Surface structure and adhesive properties of biaxially oriented polypropylene film grafted with poly(acrylic amide) using corona discharge

Corona discharge was explored as a means of forming chemically active sites on the surface of biaxially oriented polypropylene (BOPP) film. The active species formed in air was used to induce graft copolymerization of acrylic amide (AAM) in aqueous solution. The surface structure, hydrophilicity and adhesion of the grafted BOPP film were characterized by the extent of graf ting, electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), peel strength and contact angle measurements. Surface gr aft-copolymerization of AAM onto BOPP film by corona discharge in air can b e carried out with high efficiency. With increasing copolymerization time, the degree of grafting of AAM onto BOPP increases. The degree of grafting a chieved a relatively high value of 2.13 wt% for the conditions of I min cor ona discharge and a copolymerization reaction time of 2.5 hr in 20% AAM aqu eous solution at 70 degreesC. After corona discharge grafting, the contact angle of water on the BOPP film decreased and the peel strength increased c ompared with those for ungrafted BOPP film. The hydrophilicity and adhesion of BOPP were improved by surface graft copolymerization with AAM induced b y corona discharge.