Emulsification rate curves

The emulsification rate curves were also determined using the technique described by Surland (16). 

An examination of the emulsification rate curves indicates that most of the inks had an acceptable curve shape with the exception of ink C-l, which shows a "B" type shape (no equilibrium reached). All six inks were commercially acceptable in dot resolution although there were noticeable differences from the best to the poorest (Figure 9). Figure 10 shows photomicrographs of star targets printed with the inks rated at the two extremes, A1 and C4. A dot resolution rating of 7.0 is considered of normal commercial quality while the rating of 9.5 for ink C-4 is quite exceptional. 

Ink C-l, however, shows some anomalous behavior in that the shortness ratio of the emulsified ink is higher than C-4 whereas ink C-4 gave somewhat better dot resolution. A possible explanation of this is the anomalous emulsification rate curve of C-l previously mentioned, which indicates no attainment of equilibrium up to the 10 minute limit. The dot resolution results obtained with C-4, on the other hand, are consistent with the ideal emulsification curve shape which it exhibited. 

The shape of the emulsification rate curves is related to press performance of a lithographic ink. 

Studies of flow-induced coalescence are possible with the methods described here. Effects of flow conditions and emulsion properties, such as shear rate, initial droplet size, viscosity and type of surfactant can be investigated in detail. Recently developed, fast (3-10 s) [82, 83] PFG NMR methods of measuring droplet size distributions have provided nearly real-time droplet distribution curves during evolving flows such as emulsification [83], Studies of other destabilization mechanisms in emulsions such as creaming and flocculation can also be performed. 

According to O Donnell et al. [130], the emulsion polymerization of vinyl acetate follows the Smith-Ewart theory of emulsion polymerization [131] because the rate of polymerization is independent of the total amount of monomer present, the rate is a function of the 0.6th power of the emulsifer concentration, and the rate of emulsion polymerization is a function of the 0.7th power of the initiator concentration instead of the expected 0.4th power. In this work poly(vinyl alcohol), 88% hydrolyzed with a medium molecular weight (i.e., Du Font s Elvanol 52-22), was used as the only externally added emulsifier. Light-scattering studies indicated that this emulsifier formed no aggregates in the aqueous solution. These latter observations may, however, have been made at room temperature and not at the reaction temperature [1]. The conversion versus time curve was essentially linear up to 80% conversion. 

At C > 5 X 10 M, when interface tension decreases to 13 mN/m, emulsification begins, which hinders the measurements of flow rates in thin capillaries. This region is shown in Fig. 28 by dotted curves. 

Oral administration to rats of DDT in solution in three oils of different chemical composition was found to yield significantly different plasma-concentration time curves (see Table 8.9). Emulsification of the oils with 6 % v/v Tween 80 had different effects on both the rate and extent of absorption and was dependent upon the nature of the oil. The effect of each oil on the total gut transit time of a co-administered "Tc-sulphur colloid was investigated. The time taken for 50 % of the marker to be excreted was determined from faecal recoveries and whole body gamma scintigraphy. The sulphur colloid was most rapidly cleared in the presence of liquid paraffin (r5o . = 9.8 3.6h). There was no significant difference in the total transit times in the presence of Miglyol 812 ( 50% = 15.5 2.0h) and arachis oil (tso% = 14.1 1.1 h). Therefore, the differences in DDT absorption may only be explained in part by the effect of oils on total gut transit time. 

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