Relaxation emulsions

Fig. XIV-2. Dielectric relaxation spectrum of a water-in-oil emulsion containing water in triglyceride with a salt concentration of 5 wt % at a temperamre of 25°C. The squares are experimental points and the lines are fits to Eq. XIV-4. (From Ref. 9.)...

Elastomeric Fibers. Elastomeric fibers are polyurethanes combiaed with other nonelastic fibers to produce fabrics with controlled elasticity (see Fibers, elastomeric). Processing chemicals must be carefully selected to protect all fibers present ia the blend. Prior to scouriag, the fabrics are normally steamed to relax uneven tensions placed on the fibers duriag weaving. Scouriag, which is used to remove lubricants and siting, is normally conducted with aqueous solutions of synthetic detergents and tetrasodium pyrophosphate, with aqueous emulsions of perchloroethylene or with mineral spidts and sodium pyrophosphate. 

For effective demulsification of a water-in-oil emulsion, both shear viscosity as well as dynamic tension gradient of the water-oil interface have to be lowered. The interfacial dilational modulus data indicate that the interfacial relaxation process occurs faster with an effective demulsifier. The electron spin resonance with labeled demulsifiers suggests that demulsifiers form clusters in the bulk oil. The unclustering and rearrangement of the demulsifier at the interface may affect the interfacial relaxation process. 

Power law relaxation is no guarantee for a gel point. It should be noted that, besides materials near LST, there exist materials which show the very simple power law relaxation behavior over quite extended time windows. Such behavior has been termed self-similar or scale invariant since it is the same at any time scale of observation (within the given time window). Self-similar relaxation has been associated with self-similar structures on the molecular and super-molecular level and, for suspensions and emulsions, on particulate level. Such self-similar relaxation is only found over a finite range of relaxation times, i.e. between a lower and an upper cut-off, and 2U. The exponent may adopt negative or positive values, however, with different consequences and... 

Finally, NMR relaxometry has also been used in the determination of composition of meat and meat products. Correlations between relaxation parameters and fat content in minced meat and meat emulsions,115 117 protein content in fresh meat115,118 and moisture content in sausages119 have been demonstrated results from fat determinations are summarised in Table 3. 

A) Elaboration of PLLA-based superparamagnetic nanoparticles Characterization, magnetic behavior study and in vitro relaxivity evaluation Abstract. Oleic acid-coated magnetite has been encapsulated in biocompatible magnetic nanoparticles (MNP) by a simple emulsion evaporation method. 

C.S. Lai, S. Stair, H. Miziorko, J.S. Hyde, Effect of oxygen and the spin label TEMPO-Laurate on F and proton relaxation rates of the perfluorochemical blood substitute FC-43 emulsion, J. Magn. Reson. 57 (1984) 447-452. 

Anklam et al. [91] have attempted to measure the extensional rheological properties of w/o emulsions and HIPEs, using a nozzle-type viscometer. However, the results showed a dependence on the nozzle size used, and long relaxation times. Experiments on other non-Newtonian fluids indicated that it was not possible to obtain reliable results with this kind of instrument. 

In accord with experiments on emulsions (Husband et al., 1997), the molecular configurations deduced from SCF calculations have demonstrated the crucial role of the cluster ( blob ) of 5 charged phosphoserine residues in p-casein in maintaining the steric stabilizing layer, whilst also preventing interfacial precipitation (multilayers). The mobility of this blob was demonstrated experimentally by P NMR measurements on P-casein-stabilized emulsions (ter Beek et al., 1996). It was inferred that, when the effective charge on the blob is reduced (by dephosphorylation) or screened (by salt addition), the macromolecular spring relaxes... 

The widespread applicability of di-O-methylisosorbide as a medium for chemical reactions or as a solvent for pharmaceutical formulations is well documented. In some cases, an additive synergism of the solvent and the solute was observed. Some typical examples mentioned include that it acts as a solvent for muscle-relaxant drugs, which are otherwise difficultly soluble,226 and is used for topical and other types of pharmaceutical formulations,227,228 transdermal controlled-release films229 and tapes,230 anthelmintic solutions,231 antimycotic emulsions,232 and for the treatment of skin disorders, such as eczema.233... 

When a relaxation timeTi for oil/water emulsion is known, the volume fraction of each component phase (Water) for the emulsion can be calculated using an equation... 

Figure 2. Pulse sequence diagram of a Hahn spin-echo experiment with field gradient pulses. Rf- and field gradient pulses are denoted by 90°, 180° and FGP, respectively. The FGP pulses have a length 5 and are separated by an interval A as in the spin-echo sequence given in Fig. 1. VD is a time delay which may be variable in which case also A is variable. A PFG NMR experiment may also be performed with variable 5 or gradient strength (G) and fixed A. Normally, 6 is chosen between 0 and 10 ms and A between 0 and 400 ms. The time delay t depends on the T1 relaxation time of the pure oil of the emulsion but is normally between 130 and 180 ms.

Figure 6. Stress relaxation comparison of two emulsion polymers having the same overall composition. The power feed example utilized a feed profile with increasing butyl acrylate (0-> 0.65), decreasing methyl methacrylate (1.0 -> 0.35), and x = 1.3. The time axis has been shifted to a reference temperature of 26°C.

H T2 relaxation experiments have moreover been used to investigate the phase composition, interfaces and phase diagrams of polymer solutions, emulsions and coreshell lattices [167-173]. 

The best evidence so far for the glassy nature of HDA was provided (1) by measurements of the dielectric relaxation time under pressure at 140 K [206, 251], (2) by the direct vitrification of a pressurized liquid water emulsion to HDA [252], and (3) by a high-pressure study of the glass >liquid transition using differential thermal analysis (DTA) [253], We note here that these studies probe structurally relaxed HDA (eHDA) rather than unrelaxed HDA. It is possible that structurally relaxed HDA behaves glass like, whereas structurally uHDA shows a distinct behavior. Thus, more studies are needed in the future, which directly compare structurally relaxed and unrelaxed HDA. 

Abstract. Surface pressure/area isotherms of monolayers of micro- and nanoparticles at fluid/liquid interfaces can be used to obtain information about particle properties (dimensions, interfacial contact angles), the structure of interfacial particle layers, interparticle interactions as well as relaxation processes within layers. Such information is important for understanding the stabilisation/destabilisation effects of particles for emulsions and foams. For a correct description of II-A isotherms of nanoparticle monolayers, the significant differences in particle size and solvent molecule size should be taken into account. The corresponding equations are derived by using the thermodynamic model of a two-dimensional solution. The equations not only provide satisfactory agreement with experimental data for the surface pressure of monolayers in a wide range of particle sizes from 75 pm to 7.5 nm, but also predict the areas per particle and per solvent molecule close to the experimental values. Similar equations can also be applied to protein molecule monolayers at liquid interfaces. 

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