Electrical Relaxation in Pure and Alkali Metal-Thiocyanate Complexed Poly(Ethylene Oxide).

Audio frequency complex admittance and DSC studies have been performed on pure polyethylene oxide PEO and PEO complexed with alkali metal thiocyanates over the temperature range 5.5-380K. The dielectric constant of the complexed materials is found to be greater than for pure PEO. A discontinuity in the conductivity is found which increases in temperature as the size of the cation increases. In every case, the discontinuity is associated with a feature in the DSC results. Next, some evidence is given that water may enhance the formation of amorphous complexed PEO. In pure PEO, alpha sub a and gamma relaxations are observed in good agreement with previous work. A thermal anomaly is found corresponding to alpha sub a . In addition, alpha sub c is identified in pure PEO. Very little difference is found for the gamma relaxation between pure PEO and PEO-LiSCN and PEO-NaSCN. For PEO-KSCN, three distinct peaks are found in the gamma relaxation region. These results are consistent with a tgt infinity tg-t transition interpretation for gamma where the cations reside within the helical channels at low temperatures. Author