Relaxation of space charge in polyetherimide by dynamic electrical analysis and thermally stimulated depolarization currents

Polyetherimide (PEI) is an amorphous thermoplastic resin with a high glass transition temperature and advantageous mechanical and electrical properties for industrial applications. A previous study by dynamic electric analysis (DEA) shows that the loss factor of PEI increases sharply for temperatures above the glass transition temperature. This increase is associated to its conductive properties by means of a space charge relaxation mechanism. In the case of thermally stimulated depolarization currents (TSDC) measurements, the relaxation of space charge in this material is revealed by the peak ρ, which appears at temperatures above those that correspond to the glass transition peak, α. The aim of this paper is to study the space charge relaxation mechanisms in these polyetherimides by the correlation of the results obtained by TSDC and DEA measurements. In the case of the TSDC measurements, the results will be explained by the general order kinetics model. The Coelho´s model will be used to explain the relaxation of space charge in DEA measurements