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Emulsion dielectric properties

Double emulsions may offer some advantages for food appheations mainly with relation to their eapability to encapsulate (or entrap) in the internal eompartments some water-soluble substances that are flien slowly released. The double emulsion can also be used in the food industry where an external water phase is more aeeeptable in terms of palatability than an oil one (93,94). On this basis several new products have been patented in the form of W/O/W emulsions, as salted creams (encapsulation of salt), aromatic mayonnaise, etc. (95-98). Fiuther food applications are related to the double-emulsion dielectric properties for example one can prepare a W/O/W system having the same volume fraction of the dispersed phase and the same texture as a simple emulsion, but with a lower oil eontent (due to the existence of the aqueous eompartments in the food globules), i.e., low-calorie mayonnaise (93). [Pg.396]

Among the polyesters that are used for PVC, the copolymers of butadiene with ethyl fumarates and ethyl acrylates deserve mention. They have been produced by Badische Anilin-und Sodafabrik (BASF) under the commercial name Palamoll. Palamoll I consists of 75% diethyl fumarate and 25% butadiene Palamoll II contains equal parts of butadiene and ethyl acrylate. In combination with the same amount of liquid plasticizers (such as DOP), films with cold resistance down to — 60°C. can be produced. These products are especially important for cable insulation because of their good dielectric properties. The Palamoll products are produced by emulsion polymerization and can be directly combined with emulsions of PVC. [Pg.99]

The dielectric properties of water have been extensively used to determine moisture content in food systems. However, only veiy recently have we used the complex dielectric properties of emulsions in the microwave frequency region to characterize both emulsion type and water content [50-52], We have developed both a cavity resonance dielectrometer capable of operating at 8-11 GHz and an interference dielectrometer operating at 23.45 GHz. [Pg.18]

Finally, an area which is in need of much further research is that of the dielectric properties of two-phase systems such as frozen foods, emulsions, whips and foams. It is well known that the dielectric behavior of particles of one dielectric property imbedded in a substrate of another, behave very differently from a distributive mixture of both. Fricke (1955) developed a model for randomly oriented oblate spheroids suspended in a continuous medium. It is expected that this model may be used successfully to model two-phase food systems, but to date there is very little literature reporting such studies. [Pg.229]

Ohlsson, T., Enriques, M. and Bengtsson, N. 1974. Dielectric properties of model meat emulsions at 900 and 28 MHz in relation to their composition. Journal of Food Science. 39 1153. [Pg.232]

Erie, U., M. Regier, C. Persch, and H. Schubert. 2000. Dielectric properties of emulsions and suspensions Mixture equations and measurement comparisons. The Journal of Microwave Power and Electromagnetic Energy 35 185-190. [Pg.82]

Recently a new field, mesoscopic physics, has emerged. It is interesting to understand the physical properties of systems that are not as small as a single atom, but small enough that the properties can be dramatically different from those in a larger assembly. All these new mesoscopic phenomena can easily be observed in the dielectric properties of colloid systems. Their properties strictly depend on the dimensional scale and the time scale of observation. Self-assembling systems such as micellar surfactant solutions, micro emulsions, emulsions, aqueous solutions of biopolymers, and cell and lidposome suspensions all to-... [Pg.110]

It is necessary to choose a model that will adequately describe the dielectric properties of the micro-emulsion. Most ofthe existing theories (106,153) operate with a system consisting of well-defined geometrical structures such as spherical or ellipsoidal... [Pg.143]

There is a constant challenge for improved techniques in order to make accurate predictions on the colloidal stability of various sytems. In this section we demonstrate how dielectric spectroscopy can be applied as a technique to follow the breakdown of water-in-oil emulsions and to monitor the sedimentation of particle suspensions. Dielectric spectroscopy, combined with statistical test design and evaluation, seems to be an appropriate technique for the study of these problems. However, one should continue to seek satisfactory theoretical models for the dielectric properties of inhomogeneous systems. [Pg.145]

