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

摘要

Alternating-current (ac) conductivity and dielectric relaxation behaviour of a poly(vinyl chloride)/poIy(ethyl methacrylate) polymer blend have been investigated intensively in a frequency range from 1 × 10~(-1) to 2 × 10~7 Hz through a temperature range from 300 to 393 K. The variation of σ_(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_m) of the charge carriers. The investigation of the frequency dependence of s' 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' 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" 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" against frequency. The activation energy values of both interfacial polarization and a-relaxation are calculated.