Investigation of Crystallinity of BOPP Film by Various Techniques Used in High Energy Density Capacitor

Biaxially oriented polypropylene films (BOPP) are commonly used in high energy density capacitor (HEDC). Polypropylene films when stretched in longitudinal and transverse direction offer orderly stacks of folded chains (Lamella) which contribute to enhance the crystallinity of the polymer. The increase in crystallinity of BOPP results in increase in dielectric strength which is responsible for improving the charge density of the polymer. The crystalline nature in the polymer plays an important role for their application in high energy density capacitors. The biaxially oriented film enhances its thermal, mechanical, and electrical properties such as melting point, crystallization temperature, heat of fusion, density, tensile strength, and dielectric strength. The change in crystallinity in the BOPP film can be calculated by using various techniques. In this paper, crystallinity of BOPP film studied by techniques such as differential scanning calorimetry (DSC), X-ray diffraction (XRD), density, and Fourier transform infrared (FTIR) spectroscopy are discussed in detail.