The Study of the Molecular Movements in the Range of Glass Transition by the Final Thermally Stimulated Discharge Current Technique

Citation:
Neagu, E. R., C. J. Dias, M. C. Lanca, R. Igreja, P. Inacio, J. N. Marat-Mendes, and Ieee, "The Study of the Molecular Movements in the Range of Glass Transition by the Final Thermally Stimulated Discharge Current Technique", Proceedings of the 2010 Ieee International Conference on Solid Dielectrics, 2010.

Abstract:

The electrical methods used to study the molecular movements are based on the movement of the dipoles under DC or AC electric field. We have proposed recently a combined measuring protocol to analyze charge injection/extraction, transport, trapping and de-trapping in polar or non-polar dielectric materials. The method is used here to analyze the molecular movements in polyimide in the temperature range from 293 to 572 K. A strong relaxation was observed around 402 K and a very weak relaxation around 345 K. This is the beta relaxation which is quite complex. As concern the behavior at high temperatures, above the beta relaxation, a high peak was observed that shifts continuously to higher temperatures as the charging temperature and/or the charging field increase. The maximum current of the peak increases and the temperature corresponding to the maximum current increases as the charging temperature and/or the charging field increase, given a direct observation of the so called cross-over effect related to current decay for sample charged at high fields and/or high temperatures.

Notes:

Neagu, E. R. Dias, C. J. Lanca, M. C. Igreja, R. Inacio, P. Marat-Mendes, J. N. ICSD 2010 International Conference on Solid Dielectrics ICSD JUL 04-09, 2010 Potsdam, GERMANY

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