Dielectric features of two grades of bi‐oriented isotactic polypropylene |
| |
Authors: | Abdelkader Kahouli Olivier Gallot‐Lavallée Pacal Rain Olivier Lesaint Christophe Guillermin Jean‐Marc Lupin |
| |
Affiliation: | 1. Univ. Grenoble Alpes, G2Elab, Grenoble, France;2. CNRS, G2Elab, Grenoble, France;3. Rectiphase, Schneider Electric, Pringy, France |
| |
Abstract: | The dielectric properties of two grades of bi‐oriented isotactic polypropylene were studied with a variety of techniques: breakdown field measurements, dielectric spectroscopy, thermally stimulated depolarization currents (Is), and direct‐current (dc) conduction I values. Standard polypropylene (STPP) and high‐crystallinity polypropylene (HCPP) films were investigated. Measurements were carried out over a wide temperature range (?150°C/+125°C). The breakdown fields in both materials showed a very small difference. On the other hand, the dielectric losses and dc conduction I values were significantly lower in HCPP. Both materials showed a decrease in the dielectric loss versus temperature in the range 20–90°C; this is favorable for application in alternating‐current power capacitors. The analysis of the dc I value allowed us to find evidence of two main conduction mechanisms: (1) below 80°C in both materials, a hopping mechanism due to the motion of electrons occurred in the amorphous phase, and (2) above 80°C, ionic conduction occurred in HCPP, and hopping conduction occurred in STPP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42224. |
| |
Keywords: | applications dielectric properties structure property relations |
|
|