Dielectric Relaxation, Electric Conductivity and Thermodynamic Studies on Epoxy Polyurethane Blend and Their Composites

Abstract

The purpose of this study is to improve the dielectric properties of epoxy-based polymer composites by adding rock and glass wool to achieve a relatively high dielectric constant and lower dispersion; hence the dielectric relaxation of composite materials which combines of epoxy/polyurethane reinforced with fibrous materials (rock wool (RW) and glass wool (GW)) with constant weight fraction of (10%) were investigated. The data of AC conductivity have been analyzed in the light of different theoretical models based on correlated barrier hopping (CBH) and Maxwell-Wagner model. The dielectric measurements were carried out for all samples over the frequency range of (10 2 -10 7 ) Hz and over temperature range of (293-463) K 0 . It is found that all samples displayed dielectric dispersion, thus the result for dielectric constant and dissipation factor give a direct evidence of the existence of Debye relaxation leaving a wide distribution of relaxation time. Eyring's relaxation rate equation have been used to determine the thermodynamic parameters, Gibbs free energy of activations and enthalpy for all samples. The results showed the existence of a stronger intermolecular interaction in all samples.