Characterization of polybenzimidazole (PBI) film at high temperatures

摘要

Polybenzimidazole, a linear thermoplastic polymer with excellent thermal stability and strength retention over a wide range of temperatures, was evaluated for its potential use as the main dielectric in high-temperature capacitors. The film was characterized in terms of its dielectric properties in a frequency range of 50 Hz to 100 kHz. These properties, which included the dielectric constant and dielectric loss, were also obtained in a temperature range from 20 degrees C to 300 degrees C with an electrical stress of 60 Hz, 50 V/mil. The AC and DC breakdown voltages of silicone oil-impregnated films as a function of temperature were also determined. The results obtained indicate that, while the film remained relatively stable up to 200 degrees C, it exhibited an increase in its dielectric properties as the temperature was raised to 300 degrees C. It was also found that conditioning of the film by heat treatment at 60 degrees C for 6 h tends to improve its dielectric and breakdown properties.