Dielectric Relaxation Behaviour and AC Conductivity of Vinylpropionate and Ethylmethacrylate (VP-EMA) copolymers

A systematic measurement of dielectric constant (ε) and dielectric loss (tanδ) on powder pressed pellets of VP-EMA copolymer in composition 50/50 have been carried out in the frequency range 200Hz -100kHz and in the temperature range from room temperature to 180°C, covering through the glass transition T_g. Two sets of relaxation peaks on slight above room temperature and the other slightly above T_g are noticed from tanδ versus temperature curves for different frequencies. The peaks are attributed to β and α-relaxations. Temperature coefficient of dielectric constant (TCε) is evaluated to understand the nature of the temperature dependence. AC conductivity is evaluated to understand the conduction process. Activation energy is calculated from loss (tanδ) versus temperature curves and logω_p versus reciprocal temperature curves. Activation energy is also calculated from Arrehenius plots.