The high electric field behavior in PEN

The polymers today find an important place in electrical engineering. In particular, the PEN (Polyethylene-2,6-Naphthalene Dicarboxylate) an aromatic polyester belonging to the group of thermoplastics is getting an important place in several applications in the electronic and electric industries thanks to their excellent mechanical, thermal resistance, dielectric and insulating characteristics. For this reason, the study of each characteristic is growing. Thus, in the field of electrical engineering, the investigation is mainly directed to obtain a vision, more clear, of charge injection and carrier migration during low and high fields which constitutes an essential factor in the future of these materials. We have studied the PEN samples under a large range of low and high dc electric fields (12-300 kVmm^-1). Measurements of transient currents and the isochronal characteristics of I(F) have shown the role played by thickness and morphology to characterize its electrical properties. No influence of thickness at low electric fields has found in relation to the current produced; on the contrary, we have found a great influence at high fields. In addition, we have detected an influence of morphology (amorphous and semicrystalline). At low electric fields, the current density in amorphous samples is more important than in semicrystalline samples (hereafter called here SC); at high fields, this effect is more pronounced, meaning that carrier migration processes is related to the morphology.