Dielectric dissipation

Material Refractive T ransp arency, Haze, % Dielectric Dissipation Dielectric Volume... 

Some of the other critical properties defined by the industry include volume resistivity, dielectric dissipation factor, insulative resistance and the like. 

IEC 60250, Recommended methods for the determination of the permittivity and dielectric dissipation factor of electrical insulating materials at power, audio and radio frequencies including metre wavelengths, 1969. 

There have been isolated QSPR studies of a number of other polymer properties. These include the dielectric constant [144], the dielectric dissipation factor (tan 8) [168], the solubility parameter [169], the molar thermal decomposition function [170], the vitrification temperature of polyarylene oxides [171], and quantities relating to molecularly imprinted polymers [172, 173]. The interested reader is referred to the literature for further information. 

Yu X, Yi B, Liu F et al. (2008) Prediction of the dielectric dissipation factor tan delta of polymers with an ANN model based on DFT calculation. React Fund Polym 68 1557-1562... 

In the low-temperature part of the /3 transition, the MGI units lead to an increase of mechanical dissipation, whatever the MGI content. In contrast, except for MGIM76 copolymers, one observes for all the other MGIMx a decrease of the dielectric dissipation. In both cases, the effect develops when increasing the MGI content, but passes through a maximum for either MGIM58 in mechanics or MGIM36 in dielectrics. The lowest effect in mechanics, even an opposite effect in dielectrics, are obtained for the MGI-richest copolymer, MGIM76. 

In the high-temperature part, opposite effects are observed in mechanics and dielectrics, except for MGIM76. Indeed, the decrease of mechanical dissipation (relatively to the MMA content response) increases with increasing temperature, but it is the opposite with dielectric dissipation. For MGIM76, in both experiments, the dissipation is larger than expected from the MMA content. 

The dielectric Q factor is the reciprocal of the dielectric dissipation factor tan S (see Section 2.7.2). 

Figure 18.18 Map of dielectric properties of engineering plastics. Among engineering plastics, SPS (impact modified and GF-reinforced HB and IR grades) has very low dielectric dissipation factor and dielectric constant following those of fluorocarbon polymers. PSF, polysulfone PPE, poly(phenylene ether) PES, poly(ether sulfone) PAr, polyarylate...

The viscosity of a sample reflects its ability to absorb microwave energy because it affects molecular rotation. The effect of viscosity is best illustrated by considering ice water. When water is frozen, the water molecules become locked in a crystal lattice. This greatly restricts molecular mobility and makes it difficult for the molecules to align with the microwave field. Thus, the dielectric dissipation factor of ice is low (2.7 X 10 at 2450 MHz). When the temperature of the water is increased to 27°C, the viscosity decreases and the dissipation factor rises to a much higher value (12.2). 

Table 9.4. Measurement frequency v in Hertz, dielectric dissipation factor tan 8 and dielectric constant e observed at room temperature at the specified frequency of measurement, and the fitted value of tan 8 calculated as described in the text, for 206 data points covering a wide variety of polymers. Most measurements were made on commercial samples containing various plasticizers, fillers and other additives, so that the (exp) values listed for many polar polymers differ significantly from (i.e., exceed) the more "intrinsic" e(exp) values listed in Table 9.1. 

Dielectric Loss Tangent - See Dielectric Dissipation Factor. 

IEC60247 Measurements of relative permittivity, dielectric dissipation. Eactor and DC... 

The power loss depends on the phase difference between the alternating current produced by an applied alternating voltage. When the material behaves as a perfect dielectric, the phase difference between the alternating potential and the amplitude of the current is 90° and the power loss is zero. If current and voltage are in phase, then all of the electrical energy is converted into heat and the power output is zero. The ratio of power loss Nv to power output Nb is called the dielectric dissipation factor, tan 6 ... 

Recommended Methods for the Determination of the Permittivity emd Dielectric Dissipation Factor of Electrical Insulating Materials at Power, Audio, and Radio Frequencies... 

Dose Retained tensile Retained elongation Dielectric strength Dielectric Dissipation... 

The major use of CE resins is in the electronic industry, including printed wiring circuit boards, thin cards, multichip module laminates and ship encapsulants. CE resins have replaced epoxy and bismaleimide resins to a great extent for such microelectronic application due to their comparatively lower moisture absorption and dielectric dissipation factor. 

---