Abstract:

This article focused on the relationship between the processing parameters of biaxially oriented polypropylene （BOPP） capacitor films and breakdown field strength， as well as the microstructure affecting breakdown field strength. The results indicated that the microstructure affecting breakdown field strength included the crystallinity， mobility of molecular chains in the amorphous region， and roughness of BOPP capacitor films. The higher crystallinity， the more serious was the mobility of molecular chains in the amorphous region limited， the smaller was the roughness， and the higher was the breakdown field strength. During the processing， the molecular chain motion ability in the amorphous region and roughness could be reduced through appropriately reducing the longitudinal stretching temperature. In addition， the crystallinity of BOPP capacitor films increased with an increase in the transverse stretching temperature， thus reaching the goal of improving the breakdown field strength. The establishment of the relationship between the processing， structure and performance of BOPP capacitive films provides a fundamental basis for improving their breakdown field strength in production lines.

Key words: biaxially oriented polypropylene, capacitor film, breakdown field strength, crystallinity, amorphous region