Foam aerosols

Gas Liquid Solid — Foam Aerosol Emulsiom Aerosol Suspension Solid foam Solid emulsion Solid disersion... 

Aerosol foam Aerosol OT Aerosol packaging Aerosol paints Aerosol propellants Aerosols... 

Aerosols. Pressurized containers to deHver aerosolized dmg products through appropriate systems of valves and actuators have been available since the 1950s (see Aerosols). Such dosage forms are used as external appHcations of lotions and creams, for oral inhalation, or for treatment of the vaginal cavity, eg, contraceptive foams. Aerosols contain two- or three-phase systems, wherein a volatile Hquid or admixture of Hquids is sealed in a... 

HCFC-22 chcif2 Industrial refrigerant, manufacturing of polymers, polystyrene foams, aerosol sprays... 

Other organics Toluene diisocyanate Polyurethane foam aerosols... 

One characteristic of phase boundaries, especially those involving an aqueous phase, is the probable existence of an electrical potential across the interface. Although such charge phenomena an not always present, when in existence, they have an enormous impact on system properties. Chargi effects are usually most important in aqueous suspensions, emulsions, foams, aerosols, and othe dispersions in which one phase is Lnely divided in another phase, creating a large interfacial area. 

Table 15.4 Illustration of some personal care foam aerosol" product formulations...

A flammable aerosol is classified in one of the two categories for this Class on the basis of its components, of its chemical heat of combustion and, if applicable, of the results of the foam test (for foam aerosols) and of the ignition distance test and enclosed space test (for spray aerosols). See decision logic in 2.3.4.1. 

For spray aerosols, go to decision logic 2.3 (b) For foam aerosols, go to decision logic 2.3 (c) ... 

In disperse systems where coagulation and coalescence occur with very low rates, and under the conditions of substantial solubility of dispersed matter, the decrease in degree of dispersion may be caused by the matter transfer from smaller particles to the larger ones. These processes are quite common in nature and may take place in a variety of disperse systems, such as lyosols, suspensions, emulsions, foams, aerosols, in the systems with solid... 

Sensitisation may be produced by non-occupational environmental exposure. For example, three subjects were shown to be TDI sensitive by the simulated occupational test, where the causal exposure was from the exhaust fumes from an adjoining factory which had been sucked into the ventilating system of their warehouse. TDI was found in the air filters (Carroll et al. 1976). Sensitisation at home by two-can do it yourself polyurethane-TDI foam aerosol cans (Peters and Murphy 1971) and other forms of domestic exposure have been reported. Patients of this sort would, in the absence of histories of sensitivity or reactions to the common allergens, and the adult (late) onset of their asthma, be classified as having cryptogenic (intrinsic) asthma. The extent to which sensitivity of this sort to chemical environmental pollutants may be responsible for some cases of cryptogenic asthma will obviously need to be determined. 

Obviously, knowing how colloids can be stabilized provides an invaluable tool for the preparation of many useful systems. It also can provide clues to how an unwanted colloid can be destabilized and removed. The above-mentioned ideas, at times in a slightly different guise, will appear again in the following chapters on emulsions, foams, aerosols, and similar compounds. 

Interfacial effects are especially important in systems where interfadal area is large. This condition is met when one phase is dispersed in another as small drops or particles. With spherical particles, for example, the arearvolume ratio of the dispersed phase is (3/R), where R is the partiele radius. Qearly as R decreases with a given volume of the dispersed matraial present, interfadal area increases. When at least one dimension of each drop or particle decreases to a value in the range of 1 /rm or less, we say that a eoUoidal dispra ion exists. Foams, aerosols, and emulsions are colloidal dispersions involving fluid interfaces that are familiar from everyday life and are important in applieations ranging from food products... 

Dispersions include emulsions, foams, aerosols and suspensions (Table 8.18). In all cases an outer, continuous phase is distinct from an inner, discontinuous, dispersed phase. Emulsions are of particular importance and they will be outlined in more detail. 

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