Emulsions mean particle size

Referring to Table 4.8, there are differences between the two homogenizers and types of particle size analysis. However, an independent study (Gooch 2002) showed that emulsification with an APV Homogenizer (3,500 psig) produced an emulsion with a mean particle size of 0.688/1.128 pm (number/volume-weight geometric mean). 

At the optimum HLB the mean particle size of the emulsion is at a minimum (Fig. 7.13) and this factor would explain to a large extent the stability of the system (see equations 7.1 and 7.2, for example). 

The influence of phase volume on the flow properties of an emulsion is shown in Fig. 7.26. In this diagram the relative viscosity of the system increases with increasing 4>, and at any given phase volume increases with decreasing mean particle size, D. These and other factors which affect emulsion viscosity are listed in Table 7.6. 

As most emulsions are polydisperse, the influence of particle size and, in particular, of particle size distribution on viscosity is important. Figure 7.26 shows the viscosity of w/o emulsions varying in mean particle size (D ) stabilised with sorbitan trioleate. 

Figure 10. Left Transmission spectra reported at three different times during of a styrene emulsion polymerization reaction. Right Mean particle size as function of time for the reaction as a function of time.

Figure 5.13 pH-dependence of (a) the droplet charge and (b) mean particle size for a whey protein-stabilized emulsion. Extensive droplet flocculation occurs in protein-stabilized emulsions near the lEP of the adsorbed proteins, because the electrostatic repulsion between the droplets is not large enough to overcome the attractive interactions. 

Mean particle size microm- eter 100-150 (suspension) 40-50 (general purpose emulsion) 2-25 (paste forming) ... 

Figure 28 Change of apparent mean particle size of a cetrimide emulsion measured with a Coulter counter as a function of time. All primary dilutions were made in 0.0003 M cetrimide in normal physiological saline. Secondary dilutions were made in saline containing the following concentrations of cetrimide A—0.00003 M B—0.000015 M C—0.0003 M D—0.00015 M E—0.003 M, F—0.03 M. (Reproduced with permission from Ref. 34.)...

Disperse systems occur in a variety of industrial processes. In many of these processes, the mean particle size, the particle size distribution, and the particle concentration are important criteria for the process flow and the quality of the produced products. In emulsions, particle size and concentration have a significant impact on the stabihty of the emulsion. In spray drying processes, the particle size defines the ratio of surface area to volume of the particles and therefore the expiration of the drying process and the properties of the resulting particles. Also in dedusting and filtration processes, the particle size and concentration have a significant impact. 

A solid microcarrier for encapsulating flavor-enhancing ingredients such as 5 -ribonucleotide was prepared from W/O/W emulsion using cacao butter as a melted lipid phase (Kukizaki et al., 2001). This microcarrier was used in Japan as a supplement in miso paste. The W/O emulsion with a mean particle size of 0.48 tm was produced at 40°C using a rotor-stator homogenizer. This W/O... 

FIG. 13 Effect of the homogenization pressure on mean particle size and viscosity of 30% emulsions containing castor oil and middle chain triglycerides (MCTs), 1 1. (From Ref. 118 with permission from Elsevier Science.)... 

Many different combinations of surfactant and protective coUoid are used in emulsion polymerizations of vinyl acetate as stabilizers. The properties of the emulsion and the polymeric film depend to a large extent on the identity and quantity of the stabilizers. The choice of stabilizer affects the mean and distribution of particle size which affects the rheology and film formation. The stabilizer system also impacts the stabiUty of the emulsion to mechanical shear, temperature change, and compounding. Characteristics of the coalesced resin affected by the stabilizer include tack, smoothness, opacity, water resistance, and film strength (41,42). 

Many observations on the effects of DDT-oil aerosols dispersed from the ground as a means for controlling salt-marsh and anopheline mosquitoes have been summarized by La Mer et al. (50). The effects of particle size meteorological conditions, various emulsions, time of exposure, and the relationship of the habits of various mosquitoes to the use of thermal generators are given. This report discusses experiments of a pioneer nature. 

Small-Volume Parenterals Color, clarity of solutions, particulate matter, pH, sterility, endotoxins. Powders for injection solutions include clarity, color, reconstitution time and water content, pH, sterility, endotoxins/pyrogens, and particulate matter. Suspensions for injection should include additional particle size distribution, redispersability, and rheological properties. Emulsion for injection should include phase separation, viscosity, mean size, and distribution of dispersed globules. 

Figure D3.4.7 Change in cumulative particle size distribution of a 20% (w/v) oil-in-water emulsion stabilized by 2% (w/v) Tween 20 at the lower port (A) and upper port (B). (C) Change in mean droplet diameter and volume fraction of the emulsions as a function of time.

Under suitable conditions a reasonably stable latex may be formed (/). Although many of the factors relating to polymerization rate, molecular weight and particle size in emulsion have been studied [reference (134) is an example] the literature on homopolymers is by no means as extensive as that pertaining to copolymers. Attempts to prepare bead homopolymers have not been very successful. 

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