Foam stability definition

However, it should be noted that this dependence does not yield a firm criterion of foam stability with respect to its internal collapse [22], Indeed by definition the rate of internal collapse is expressed as... 

Definition of the Term Foam Stability and Foaming Ability of Solutions... 

In one of the first attempts to explain foam stability in terms of thermodynamics it was assumed that the foam lifetime depends on the decrease in surface energy and increases when a definite value of A a is reached [e.g. 34],... 

It is well know that the direct comparison between the methods of estimation of foam stability (in most of the cases it is determined by the foam lifetime) is not possible. Each of the existing methods involves different parameters, for example, time for destruction of a foam column of a definite height (or part of it), rate of decrease in the specific foam surface, etc. The main reason for the impossibility to make such a comparison is that foam stability is determined at different pressures in the foam liquid phase. This means that the rate of drainage as well as the time of reaching an equilibrium state of the films in the foam is different. Another reason could be attributed to the possibility both foam formation (i.e. foam volume... 

Examples of industrial relevance for the first two combinations are the adsorption of pollutants from waste air or water onto activated carbon. Combinations three and four can be observed at the orientation of tensid molecules on water/air interfaces (foam formation, foam stabilization) or at the interface of two immiscible liquids, (e.g. oil and water, emulsion formation). This book deals mainly with the case of liquid molecules adsorbed onto solid surfaces. For this case the following definitions are made ... 

Definition Polymer of ethylene oxide Formula H(OCH2CH2)nOH, avg. n = 240 Uses Humectant in cosmetics foam stabilizer in fermented malt beverages ... 

Definition Polymer of ethylene oxide Formula H(OCH2CH2)nOH, avg. n = 350 Uses Lubricant for rubber molds, textile fibers, metalworking binder, solvent in cosmetics hair preps. pharmaceutic aid In gas chromatography In paints paper coatings polishes ceramics foam stabilizer in fermented malt beverages In food-pkg. adhesives... 

Synonyms POE (3) coconut amine Definition PEG deriv. of cocamine Formuia RN(CH2CH20)xH(CH2CH20)yH, R rep. alkyl groups from coconut oil and avg. (x+y) = 3 Toxicoiogy TSCA listed Uses Emulsifier in cosmetics lubricant, foam stabilizer, dispersant, vise, control agent for shampoos, hair colors Trade Name Synonyms Lowenol C-243 [Lowenstein Dyes Cosmetics http //www.jhlowenstein. com]... 

CAS 8013-05-6 EINECS/ELINCS 232-388-4 Synonyms Castor oil, potassium salt Fatty acids, castor oil, potassium salts Definition Potassium salt of fatty acids derived from castor oil Toxicology TSCA listed Uses Surfactant in cosmetics emulsifier dispersant mild germicide glycerized rubber lubricant emulsifier, foam stabilizer for... 

Definition Mixt. of ethanolamlnes of fatty adds from almond oil Formula RCO-N(CH2CH20H)2, RCO- rep. fatty acids from almond oil Uses Conditioner, vise, builder, foam stabilizer, surfactant In cosmetics Almond amide propylbetaine. See Almondamidopiopyl betaine Almond amides, N,N-bis (2-hydroxyethyl)-. See Almondamide DEA Almond amides, N-[3-(dimethylamino) propyl], N-oxide. See Almondamidopro-pylamine oxide... 

Definition Mixture of ethanolamides of fatty acids derived from mink oil Formula RCO-N(CH2CH20H)2, RCO- represents fatty acids derived from mink oil Uses Surfactant, foam builder, vise, builder, foam stabilizer in cosmetics Uanuf/Distrib. Nanjing Chemlin Variati Minkamide propylbetaine. See Minkamidopropyl betaine Minkamidopropalkonium chloride CAS 124046-06-6... 

Definition Mixture of elhanolamides of fatly acids derived from olive oil Formuia RC0-N(CH2CH20H), RCO- represents fatty acids derived from olive oil Uses SurfaclanL vise. buHder, foam stabilizer for cosmetics ManufJDistrib. mersel Cosmetic Co. Variati OIKramidopropalkonium chloride Ciassification Quaternary ammonium sail Uses Conditioner, foaming agenL slip agent for hair care Olivamidopropylamine oxide CAS 124046-32-8... 

Although most colloidal dispersions are not thermodynamically stable, a consequence of the small size and large surface area in colloids, and of the presence of an interfacial film on droplets, bubbles or particles, is that dispersions of these species, having reasonable kinetic stability, can be made. That is, suspended droplets or particles may not aggregate quickly nor settle or float out rapidly and droplets in an emulsion or bubbles in a foam may not coalesce quickly. Many food and personal care product emulsions and suspensions, for example, are formulated to remain stable for months to years. It is crucial that stability be understood in terms of a clearly defined process, and one must consider the degree of change and the time-scale in the definition of stability. 

The correlation between the stability of single O/W emulsion films, single drops under oil/water interfaces and real emulsions found in [514,516] also deserves attention. As revealed in the beginning of this Section the correlation between emulsions and emulsion films was studied in various aspects and always provide information about stability of such systems. Model studies of emulsion systems are worth further development especially if the correlation films/real emulsion is done at definite conditions which are as close as possible in both cases, for example, at equal capillary pressure, film size, emulsion dispersity, etc., as it is done in the correlation foam films/foam (see Chapter 7). 

The authors of this monograph consider reasonable to express foaming ability as the foam volume obtained from a known solution volume under defined conditions (temperature, surfactant concentration, mode of foam formation). As a more general characteristic of the ability of the surfactant solutions to form foams with a definite stability it is suitable to use the terms stabilising ability or foaming property. The volume of the foam obtained and its lifetime can serve as a qualitative measure for the latter. A more detailed estimation requires the use of a number of characteristics including drainage, internal foam collapse, etc. 

Foam inhibition is evaluated by the following procedure a definite quantity of the antifoam is added (usually - 0.1 cm3) to the foaming solution (100 cm3). Solid and paste-like antifoams are introduced as solutions. The time needed to fill up the foam vessel as well as the average foam lifetime with Tm and xam, respectively, with and without antifoams, are measured. It is convenient to express the foam inhibition ability either as the relative stability Tre[ (Eq. (9.2)) or as the defoaming coefficient [16]... 

The stability of both foam films and the foam, plays an important role in the effective application of the foams. They should satisfy special requirements for stability which might differ significantly even within the same group. Several techniques for controlling the quality of the products, for example, of beer, tea and whisky [8], or the tightness of pipe and reservoir welds, are based on the formation of a foam with a definite lifetime. 

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