyridine, after the heat treatment step [2, 3]. 

Studies 6.le and f. Effect of water temperature on wetting properties... 

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