Epoxy Casting Systems with Harmless Hardeners for Outdoor Applications

Presented thesis is focused on studying of electro-insulating casting systems based on epoxy resin. The aim of the article is to acquaint the reader with the development of this systems – epoxy resin with hardeners that comply with REACH authorization. The temperature and frequency dependence of complex permittivity, complex electric modulus, loss factor and inner and surface resistivity of the given samples are investigated.

Electric Properties of AlGaN/GaN/Si High Electron Mobility Transistors

This work investigated the electrical properties in AlGaN/GaN/Si HEMTsgrown by molecular beam epitaxy. The electrical behavior have been investigated using by electric permittivity, modulus formalism and conductance measurements. As has been found from electrical conductance, dispersive behavior is related to barrier inhomogeneity and deep trap in barrier layer. On the other hand, the strain relaxation of charge transport is studied both permittivity and electric modulus formalisms.

Hopping Conductivity and Dielectric Relaxations in Ag/PAN Nanocomposites

The dependence of the conductivity and electric modulus of silver/polyacrylonitrile nanocomposites on the frequency of an alternating electric field has been studied at different temperatures and starting mixture AgNO3 contents. The frequency dependences on the conductivity of the nanocomposites in the range of 103–106 Hz are in good agreement with the power law f0.8. The observed relaxation maxima in the relation of the imaginary part of the electric modulus on the frequency can be explained by interfacial polarization. It was shown that the frequency dispersions of conductivity and electric modulus were well described by the Dyre and Cole-Davidson models, respectively. Using these models, we have estimated the relaxation times and the activation energies of these structures. A mechanism of charge transport responsible for the conductivity of nanocomposites is proposed. An assumption is made regarding the presence of Ag42+ and Ag82+ silver clusters in the polymer.