AC conductivity and dielectric constant studies of vinyl chloride:vinyl acetate copolymers

AC conductivity σ(ω)_m and the dielectric constant ε´ of vinyl chloride:vinyl acetate (VC;VAc) copolymers having 3, 10 and 17% VAc content (by weight) have been measured in the temperature range 77-410 K and in the frequency range 50 Hz-100 kHz. At temperatures up to 250 K, the AC conductivity can be expressed as σ(ω)=Aω^s, where the slope, s , is close to unity and decreases with the increase in temperature. The dielectric constant in this temperature region shows a very weak frequency and temperature dependence. At temperatures above 300 K, the AC conductivity shows a strong temperature dependence. However, the dielectric constant in this temperature region shows a strong frequency dispersion. The mechanisms of conduction in low- and high-temperature regions are discussed in the light of an existing theoretical model