Dielectric relaxation studies of poly(N-vinylcarbazole) and poly(3-chloro-N-vinylcarbazole) including the effects of sorbed oxygen

The dielectric relaxation spectrum of poly(N-vinylcarbazole) (PVK) and poly(3-chloro-N-vinylcarbazole) (CLPVK) have been investigated in the temperature range −180–+240 °C. Four relaxations are observed in PVK. The α relaxation (225 °C) is associated with the glass transition of the polymer. On the basis of oxygen-sorption experiments, the γ relaxation (∼−60 °C) has been associated with a rotational libration of the pendant carbazole group. It is also speculated on the basis of this work that an off-axis dipole is induced in the carbazole moiety by the sorbed O2 producing the dielectrically active motion about the symmetry axis of the carbazole moiety. The β (∼80 °C) and the δ (∼−160 °C) relaxations are assigned as carbazole wagging motions and localized backbone motions, respectively. These assignments are based on comparative work in the literature.