Dielectric and Molecular Structure Characteristics of Biaxial Polypropylene under DC/AC Mixed Voltage

To investigate the dielectric properties and molecular structural properties of biaxially oriented polypropylene (BOPP) films under DC/AC mixed voltages, compare the differences between domestic and foreign BOPP films, and promote the localization process of BOPP, this article selects five types of BOPP films from both domestic and foreign countries for dielectric testing and infrared spectroscopy testing. The test results show that the relative permittivity of all samples remains basically unchanged with the increase of DC voltage; the dissipation factor increases in the low frequency range of voltage and decreases in the high frequency range. Under high DC voltage, the dissipation factor of BOPP can be attributed to additives and impurities during the production process. At any DC/AC mixed voltage, the infrared spectra of all BOPP films doesn't change significantly, indicating that the chemical structure of polypropylene molecules has strong stability.