| Abstract: | Audio-frequency dielectric relaxation measurements and differential scanning calorimetry studies have been performed on poly(ethylene oxide) (PEO) complexed with calcium and barium thiocyanate. The measurements were performed over the temperature range 5.5-300 K. The relaxation spectrum for the complexed material consists of two peaks. The activation enthalpy for the peak corresponding to the γ relaxation of pure PEO depends upon the size of the dopant cation. The activation enthalpy for the second peak is independent of the nature of the dopant cation and is very similar to that observed for the αc relaxation observed in pure PEO. Furthermore, the room-temperature electrical conductivity of the complexed materials is much smaller than that for pure PEO and hence very much less than for PEO-complexed with alkali-metal salts. However, above Tg the conductivity rises rapidly and is larger for the barium-thiocyanate-complexed PEO than for the calcium-complexed material. Finally, the DSC studies show that one effect of the ions is to shift the glass transition to higher temperatures. |
