AC conductivity and broadband dielectric spectroscopy of a poly(vinyl chloride)/poly(ethyl methacrylate) polymer blend

Abstract

Alternating-current (ac) conductivity and dielectric relaxation behaviour of a poly(vinyl chloride)/poly(ethyl methacrylate) polymer blend have been investigated intensively in a frequency range from $1 \times 10^{-1}$ to $2 \times 10^{7}$ Hz through a temperature range from 300 to 393 K. The variation of $\sigma _{\mathrm{ac}}$ of pure and polyblend samples showed a plateau region at high temperature and low frequency and this plateau region is decreased with decreasing temperature. Values of the exponent n are less than unity indicative of the correlated barrier hopping for conduction. The values of the exponent n are used to calculate the binding energy ($W_{\mathrm{m}})$ of the charge carriers. The investigation of the frequency dependence of $\varepsilon ^{\prime }$ for pure and polyblend samples showed a dielectric dispersion. The high values of dielectric constant at a low frequency and high temperature are attributed to the effects of space charge due to the electrode polarization. The complex electric modulus (M*) of pure and polyblend samples has been investigated. It is found that the real part of the complex electric modulus, $M^{\prime }$ is increased non-linearly as the frequency increased and reached the steady state at higher frequencies for all samples. On the other hand, the imaginary part of the complex electric modulus, $M^{\prime \prime }$ is characterized by a relaxation peak. The different modes of relaxation, such as interfacial polarization and dipolar relaxation, are detected in low and high frequency regions in the variation plot of $M^{\prime \prime }$ against frequency. The activation energy values of both interfacial polarization and $\upalpha$-relaxation are calculated.