HYDROPHILIC MODIFICATION ON SURFACE OF POLYPROPYLENE FILMS WITH POLYDOPAMINE

Based on the strong adhesive behavior of polydopamine on solid surface,PP film were modified via dispersing in a dopamine solution at room temperature. The properties of modified films were mainly characterized by contact angle measurements (CA) and scanning electron microscopy (SEM). The peeling strength was measured using a T-peel test performed on an electronic universal testing machine. The results of CA showed that the hydrophilic properties of the film could be controlled by adjusting pH value, dopamine concentration and reaction time. The effects of polydopamine on film surface morphologies were investigated by SEM. The contact angle reduced from 105 degrees to about 63 degrees under the reaction conditions of pH 8.5, the concentration at 2.0 g/L for 24 h,which meant the hydrophilicity of PP films was significantly improved by the attachment of polydopamine. The durability of the modified layer was also investigated. The results indicate that the modified surface could retain its hydrophilic properties after immersing in water at 60 degrees C for 48 h or in a solutions of pH values between 1.0 and 10.0. There was no polydopamine dreg evidently split away from the PP film after durability test. Moreover, the peeling strength between polydopamine and PP film was about (25.3 +/- 3.0) N/m.