Polymers dielectric losses

Polymer Dieleetrie permittivity e, eonventional polymer Dielectric permittivity e, plasma polymer Dielectric loss tangent tan S, eonventional polymer Dielectric loss tangent tan S, plasma polymer... 

Ester-ether segmented polymer Dielectric loss peak and... 

B. Zimm. Dynamics of polymer molecules in dilute solutions viscoelasticity, low birefringence and dielectric loss. J Chem Phys 24 269-278, 1956. 

Typically, large-scale gas filling makes the main characteristics of foam plastics — coefficients of heat and temperature conductivity, dielectric permeability, and the tangent of the dielectric loss angle — totally independent of the chemical structure of the original polymer [1],... 

Zimm, BH, Dynamics of Polymer Molecules in Dilute Solution Viscoelasticity, Flow Birefringence and Dielectric Loss, Journal of Chemical Physics 24, 269, 1956. 

Figure 7. Temperature dependence of dielectric loss of l c polymers. Curves are displaced...

Dielectric Loss. Usually, the dielectric loss of plasma polymerized hydrocarbon is larger than that of the conventional polymer by more than one order of magnitude. This difference is supposed to be caused by the oxidation of the film (J34). For both samples of PPE, a loss peak appeared at -30 °C at the measurement frequency of 1 KHz. The activation energy of this peak was 0.68 eV as shown in Fig. 8 for both samples. This value was almost same as... 

The dissipation factor of capacitors at high frequencies is determined by the series resistance. For low frequencies there may be losses caused by leakage currents as well as by slow components in the polarizability, especially of high e ceramics and polymer dielectrics. The dissipation factor of the SIKO at room temperature is below 10-4. At 200 °C it is still very low (2X10-4). 

This paper discusses the latest advances in manufacturing Community Antenna Television (CATV) cables via the gas injection process. Developments in polymer technology are discussed which have led to the production, by gas injection, of highly expanded, ultra low dielectric loss PE cable insulation for CATV and data transmission 3 refs. 

The electric properties of polymers are also related to their mechanical behavior. The dielectric constant and dielectric loss factor are analogous to the elastic compliance and mechanical loss factor. Electric resistivity is analogous to viscosity. Polar polymers, such as ionomers, possess permanent dipole moments. These polar materials are capable of storing... 

The electrical properties of materials are important for many of the higher technology applications. Measurements can be made using AC and/or DC. The electrical properties are dependent on voltage and frequency. Important electrical properties include dielectric loss, loss factor, dielectric constant, conductivity, relaxation time, induced dipole moment, electrical resistance, power loss, dissipation factor, and electrical breakdown. Electrical properties are related to polymer structure. Most organic polymers are nonconductors, but some are conductors. 

The observation of these dielectric relaxation processes arising from carbonyl features, has also been reported by Tibbit and co-workers in plasma polytetra-fluoroethylene as well as other plama polymers. In measuring the dielectric loss tangents over a frequency range of 10 -10 Hz at temperatures of — 150 to 100 °C, they have demonstrated that the dielectric loss curves of plasma polymers derived from hydrocarbon and fluorocarbon monomers are very similar, but bear no resemblence to their conventionally polymerized counterparts. 

F ure 6.37 Mechanical and dielectric loss tangents for poly (chlorotrillnoroethylene). Reprinted, by permission, from F. Rodrignez, Principles of Polymer Systems, 2nd ed., p. 271. Copyright 1982 by Hemisphere Publishing Corporation. 

Figure 6.44 Dielectric loss factor as a function of cure time and frequency of the oscillating electric field in a fiber-reinforced polymer. Reprinted, by permission, from P. K. Mallick, Fiber-Reinforced Composites, p. 365. Copyright 1988 by Marcel Dekker, Inc.

Two other important electrical properties must be taken into consideration when polymers are used as insulation for a high-voltage power cable or electronic wires. ° These are the dielectric constant and the dielectric loss factor, which characterize the energy dissipation in the insulation, the capacitance, the impedance, and the attenuation. 

We wanted to be able to correct measurements of dielectric loss (conductance) and dielectric constant of polymerizing styrene solutions for whatever contribution arose from the dead polystyrene present in the solutions. What better way to make polystyrene that was free of all catalyst fragments and polar groups than to irradiate pure, dry styrene Using the same exhaustive drying technique that we were developing for our a-methylstyrene studies, we prepared a batch of pure, dry styrene. This was then to be irradiated under such conditions that approximately 15% conversion to polymer would occur. 

Plasticizers include tricresyl phosphate and trixylyl phosphate. Foaming agents can be added in the case of using the polymers for wires, which require low dielectric constant and low dielectric loss tangent, such as communication cables, coaxial cables for computers and high-frequency cables. 

Clark, M.B., Zimm,B.H. A linearized chain model for dielectric loss in polymers. ACS Polymer Preprints 12, 116-120 (1971). See also Tobolsky,A.V., DuPre,D.B. Macromolecular relaxation in the damped torsional oscillator and statistical segment models. Advan. Polymer Sci. 6,103-127 (1969). 

The expressions in brackets are the expansivities above and below Tg. The constant K3 is a function of bond type in chains and is really constant for every class of polymers. The physical interpretation of this equation may be consistent with the iso-free-volume concept. However, we believe that the introduction of this equality is in practise a denial of the concept. There are also other arguments against this concept. Kastner56 found, for example, that dielectric losses diminish during the isothermal volume contraction, which indicates a dependence of relaxation times on free-volume. However, if we assume that relaxation time depends exclusively on free-volume, the calculated reduction factor differs from the experimental one. 

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