Foam Destruction Research Articles

Synthesis and properties of new fluorinated surfactants

New ionic and non ionic F-alkylated surfactants, well defined, monodisperses, were obtained and tested in various fields: Starting from F-alkylethens ionic surfactants such as ▪ hydrophilic head were obtained and used to obtain multipurpose OH fire fighting foams. The properties of these news foams (expansion rate, 25% décantation time, Foam destruction by fire of cyclohexane and ethanol) were estimated and compared with those obtained with commercial fluorinated surfactants. Starting for R FC 2H 4SH new non ionic monodisperse F-alkylated tensioactive agents such as: R FC 2H 4S(C 2H 4O) mC 2H 4S(C 2H 4) nH with R F = C 2F 5, C 4F 9, C 6F 13, C 8F 17 m = O, 1 or 2 n = 1, 2, 3 or 4 were synthetised by univocal ways. The obtention of homogenous series permitted us to define physico chemical parameters such as H.L.B., Haze point, Cloud Point, Phase inversion temperature to obtain fair microemulsions in the wished conditions. Zones of microemulsions were defined and influences of temperature, surfactant and fluorocarbon are discussed. Another application of these surfactants affects thermohardeness varnishes: When small quantities (0,2%) of such compounds is added to a thermohardener varnish for polycarbonates the resistance to abrasion in highly increased. Results are discussed.

Auslegung und Dimensionierung eines mechanischen Schaumzerstörers

AbstractDesign and dimensions of a mechanical defoamer. This paper presents a newly developed powerful mechanical defoamer which exploits centrifugal force and, thanks to circular channels, also Coriolis force for destruction of foam. It is incorporated into containers such that the expelled foam concentrate is deflected by the lid without producing fresh foam. Model experiments with three geometrically similar but different sized laboratory models led to dimensionaltheoretically formulated process‐relations of the defoamer for various material systems (five chemical foamers, two biological substrates). Such process‐relations represent a reliable basis for design and dimensions of the defoamer presented, on the one hand, and permit determination of an „intermediate characteristic”︁, having the dimensions of acceleration, which represents the mechanical degradability of the foam.

Reversible hypercholesterolaemia produced by cholesterol-free fish meal protein diets

Groups of rabbits were fed isonitrogenous diets containing 30% soya, milk or whitefish meal protein and at least 130 g/kg of added fat for 1 year. Mean serum cholesterol values in fish meal animals (13.4 ± 2.4 mmol/l) were substantially greater than for soya (3.0 ± 0.2 mmol/l) or milk (4.6 ± 0.7 mmol/l). Fish meal rabbits developed extensive aortic atherosclerosis (c. 70% surface involvement) which histologically showed both fibrous and foam cell intimal thickening and destruction and calcification of medial elastic tissue. In a second experiment fish meal was given with either saturated (coconut oil) or unsaturated (maize oil) fat. A similar degree of hypercholesterolaemia developed in each group and was rapidly reversed when a soya protein-low fat fiet was substituted. This model may therefore be of value in studies of the progression and regression of experimental atherosclerosis.

Influence of the pressure in the Plateau-Gibbs borders on the drainage and the foam stability

The effect of the pressure in the Plateau-Gibbs borders of the foam upon its drainage and its stability has been investigated. The principle of the method and the apparatus for applying pressure gradient in the Plateau-Gibbs borders of the foam are described. The kinetics of establishing of the capillary pressure in the Plateau-Gibbs borders of the foam in dependence of the height of the foam column, the applied pressure difference and the type of the surfactant has been studied. The obtained results are qualitatively confirmed by an investigation of the foam water content change (calculated by measurements of its specific conductivity) at the same experimental conditions. The influence of the increased drainage rate and respectively the decreased foam water content on the foam stability when a pressure gradient is applied in its Plateau-Gibbs borders is discussed. It is shown that the time for the foam destruction when a pressure gradient is applied in the foam Plateau-Gibbs borders can be used for characterising the foam stability at definite conditions.

Die Bedeutung der Schaumzerstörung bei der Kartoffelstärkegewinnung

The Significance of Foam Destruction for Potato Starch Production.During the production of potato starch destruction of the foam is inevitable at all stages of the process as it will interfere with the recirculation of the processing waters. This also affects the reduction of water consumption (related to the amount of raw material). The application of mechanical means or vapor for foam destruction is limited. Application of defoaming materials with simultaneous recirculation of floating and washing waters, two‐step separation of the fruit juice and rendering innocuous of the starch waste waters by activation has proved to be the most advantageous process.

Destruction of Fire-fighting Air Foam by High Temperature Petroleums

Destruction of Fire-fighting Air Foam by High Temperature Petroleums

Destruction of Foam in Volumetric Flasks

Destruction of Foam in Volumetric Flasks

Destruction of Foam in Volumetric Flasks

Destruction of Foam in Volumetric Flasks