This study focus on the effect of δ-Al(2)O(3) nanofillers on the dc-conductivity, glass transition, and dielectric relaxations in the polymer electrolyte (PEO)(4):LiClO(4). The results show that there are three dielectric relaxation processes, α, β, and γ, in the systems, although the structural α-relaxation is hidden in the strong conductivity contribution and could therefore not be directly observed. However, by comparing an enhanced dc-conductivity, by approximately 2 orders of magnitude with 4 wt % δ-Al(2)O(3) added, with a decrease in calorimetric glass transition temperature, we are able to conclude that the dc-conductivity is directly coupled to the hidden α-relaxation, even in the presence of nanofillers (at least in the case of δ-Al(2)O(3) nanofillers at concentrations up to 4 wt %). This filler induced speeding up of the segmental polymer dynamics, i.e., the α-relaxation, can be explained by the nonattractive nature of the polymer-filler interactions, which enhance the "free volume" and mobility of polymer segments in the vicinity of filler surfaces.

This study has focused on the ionic conductivity (of impurities) and the changes in relaxation behavior of semicrystalline poly(ethylene oxide) (PEO) around its melting temperature of the crystalline regions. Our main aim was to understand the implications of nucleation and growth of spherulitic structures on the general dynamical properties of the polymer chains and how these dynamical alterations affect the ionic conductivity. Impedance data have been scaled and analyzed under conductivity and modulus formalisms over wide ranges of frequency and temperature. The analysis of the scaled formalisms indicates that both the conductivity and the structural relaxation mechanisms are temperature independent above the melting point of PEO. However, below the melting point, the slow crystallization of PEO leads to growth of spherulites and also to the formation of "interphase" regions. These morphological changes result in a hindered long-range dc conductivity, which, in turn, leads to a decoupling of the dc conductivity and the structural relaxation below the melting point of PEO.

No abstract

No abstract

No abstract