Regular Article

Mechanical, dielectric, and physicochemical properties of impregnating resin based on unsaturated polyesterimides^★

¹ Université de Toulouse, UPS, INP, CNRS LAPLACE (Laboratoire Plasma et Conversion d'Energie), Toulouse, France
² CNRS, LAPLACE, 118 route de Narbonne, 31062 Toulouse Cedex 9, France
³ NIDEC Corporation, Bd Marcellin Leroy, 16915 Angoulême Cedex 9, France
⁴ Physique des Polymères, Institut Carnot CIRIMAT, Université Paul Sabatier, Toulouse, France

^* e-mail: fetouhi@laplace.univ-tlse.fr

Received: 5 December 2016
Received in final form: 23 May 2017
Accepted: 7 August 2017
Published online: 6 October 2017

Abstract

This work aims to characterize the dielectric and the mechanical properties of a resin based on an unsaturated polyesterimide diluted in methacrylate reactive diluents used in the impregnation of rotating machines. The broadband dielectric spectrometry and the dynamic mechanical analysis were used to quantify the changes in dielectric and mechanical properties of the network PEI resin, as a function of temperature and frequency. The network characterizations highlight the presence of two main relaxations, α and α′, confirmed by the differential scanning calorimetry analysis, showing the complexity of the chemical composition of this resin. The dielectric spectroscopy shows a significant increase in the dielectric values due to an increase of the material conductivity, while the mechanical spectroscopy shows an important decrease of the polymer rigidity and viscosity expressed by an important decrease in the storage modulus. The PEI resin shows a high reactivity when it is submitted in successive heating ramps, which involves in a post-cross-linking reaction.