Dispersed foams, drying

The physicochemical state of fat in milk powder particles, which markedly influences the wettability and dispersibility of the powder on reconstitution, depends on the manufacturing process. The fat occurs either in a finely emulsified or in a partly coalesced, de-emulsified state. In the latter case, the membrane has been ruptured or completely removed, causing the globules to run together to form pools of free fat. The amount of de-emulsified free fat depends on the manufacturing method and storage conditions. Typical values for free fat (as a percentage of total fat) in milk powders are spray-dried powders, 3.3-20% roller-dried powders, 91.6-95.8% freeze-dried powders, 43-75% foam-dried powders, less than 10%. 

Combustible liquid flash point (closed cup) 54°C (130°F), (open cup) 68 C (155°F) vapor pressure 31 torr at 25°C (77°F) vapor density 2.5 (air = 1) autoignition tempera-tnre 360°C (680°F). Vapors of acrylic acid form explosive mixtures with air within the range 2.9-8.0% by volume in air. Fire-extingnishing agent water spray, alcohol foam, dry chemical, or CO2 nse a water spray to flnsh and dilute the spill and to disperse the vapors. 

Highly flammable flash point (open cup) -18°C (-0.5°F) (Aldrich 1989), closed cup -36°C (-33°F) vapor pressure 214 torr at 20°C (68°F) vapor density 1.93 (air = 1) vapor may travel a considerable distance to a source of ignition and flash back autoignition temperature 234°C (453°F) (unstable) fire-extinguishing agent alcohol foam, dry chemical, or CO2 use a water spray to keep the fire-exposed containers cool, to flush and dilute the spill, and to disperse the vapor. 

Highly flammable flash point (closed cup) —15°C (—5°F) ignition temperature 515°C (959°F) vapor density at 38°C (100°F) 1.6 (air = 1) the vapor may travel a considerable distance to an ignition source and flash back fire-extinguishing agent foam, dry chemical, or CO2 water sprays may be used to flush any spill, disperse the vapors,... 

Aside from aforementioned hybrid technologies, there are two basic techniques for convective drying of foamed materials, namely, drying of bulk foams (foam-mat drying) and drying of dispersed foams (spray drying). 

In spray drying, a gas-admixing technique is used to produce a dispersed foam from the feed, whereas in foam-mat drying mechanical methods (e.g., mixing, whipping) are applied to stabilize a bulk volume of the foamed raw material. 

Bell, R. W., Hanrahan, F. P Web, B. H., 1963. Foam spray drying methods of making readily dispersible nonfat dry milk./. Dairy Sci. 46 1352-1356. 

Uses Foaming agent and suspending agent in rock drilling, fire fighting dispersant for dry wall mfg., dyes and pigments... 

Uses Detergent, foam booster, emulsifier, welling agent, dispersant for dry bubble baths, powd. hand soaps. It. duty and fine fabric detergents, metal soak cleaners, aerosol mg and upholstery cleaners ftroperf/es Flake M% cone. 

BIO-SOF EN600 Stabilizer, foam dispersants Hetamide MMC, OC Laurie acid Stabilizer, foam dressings Avicel CL-611 Avice RC-581 Stabilizer, foam dry cleaning Noifox DCSA Norfox DGCA Stafoam DL... 

Classically, aerosols are particles or droplets that range from about 0.15 to 5 p.m ia size and are suspended or dispersed ia a gaseous medium such as air. However, the term aerosol, as used ia this discussion, identifies a large number of products which are pressure-dispensed as a Hquid or semisohd stream, a mist, a fairly dry to wet spray, a powder, or even a foam. This definition of aerosol focuses on the container and the method of dispensiag, rather than on the form of the product. 

Urea.—Forma.IdehydeResins. Cellular urea—formaldehyde resins can be prepared in the following manner an aqueous solution containing surfactant and catalyst is made into a low density, fine-celled foam by dispersing air into it mechanically. A second aqueous solution consisting of partially cured urea—formaldehyde resin is then mixed into the foam by mechanical agitation. The catalyst in the initial foam causes the dispersed resin to cure in the cellular state. The resultant hardened foam is dried at elevated temperatures. Densities as low as 8 kg/m can be obtained by this method (117). 

Apphcation chemists are most interested in physical and functional properties contributed by the sulfonate moiety, such as solubility, emulsification, wetting, foaming, and detersive properties. Products can be designed to meet various criteria including water solubility, water dispersibility, and oil solubility. The polar SO moiety contributes detersive properties to lube oil sulfonates and dry-cleaning sulfonates. 

A chemical blowing agent was well dispersed in a linear low density polyethylene matrix, in pellet form. The pellets were rotationally moulded to produce foams, the morphology of the foams being studied using optical microscopy. The quality of the cell structures in terms of cell size, cell population density and volume expansion ratio was superior to that of foams produced by drying blending. 28 refs. 

For the preparation of the foam, a solution of 1 g technical sodium diisobutyl naphthalene sulfonate in 50 ml of 3% orthophosphoric acid is prepared. 20 ml of this solution are poured into a 11 beaker and air is stirred in with a fast running mixer until the cream-like dispersion has reached a volume of 300-400 ml.Then,20 ml of the prepared urea/formaldehyde resin are mixed in, whereby the resin must be evenly distributed. After 3-4 min the introduced resin gellifies into a molded article permeated with many water/air pores under the influence of the acidic catalyst. After 24 h,the crosslinking is completed. Drying for 12 h at 40 °C in a circulating air dryer yields a brittle thermoset foam.The foamed plastic obtained is hydrophobic and has a large internal surface. It can take up about 30 times its own weight of petroleum ether. 

By far the most studied PolyHIPE system is the styrene/divinylbenzene (DVB) material. This was the main subject of Barby and Haq s patent to Unilever in 1982 [128], HIPEs of an aqueous phase in a mixture of styrene, DVB and nonionic surfactant were prepared. Both water-soluble (e.g. potassium persulphate) and oil-soluble (2,2 -azo-bis-isobutyronitrile, AIBN) initiators were employed, and polymerisation was carried out by heating the emulsion in a sealed plastic container, typically for 24 hours at 50°C. This yielded a solid, crosslinked, monolithic polymer material, with the aqueous dispersed phase retained inside the porous microstructure. On exhaustive extraction of the material in a Soxhlet with a lower alcohol, followed by drying in vacuo, a low-density polystyrene foam was produced, with a permanent, macroporous, open-cellular structure of very high porosity (Fig. 11). 

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