Dielectric relaxation behaviour and ac conductivity of acrylonitrile and Vinyl propionate (an-vp) copolymers

Acrylonitrile based copolymers have a variety of industrial applications and attracted the attention of material researchers with increasing interest in recent years to study their electrical properties with respect to their homopolymers. The dielectric relaxation studies as a function of temperature and frequency of the applied field reveals the information about the nature of segmental motion in polymer chain. A systematic measurement of dielectric constant (e) and dielectric loss (tanδ) on powder pressed pellets of AN VP 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 o C, covering through the glass transition temperature Tg. 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 (TCe) 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.