Relation between glass transition and melting of PEO-salt complexes

Ionic conductivity and thermal properties on (PEO)(16)LiClO4 complexes mixe d with 29 different inert fillers have been studied. The ionic conductivity at 100 degrees C, where the polymer electrolytes are mostly amorphous, doe s not change markedly, revealing that ceramic particles are almost inert. A t room temperature, the ionic conductivity was more or less enhanced or red uced according to filler species, indicating that the ceramic particles giv e rise to morphological changes, thus modifying the crystallinity and PEO c hain stiffness. We have examined whether any relations exist between variou s quantities such as the conductivity, particle size, glass transition temp erature (T-g), melting temperature (T-m) of PEG, and heat of melting. For 3 0 different species, we found a correlation only between T-g and T-m. Among various factors, the size and morphology of spherulite and nonspherulitic amorphous materials were regarded to be of primary importance on the occurr ence of the correlation. (C) 2000 Elsevier Science Ltd. All rights reserved .