Study of dielectric properties of thin plastic films

Measures the dielectric properties of thin plastic films by using wound capacitors with different structures under different test conditions after different conditioning. The authors also measured the volume resistivities and water absorptions of these films. After comparison and analysis, it was found that a convenient and precise method to measure dissipation factor and permittivity of thin plastic films is to test the wound capacitors after treating them at a temperature of 50°C in the pressed state for about 1 hour. In this way, the aluminum foil and the film can contact each other tightly. It was also found that there is a relation between volume resistivity and water absorption. In the case of conditioning and testing at high relative humidity, volume resistivity drops apparently. At low relative humidity, volume resistivity changes little. It is accurate enough to measure volume resistivities of film at a temperature of about 23°C and a relative humidity of about 50%