Measurement of the Crystallinity for PET Films by Complex Dielectric Constant Method

Abstract

The crystallinity of polymer films is very important factor for research as well as manufacture. Several techniques such as X-ray diffraction, density and DSC are used for measuring it. But these methods need much time and labor. A new method for measuring the crystallinity of PET films more easily and quickly by using complex dielectric constants measured by a microwave cavity resonator at 4 GHz has been developed. We obtained good correlation between the density method and the new method by complex dielectric constants for biaxially stretched PET films as well as unstretched PET films.