Theoretical models for the dieleetrie properties of heterogeneous mixtures [for instance, Eq. (20), or extensions of this model] are commonly applied in order to explain or predict the dieleetrie behavior also of emulsions (106, 158). However, in the present theories a homogeneous distribution of the dispersed phase is required. This requirement is rarely fulfilled in a real emulsion system where the inherent instability makes the emulsions go through different stages on the way towards complete phase separation. Proeesses like sedimentation, flocculation, and coalescence continuously alter the state of the system (Fig. 36). These processes also influence the dielectric properties (159—162). Thus, the dielectric properties of one given sample may vary considerably over a period of time (160), depending on the emulsion rate. [Pg.145]

The effect of flocculation on the dielectric properties of disperse systems is well documented, both when it comes to suspensions of solid particles and emulsions. [Pg.145]

Also, Hanai (11) exposed his systems to shear. In order to verify his theory on the dielectric properties of concentrated emulsions (161, 62), dielectric measurement on W/0 emulsions were performed at rest and under influence of shear forces. At rest the static permittivities by far exceeded the values predicted from Eq. (20). However, when modestly high shear forces were applied, Hanai found good... [Pg.146]

An alternative approach is where the aggregates, formed as a result of flocculation, are treated as subsystems of the emulsions (166). The dielectric properties of the subsystems will be decisive for the dielectric properties of the overall system. [Pg.147]

If we treat the free water droplets as one type of particle and the floes as the other type, Eq. (85) may be used to find the dielectric properties of a partially flocculated emulsion. [Pg.148]

Skodvin and SjOblom used dielectric spectroscopy in conjunction with rheology to study a series of emulsions (54). A close cotmection was found between the viscosity and dielectric properties of the emulsions. The large effects of shear on both the static permittivity and the dielectric relaxation time for the emulsion was ascribed, at least in part, to the degree of flocculation in the emulsion system. At high shear rates, at which emulsions are expected to have a low degree of flocculation and high stability, the dielectric properties still varied from those expected from a theoretical model for spherical emulsion droplets. [Pg.414]

M Clausse. Dielectric properties of emulsions and related systems. In P Becher, ed. Encyclopedia of Emulsion technology. Vol 1. New York Marcel Dekker, 1983, p 481. [Pg.489]

Gas hydrate formation is a well-known obstacle in the transport of gas, oil, and water. The formation of such chlatrates and their agglomeration will eventually plug pipes and prevent transport. One way to overcome this problem is to form the gas hydrates in a water-in-oil emulsion. The chapter by Tore Skodvin summarizes some current research at the University of Bergen in this field. It is stated that dielectric spectroscopy is a convenient technique to follow the formation of gas hydrates inside the water droplets, and because of this formation the dielectric properties of water change remarkably. It is also shown that when the gas hydrate particles are emulsified in a water-in-oil matrix one can transport up to about 30 weight% of water without any inhibitors present. [Pg.739]

Sudha and Sivakala [119] investigated the EMI SE and dielectric property of electrically conducting PS/PANI blends prepared through I emulsion polymerization. It was reported that the conductive blends with the low percolation threshold concentration (5wt%) exhibited EMI SE of -1 to lOdB,... [Pg.142]


See other pages where Emulsion dielectric properties is mentioned: [Pg.374]    [Pg.344]    [Pg.365]    [Pg.284]    [Pg.455]    [Pg.381]    [Pg.381]    [Pg.145]    [Pg.146]    [Pg.148]    [Pg.697]    [Pg.3]    [Pg.867]    [Pg.629]    [Pg.202]    [Pg.30]    [Pg.166]    [Pg.123]    [Pg.456]    [Pg.399]    [Pg.226]    [Pg.69]    [Pg.445]    [Pg.149]    [Pg.161]    [Pg.144]    [Pg.213]    [Pg.351]    [Pg.1240]   
See also in sourсe #XX -- [ Pg.229 ]




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