THE PHASE-DIAGRAM FOR THE SYSTEM PB(CF3SO3)2-PEO

The phase diagram for the Pb(CF3SO3)2PEOn system, for n = 2 to 100, has been determined using X-ray diffraction and DSC. Intermediate crystalline complexes have been found for n = 5 and 7. Pb(CF3SO3)2PEO7 has a congruent melting point at 138-degrees-C, while a peritectic point is proposed at 220-degrees-C for n = 5 and a eutectic point at 123-degrees-C for about n = 6.5, A ''crystallinity gap'' is found for n = 9-11. It is therefore not possible to establish whether a eutectic composition is formed with PEO in this concentration range, but it is assumed to occur at about n = 10. Crystalline PEO is detected for n greater-than-or-equal-to 12. Measured values of T(g) indicate clearly the reduction in chain mobility resulting from the increased number of crosslinks as the salt concentration increases.