A relaxational and conductive study on two poly(ether imide)s

A study of the relaxations and the conductivity of poly(ether imide) (PEI) ULTEM 5000 was carried out. The results were compared with the ones obtained in a previous study of PEI ULTEM 1000. The glass transition temperature was determined by differential scanning calorimetry (DSC). Then, the relaxations of PEI ULTEM 5000 using the thermally stimulated depolarization current technique (TSDC) on conventionally polarized electrets were studied. Owing to the interesting structure indicated by this technique a more detailed analysis of the beta relaxation was done using window polarization (WP). It was possible to isolate 7 subrelaxations that we related to their counterparts in PEI ULTEM 1000. WP was also used to compare, one by one, the other relaxations that both materials present. The analysis of the rho relaxation showed that the space trapping capability is stronger in PEI ULTEM 5000. The role of conductivity was analyzed using open circuit polarized samples and, more quantitatively, using dielectric analysis (DEA) and the dielectric modulus formalism. DEA and dynamic mechanical thermal analysis (DMTA) were also used to obtain information about the polar relaxations, complementary to that obtained by TSDC. (C) 2004 Society of Chemical Industry.