Hydrophile-lipophile balance temperature

Hydrophilic-lipophilic balance (HLB), 24 143, 155-156 in paper recycling, 21 436 Hydrophilic-lipophilic balance temperature, 16 430... 

The temperature (or salinity) at which optimal temperature (or optimal salinity), because at that temperature (or salinity) the oil—water interfacial tension is a minimum, which is optimum for oil recovery. For historical reasons, the optimal temperature is also known as the HLB (hydrophilic—lipophilic balance) temperature (42,43) or phase inversion temperature (PIT) (44). For most systems, all three tensions are very low for Tlc < T < Tuc, and the tensions of the middle-phase microemulsion with the other two phases can be in the range 10 5—10 7 N/m. These values are about three orders of magnitude smaller than the interfacial tensions produced by nonmicroemulsion surfactant solutions near the critical micelle concentration. Indeed, it is this huge reduction of interfacial tension which makes micellar-polymer EOR and its SEAR counterpart physically possible. 

Kunieda, H. and Shinoda, K. (1980) Solution behaviour and hydrophile-lipophile balance temperature in the Aerosol OT-isooctane-brine system-correlation between microemulsions and ultralow interfacial tensions. /. Colloid Interface Sci., 75, 601-606. 

Phase behavior in systems of nonionic surfactant/water/oil around the hydrophile-lipophile-balance-temperature (HLB-temperature). /. Dispersion Sci. Tecknol., 3, 233-244. 

Kanei, N., Tamura, Y. and Kunieda, H., Effect of types of perfume compounds on the hydrophile-lipophile balance temperature, J. Colloid Interface ScL, 218, 13-22 (1999). 

In most cases, these active defoaming components are insoluble in the defoamer formulation as weU as in the foaming media, but there are cases which function by the inverted cloud-point mechanism (3). These products are soluble at low temperature and precipitate when the temperature is raised. When precipitated, these defoamer—surfactants function as defoamers when dissolved, they may act as foam stabilizers. Examples of this type are the block polymers of poly(ethylene oxide) and poly(propylene oxide) and other low HLB (hydrophilic—lipophilic balance) nonionic surfactants. 

Lipids with a suitable hydrophilic-lipophilic balance (HLB) are known to spread on the surface of water to form monolayer films. It is obvious that if the lipid-like molecule is highly soluble in water, it will disappear into the bulk phase (as observed for SDS). Thus, the criteria for a monolayer formation are that it exhibits very low solubility in water. The alkyl part of the lipid points away from the water surface. The polar group is attracted to the water molecules and is inside this phase at the surface. This means that the solid crystal, when placed on the surface of water, is in equilibrium with the him spread on the surface. A detailed analysis of this equilibrium has been given in the literature (Gaines, 1966 Adamson and Gast, 1997 Birdi, 2009). The thermodynamics allows one to obtain extensive physical data on this system. It is thus apparent that, by studying only one monolayer of the substance, the effect of temperature can be very evident. 

At low temperature, nonionic surfactants are water-soluble but at high temperatures the surfactant s solubility in water is extremely small. At some intermediate temperature, the hydrophile—lipophile balance (HLB) temperature (24) or the phase inversion temperature (PIT) (22), a third isotropic liquid phase (25), appears between the oil and the water (Fig. 11). The emulsification is done at this temperature and the emulsifier is selected in the following manner. Equal amounts of the oil and the aqueous phases with all the components of the formulation pre-added are mixed with 4% of the emulsifiers to be tested in a series of samples. For the case of an o/w emulsion, the samples are left thermostated at 55°C to separate. The emulsifiers giving separation into three layers are then used for emulsification in order to find which one gives the most stable emulsion. 

K. Shinoda and H. Takeda, The effect of added salts in water on the hydrophile-lipophile balance of nonionic surfactants the effect of added salts on the phase inversion temperature of emulsions, J. Colloid Interface Sci. 32 (1970) 642-646. 

The Span 80 with an HLB (hydrophilic-lipophilic balance number) of 4,3, which is an oil soluble liquid, was used as surfactant. The effect of the continuous medium was investigated by employing 1,1,2,2-tetrachloroethane, toluene, or decane, which have various degrees of hydrophobicity. The amounts of the components used are listed in Table 3. At room temperature (20 °C), concen-... 

Attenuated total reflection infrared critical micelle concentration electron spectroscopy for chemical analysis hydrophilic-lipophilic balance poly(chlorotrifluoroethylene) poly(dimethylsiloxane) poly(tetrafluoroethylene) poly(trifluoropropylmethylsiloxane) glass transition temperature critical surface tension of wetting Owens-Wendt solid surface tension surface tension of aqueous solution surface tension of liquid... 

P gives a measure of the hydrophilic-lipophilic balance. For values of P < 1 (usually P l/3), normal or convex aggregates are produced (normal micelles), whereas for values of P > 1 inverse micelles are produced. P is influenced by many factors, including the hydrophilicity of the head group, the ionic strength and pH of the medium, and temperature. 

Four different emulsifier selection methods can be applied to the formulation of microemulsions (i) the hydrophilic-lipophilic-balance (HLB) system (ii) the phase-inversion temperature (PIT) method (iii) the cohesive energy ratio (CER) concept and (iv) partitioning of the cosurfactant between the oil and water phases. The first three methods are essentially the same as those used for the selection of emulsifiers for macroemulsions. However, with microemulsions attempts should be made to match the chemical type of the emulsifier with that of the oil. A summary of these various methods is given below. 

Kunieda, H., and Miyajima, A. (1989) The effect of the mixing of oils on the hydrophile-lipophile-balanced (H LB) temperature in a water/non-ionic surfactant/oil system. /. Colloid Interface Sci, 128, 605-607. 

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