Amorphous Phase Separation, Salt Precipitation, and High Pressure Effects in PPO (Poly) propylene oxide)) Containing NaI

摘要

Audio frequency dielectric constant and electrical conductivity, Sodium 23 NMR, and differential scanning calorimetry studies have been carried out on poly(propylene oxide) (PAREL elastomer) containing various concentrations of Sodium iodide. Both the NMR and the electrical conductivity measurements were performed at high pressures. The low temperature DSC results show the existence of two amorphous phases, one very dilute and one with a concentration of approximately 8 monomer units per sodium. All techniques applied indicate that the more concentrated phase is the ion conducting phase. At high temperatures, however, the conductivity decreases as temperature increases. The decrease coincides with an endotherm in the DSC studies which is associated with salt precipitation. The DSC studies show that the salt precipitation temperature decreases as the concentration increases. An explanation for the salt precipitation phenomenon is suggested in that it is found that the dielectric constant of the host polymer decreases as temperature increases. The NMR measurements reveal the presence of both bound and mobile sodium species, where the bound phase probably corresponds to small salt clusters. All high pressure results suggest an increase in the glass transition temperature with applied pressure. (aw)