Foam diagrams

Fig. 6-11. Schematic diagram of the kraft pulping process (6). 1, digester 2, blow tank 3, blow heat recovery 4, washers 5, screens 6, dryers 7, oxidation tower 8, foam tank 9, multiple effect evaporator 10, direct evaporator 11, recovery furnace 12, electrostatic precipitator 13, dissolver, 14, causticizer 15, mud filter 16, lime khn 17, slaker 18, sewer.

However, the fundamental theory of simple foams is not as well formulated as the theory for simple emulsions. Because foams consist of gases dispersed in a semisolid film, the properties and behavior immediately become more dramatically subject to external variables, such as temperature and external air pressure. Minute changes in surface tension of the film can make or break the foam. However, a similar approach might be suggested in the foam field. In this case, the variable with which we are most concerned is whether or not a stable foam is produced and the diagrams would be drawn accordingly. 

Figure 12.7 Schematic diagram showing the role of LDL glycatlon and oxidation in foam-cell formation [adapted from Lyons (1991) and Esterbauer et al. (1992)]. C, cholesterol CE, cholesterol ester.

Figure 25.8 Schematic diagram outlining the general process for making foamed polyurethane slabstock... 

Figure J.. Schematic representation of the flow diagram of the foam rheology rig.

The mechanical response of polypropylene foam was studied over a wide range of strain rates and the linear and non-linear viscoelastic behaviour was analysed. The material was tested in creep and dynamic mechanical experiments and a correlation between strain rate effects and viscoelastic properties of the foam was obtained using viscoelasticity theory and separating strain and time effects. A scheme for the prediction of the stress-strain curve at any strain rate was developed in which a strain rate-dependent scaling factor was introduced. An energy absorption diagram was constructed. 14 refs. 

Flow diagram of the manufacturing process for polyolefin foams using radiation cross-linking. 

As an example, patterns and transitions are indicated in Figure 5.2-3 for cylindrical (1x5 mm) and spherical (2.4 and 3 mm) alumina catalyst pellets with nitrogen and different foaming and non-foaming hydrocarbon and viscous organic liquids. This diagram covers the fluid properties range ... 

Other flow charts did not lead to a better agreement with experimental data at different pressures. Larachi et al. [19] have suggested the use of a modified Charpentier s diagram. Based on experimental data available to date on the high-pressure trickle-pulsed transition, the extended diagram is proposed to quantify directly the effect of pressure in non-foaming systems. 

The principle of composition of three-phase syntactic foams can be represented by a ternary phase diagram (Fig. 7). Point A on the diagram denotes a composite of the following volume fractions resin 0.15, microspheres 0.60, voids 0.2586>. The pure void free syntactic foam has a two-phase composition which falls along the... 

Fig. 7. Phase diagram of three-component syntactic foam 86)...

Another two-phase composite is chemically or physically blown foam, composed of polymer and voids only (i.e. conventional foamed or cellular polymer). Its compositions lie along the polymer-void border of Fig. 7, and it, too, is limited by the maximum volume fraction of voids allowed, while still maintaining the definition of a foam. The limits mentioned define the allowed compositions for syntactic foams and determine the area within the diagram where they are located. One limiting case is point B which represents the composition of microspheres (0.74), polymer (0.11), and voids (0.15). The microspheres, in this case, are arranged in a hexagonal close packing 85). 

Fig. 21. Compression diagram for (1) an epoxy syntactic foam with phenolic microspheres and (2) unfilled epoxy resin 1611...

The presence of mixed surfactant adsorption seems to be a factor in obtaining films with very viscous surfaces [411]. For example, in some cases the addition of a small amount of non-ionic surfactant to a solution of anionic surfactant can enhance foam stability due to the formation of a viscous surface layer, which is possibly a liquid crystalline surface phase in equilibrium with a bulk isotropic solution phase [25,110], In general, some very stable foams can be formed from systems in which a liquid crystal phase is present at lamella surfaces and in equilibrium with an isotropic interior liquid. If only the liquid crystal phase is present, stable foams are not produced. In this connection foam phase diagrams may be used to delineate compositions that will produce stable foams [25,110],... 

Fio. 17. Computer generated structure of hexagonal and random closed-cell foam obtained by Voronoi tessellation, shown as voxel representation of phase function (left), and network diagram where nodes correspond to cells and bonds to cell walls (from Salejova et ah, 2005). 

Phase diagrams of DMPC foam bilayers. The analysis of the experimental results for the foam bilayer thickness and the critical concentration for formation of the foam bilayer... 

Fig. 3.97. Phase diagram of DMPC foam bilayers formed from aqueous solutions containing 47.5 vol.%...

Undoubtly, phase diagrams are the most convenient. The above discussed is in fact the first attempt to construct such a diagram for foam bilayers. Phase diagrams of surfactant solutions indicating the system state can be found in the monograph of Laughlin The Aqueous Phase behaviour of Surfactants [455] and are of major practical importance. 

It seems promising to estimate the stabilising ability of surfactant mixtures analysing their phase diagrams [76,77]. The comparison between the surfactant state in the bulk phase and the foam stabilising ability allows not only to choose the most suitable foaming agents but also to clarify the main reasons for foam stability. 

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