Dielectric features of two grades of bi‐oriented isotactic polypropylene

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 (2150 C/1125 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.

Compounding, Structure and Dielectric Properties of Silica-BOPP Nanocomposite Films

“…3 along with a commercial capacitor BOPP reference from [15]. The measured εr values were generally within the expected range for BOPP [15,16], showing a slightly decreasing trend with increasing temperature from -60 °C to 125 °C. Although small differences in εr were noticed between the studied materials, it is currently challenging to assess the role of silica alone, as such variations could also be attributed to film voids [3] and/or thickness measurement inaccuracy [17].…”

Practical Notes on the Measurement and Interpretation of Thermally Stimulated Discharge Currents in Biaxially Oriented Polypropylene

“…antioxidants), chemical impurities or melting of less perfect PP crystallites [5]- [7]. Previously, the high temperature TSDC peaks of BOPP have also been associated with ionic conduction [8]. As opposed to the shallow trap (α-) TSDC peaks for which the peak location and intensity was always well repeatable, the TSDC (ρ-) peaks associated with space charge were often less predictable, showing considerable variation in TSDC sign, intensity and location even for parallel samples measured under identical conditions.…”

Discharge Characteristics and Plasma Erosion of Various Dielectric Materials in the Dielectric Barrier Discharges

“…The PP is an inexpensive polymer material made of carbon (C) and hydrogen (H) [38][39][40][41] that is used in a variety of fields such as packaging films, fibers, and daily goods. The PP film is prone to oxidation (or degradation) when it is exposed to heat or the ultraviolet light.…”