Dielectric relaxation spectroscopic measurements on a novel electroactive polyimide

AC electrical behavior of a novel aromatic electro-optic polyimide was investigated in the temperature range 25 degrees C to 300 degrees C and a frequency range from 1 Hz to 10(6) Hz. Three electrical quantities. impedance, permittivity and electric modulus are reported. The dependence of imaginary and red components of these quantities on temperature and frequency are discussed. The experimental results show that the polymer has high thermal stability below 200 degrees C, where the resistivity, dielectric constant and permittivity are nearly temperature-independent indicating highly rigid structure. Above this temperature, however, a well-defined broad peak corresponding to a relaxation process was observed for which the activation energy was calculated to be 8.5 Kcal/mole. This relaxation is associated with a restricted local rotational motion of the side chain chromophore.