Dielectric properties, measurement

Tinga, W.R., Microwave systems design and dielectric property measurements, Mater. Res. Soc. Bull., 1994, 347,1. 

This Section presents a cross-referenced bibliography on the application of dielectric property measurements to thermosetting materials. Our literature search identified almost 200 papers with some relevance to the subject. Of these, we have selected about 70 for inclusion in this section. These papers provide particularly useful application examples, or provide data typical of the particular material or application which future investigators can use for comparisons with their own results. 

In dielectric property measurements, MAE manifests as a loss minimum and the magnitude of the loss minimum can be as high as 1 order of magnitude. Rather dramatic changes occur in the mixed alkali regions in the internal friction behaviour. Shown in Figure 6.08 is the... 

USA) is used. Suspensions are characterized g by measuring their electrophoretic mobility using Coulter DELSA 440SX and deposition 2 rate. Microstructure of the sintered samples is characterized by SEM and dielectric properties measured as a function of. S temperature using HP impedance meter. i... 

Bircan, C. and S. A. Barringer. 1998. Salt-starch interactions as evidenced by viscosity and dielectric property measurements. Journal of Food Science 63 983-986. 

The automated volume resistivity/dielectric properties measuring system is schematically drawn in Figure 5.2. The whole system is controlled by the HP9000/300 computer which runs either the specific volume resistivity measuring program or the dielectric properties measuring program. 

The role of inherent polarization and ionic transport effects in actuation mechanism of EAPap actuators are investigated. To physically investigate the actuation mechanism, several tests are performed. X-ray diffraction (XRD) spectra are compared before and after electrical activation and the possibility of crystalline structure change is observed. Dielectric property measurement indicates a dependence of the dielectric constant on fiber direction, as well as on frequency, humidity, and temperature. Thus, we conclude that piezoelectric effect and ionic migration effect are in the EAPap at the same time associated with dipole moment of cellulose paper ingredients. The amount of these effects may depend on environmental condition. 

FIGURE 8.45 Dielectric property measurement techniques used for various frequency ranges. 

DIN 53483 Testing of insulting materials Determination of dielectric properties measuring cells for liquids for frequencies up to 100 MHz. 

The purpose of this Chapter is to describe the dielectric properties of liquid crystals, and relate them to the relevant molecular properties. In order to do this, account must be taken of the orientational order of liquid crystal molecules, their number density and any interactions between molecules which influence molecular properties. Dielectric properties measure the response of a charge-free system to an applied electric field, and are a probe of molecular polarizability and dipole moment. Interactions between dipoles are of long range, and cannot be discounted in the molecular interpretation of the dielectric properties of condensed fluids, and so the theories for these properties are more complicated than for magnetic or optical properties. The dielectric behavior of liquid crystals reflects the collective response of mesogens as well as their molecular properties, and there is a coupling between the macroscopic polarization and the molecular response through the internal electric field. Consequently, the molecular description of the dielectric properties of liquid crystals phases requires the specification of the internal electric field in anisotropic media which is difficult. 

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