Evaluation of Surface Energy for CPP Film Using the Lifshitz-van der Waals/ Acide-Base Method

Corona-modified cast polypropylene (CPP) is widely used in the packaging industry. The corona- treatment side is made of a homopolymer and the unmodified side is made of a random copolymer. One of the most important characteristics of materials used in packaging industries is printability, which is related to surface energy and wettability. For this reason, various theories have been expressed to obtain the surface energy of solid materials. Today, one of the conventional methods for measuring the surface energy of polymers is the Lifschitz-van der Waals/acid-base (LW/AB) method. This paper theoretically studies the surface energy of the homopolymer side of corona- modified CPP film, based on LW/AB method. By injecting three drops of ethylene glycol, water, and diiodomethane with different polarities on the surface of the CPP film and with the help of spectroscopy, the contact angle of the three liquids with the solid surface was obtained. Finally, the surface energy of CPP was calculated using the LW/AB equation. In the calculations, it was shown that the surface energy of one side of the corona-modified CPP film is higher than the other side.