Foaming Characteristics

Foaming Characteristics. When producing resol-type and benzylic ether-type foams, the index expresses apparent reactivity. Following are the foaming times  

CT Cream Time—the time required for the foamable mixture to become creamy after the reaction is started Gel Time—the time required for the inside of the mixture to become hard during foaming, whUe the outer surface begins to have spinability 

Rise Time— the time required for the rise of the mixture to be almost completed 

TFT Tack-Free Time—the time required for the mixture to become tack-free while it is rising or has finished rising 

These designations are used in polyurethane-foaming technology 

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Performance can be illustrated for example by the time necessary for deaeration or de-emulsification of oils, anti-rust properties, copper strip corrosion test, the flash point in closed or open cup, the cloud and pour points, the foaming characteristics, etc. 

Foaming characteristics of lubricating oils NFT 60-129 ISO/DIS 6247 ASTM D 892 Air sparging and measurement of foam after standing... 

The fully and super hydrolyzed PVA grades are preferred by the paper industry for their superior strength, greater adhesion to cellulose, better water resistance, and better foaming characteristics. However, the intermediate and partially hydrolyzed grades provide better surface filming characteristics on many paper and paperboard substrates. 

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). 

During each of the operations record all periinent information such as vacuum level, temperature, time required for the cake to crack, filtrate foaming characteristics, air flow rate during the drying periods, etc. 

For various foaming characteristics of the liquid of the system, Kister [190] reports a recommendation of W. L Bolles based on course lecmres at the University of New South Wales and the University of Sydney as follows ... 

Table 8-20 gives suggested downcomer clear liquid velocities based on relative foaming characteristics of the fluid on the tray at tray conditions. 

System Foaming Characteristics Allowable Clear Liquid Velocities, ft/sec High Medium Low... 

If foaming characteristics of the system are less than air-water, results will be conservative. For systems tending to greater foam and bubbles than the air-water system, approximate a value of h i by multiplying calculated value by 2, or 3 or known relative relationship. 

Dishwashing foam stability performance of an LAS-based light-duty liquid (LDL) is strongly affected by the carbon chain distribution, by water hardness, and, under some conditions, by phenyl isomer distribution. Foaming characteristics of C)2 phenyl isomer blends have been reported previously for conditions where LAS is the single anionic surfactant in the formulation (phosphate-built laundry powder) and the level of residual water hardness is low [30,31]. Under these conditions the internal phenyl isomers of C,2 LAS gave better foam performance than the 2-phenyl isomer. 

Tallow alcohol sulfate is an important surfactant used in heavy-duty detergents. The unsaturated part of the alkyl chain of tallow alcohol gives their sulfates an improved solubility with excellent detergent and foaming characteristics. 

Lithium alcohol sulfates are used in carpet-cleaning formulations due to their special foaming characteristics. 

TABLE 9 Foaming Characteristics of Mixtures of Na Lauryl Ether Sulfate (SLES + 2 EO) and Na Lauryl Ether Carboxylate (Cl2-C 4 13 EO CH2COONa) According to R M... 

Alkyl sulfates and alcohol ether sulfates have been established for use in emulsion polymerization. AOS, although it has been used for many detergent applications during the past four decades, does not find any large-scale use as a primary surfactant system in emulsion polymerization. A study by Kreis [92] has shown that AOS surfactants are very well able to produce a small size latex and have excellent foaming characteristics (i.e., foam height and stability) in latex. They should therefore be able to compete with alkyl sulfates and alcohol ether sulfates. 

AEs have found application in all kinds of domestic and institutional detergents, and cleaning agents. Their low foaming characteristics, better electrolyte compatibility and degreasing capacity relative to anionic surfactants make them especially attractive for use in I I products [18]. Furthermore, they are applied in cosmetics, agriculture, and in the textile, paper and oil industries. They have become increasingly important in more recent years, due to efforts to replace APEO. 

Rodriguez Patino, J.M., Rodriguez Nino, M.R., Gomez, J. (1997). Interfacial and foaming characteristics of protein-lipid systems. FoodHydrocolloids, 11, 49-58. 

Many methods have been used to produce and characterize protein foams. The foaming characteristics of proteins are markedly influenced by conditions of preparation, measurement, and so forth (13-18). Because of the variety of methods employed, it is difficult to compare data from different sources. 

In the reaction shown in Figure 2.6, assume that we are beginning with a PPG with a molecular weight of 1000. There are two hydroxyls (the equivalent weight of the PPG is 500). Two moles of TDI per mole of PPG are required. For 1 kg of PPG, therefore, 542 grams of TDI are required. Excess is usually added to maintain a reasonable reaction rate. Very often, if foam is the desired final product, excess isocyanate is intentionally added to improve the foam characteristics. In that case, the prepolymer is designated as a quasi- or semiprepolymer. 

BP Research Centre at Sunhury investigated the foaming characteristics of the crude and developed, with others, a novel foam inhibitor that effectively prevented foam generation in the separators... 

Brent crude had similar, but less severe, foaming characteristics. These problems were solved in the same way as those with the Ninian crude. 

The Ninian pipeline crude comes from two fields, while the Brent pipeline crude is from five fields. The properties of ihe crudes from each field are different, particu laily the foaming characteristics. 

Effects of Livening lip Crudes on Foaming Characteristics. Partial Rexassing of S inian Crude. Once steady control of foaming in the dead crude mode had been... 

Investigation of foaming characteristics of crudes and effectiveness of anti-foam chemicals should he conducted at an early stage of the design of gas/oil separators to assess the economics of extra residence time (larger separation vessels) vs. anti-foam chemical injection as the means of preventing foam... 

Townsend, A.-A. and Nakai, S. 1983. Relationships between hydrophobicity and foaming characteristics of food proteins. J. Food Sci. 48 588-594. 

This ability to generate foams finds use in beverages such as ginger beer, shandy, cream soda and cola formulations to improve and standardise heading foam characteristics. 

Foam characteristics in several commercial beers were evaluated using one-dimensional NMR image. Foam texture differences and regions of cling, head, and liquid beer can be clearly distinguished. Significant differences in rates of foam collapse were measured [22]. 

In order to overcome this drawback, the concept of selective blending was exploited. Selective blending of PPE with low-viscous PS allowed one to control the microstructure, to refine the phase size, and to adjust the foaming characteristics of the individual phases of PPE/SAN blends. Appropriate blend compositions allowed simultaneous nucleation and cooperative expansion of both phases, generally leading to bimodal cell size distributions in the micron range. Due to cell nucleation and growth in both blend phases, the density could be further reduced when compared to PPE/SAN blends. Moreover, the presence of coalesced foam structure and particularly macroscopic defects could be avoided, and the matrix of the foamed structure was formed by the heat resistant PPE/PS phase. 

Hu, P.C. (1992). Foaming characteristics of alpha olefin sulphonate and its components. Proceedings 3rd CESIO International Surfactants Congress, vol. D, pp. 334 17. 

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