Studies of Dielectric Relaxation in Solid Polymers and Composites

摘要: Non-linear characteristics of homogeneous solid polymers and polymer-based composites have been studied both experimentally theoretically. In particular experimental studies non-linear dielectric response six polymeric materials the influence composition on properties with high permittivities carried out a theoretical study dipole-dipole interaction in solids based formulation due to P. Debye W. Ramm has made. Time-domain measurements relaxation analysed using stretched exponential function exp[-(t/.tau.). .beta. ] describe dipole component. The parameter b was found vary from about 0.2 at low temperatures unity for higher temperatures. lower value indicates strong correlation between relaxing dipoles while .BETA. = 1 is characteristic independently dipoles. Frequency domain epoxy matrices loaded barium titanate without carbon black as well coated or copper fibres were also out. Due interfacial polarization, real imaginary parts permittivity, Re(e*) Im(e*), far than those matrix itself. case epoxy-barium system addition 4.5 vol% resulted great increase Im(e*). Higher concentrations had effect short-circuiting polarization. epoxy-carbon fibre epoxy-copper systems insulating prior mixing matrix, thus drastically reducing direct electrical contact fibres. resistivities remained high. concept spectrum times investigated context under an external field. particular, embodied their rate equation detail. It that contrast assumptions no complete set eigenfunctions lack self-adjointness. fact solutions proposed by can be shown not satisfy equation. Good approximate obtained Fourier integral operators. Numerical analysis showed they are unphysical, is, lead results contrary facts. This original does give physically correct description nature. However, spite some attempts "repair" unsuccessful yet. main conclusion drawn this work there wide gaps our knowledge composites. Further, still much room experience "Fingerspitzengefuhl" designing developing specialized