Total one phase area

FIGURE 5.3 Variation of the total one-phase area (A. ) as a function of ethoxylated mono-di-glyceride/sucrose laurate mixing ratios (w/w) in water/sucrose laurate/ethoxylated mono-di-glyceride/oil systems at 25°C. The oils were R (-i-)-LIM and IPM. The lines serve as guides to the eyes. 

Soybean oil was supplied by Procter and Gamble Inc., Toronto, Ontario, Canada. Methyl ester was made by the one-phase method employing a methanol/oil molar ratio of 27 1, tetrahydrofu as cosolvent and 1.0 wt.% sodium hydroxide based on the oil. The methyl ester accounted for 99,7% of the total ester present. The Alcan AA 200 activated alumina used was supplied by Alcan Chemicals, Brockville. Ontario, Canada. The catalyst s BET surface area is 270-290 /g, and its pore volume is 40 cmVg. The pore distribution is binodal, with 66% of pore volume in pores Jess than 30 radius and the rest in larger pores. Its bulk density is 0.75 g/cm... 

Precipitation of the growing polymer from the initial solution of styrene and DVB in an inert diluent during crosshnking copolymerization results in the formation of a two-phase heterogeneous network, in which one phase is presented hy the highly crosshnked and rigid polymer, while the rejected diluent forms another phase. After removing the diluent, permanent voids remain in the copolymer beads. The total pore volume, and the inner surface area, S, are the major characteristics of the porous structure these are intimately related to pore size and pore size distribution. These parameters determine the practical apphcation frelds of the polymeric adsorbent resins therefore, a precise quantitative characterization of resin porosity becomes an important task. 

It seems in Fig. 2g that all the experimental points are lying on a master surface, which is a first indication that there might be a physical law describing the correlation between the pore size and the molecular architecture of the amphiphile. However, because neither the one-phase nor the two-phase model was appropriate to describe the data (as shown elsewhere)," a new model was needed. It seems that in addition to the hydrophobic core (bright yellow), a certain fraction of the hydrophilic poly(ethylene oxide) (PEO) chain contributes to the size of the mesopore Dc (areas I and H in Fig. 3c). Only the remaining fraction of PEO is imbedded in the pore wall. By considering the total volume given by the number of units in the amphiphile chain and the stabilization of the interface I + II/III, it was finally possible to derive an equation that relates the mesopore size to the molecular composition of the amphiphile expressed as Vvb (see Eq. 1) ... 

We end this section by summarizing the areas where we feel that the NMR diffusion method will prove important in future studies of emulsions and refer to a more detailed account presented in Chapter 10 of this book. As theories describing emulsion stability become more refined, there will be a need for data on droplet size distribution and also on total emulsion droplet area and how these quantities evolve with time. As outlined above, NMR is eapable of providing sueh data. Another important question pertains to the mi-crostrueture of the continuous phase, which can be studied both in the emulsion phase and also in the phase-separated systems which yield the emulsion. Finally, we note that one important class of emulsions, namely, multiple emulsions, is practically virgin territory with regard to NMR studies. In the characterization and understanding of important features of these systems NMR will most likely play an important role. 

Micro-emulsion polymerization In micro-emulsion polymerization, the initial system is microemulsion which consist of monomer droplets (varying from 10 to 100 nm) dispersed in water with the aid of a classical emulsifier (e.g. sodium dodecyl sulfate, SLS) and a "cosurfactant" such a low molar mass alcohol (pentanol or hexanol). Micro-emulsions are thermod3mamically stable and optically one-phase solution. There is an excessive amount of emulsifier in these emulsions. Therefore, they are concentrated systems of micelles and the micelles exist throughout the reaction. One of the most interesting aspects of these micelles is their ability to accommodate monomer molecules. Furthermore, their high total surface area relative to nucleated particles implies the monomer-swollen micelles preferentially capture primary radicals generated in the continuous aqueous phase. Then the probability... 

Although interfaces usually constitute a small fraction of the total volume of a composite, the effects of their properties on the bulk properties are large because of the large surface area of the interfaces. The properties of the interface depend on whether or not there has been a reaction at the interface, the type of bonding at the interface, and on the nature (crystalline or amorphous) and morphology of the interface material. The consequences of having a smooth versus a rough interface are far more important in structural applications where one phase, such as a fiber, must be able to slide out of the matrix to some extent, in order to achieve optimum mechanical behavior. 

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