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

Abstract

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 β 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 ρ 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. Copyright © 2004 Society of Chemical Industry

TSDC spectroscopy of relaxational and interfacial phenomena

“…Polymers with imide [338][339][340]343,[345][346][347][348][349][350][351][352]) and amide [351,353] structures (which are of interest from a practical point of view), demonstrate certain regularities in their relaxation phenomena. The much larger polarity and polarisability of C-N and N-H bonds in comparison with C-C and C-H provide the relaxation effects of several mechanisms.…”

Study of relaxations in epoxy polymer by thermally stimulated depolarization current (TSDC) and dielectric relaxation spectroscopy (DRS)

“…The activation energy of the dc conductivity at low temperature (from 51 to 108 • C) does not appear directly in the VTFH equation but has to be calculated from the following relation [2,30,31]:…”

The effects of chemical structure on the dielectric properties of polyetherimide and nanocomposites

“…The dielectric constant for pPEI is slightly higher than that of mPEI. This is caused by the better dielectric behavior associated with pPEI [3]. Correlation between high free volume and low dielectric constant has been previously reported for polyimides [18].…”

“…Although Ultem 1000 has good melt processability and solubility in some solvents, its relatively poor thermal stability limits its application in advanced materials. To improve the thermal properties of Ultem 1000, GE Plastics further introduced Ultem 5000 by substituting mPDA with p-phenylene diamine (pPDA) as one of the monomers [3]. Though the thermal stability improved, it became insoluble in most solvents.…”