Polypropylene films modified by air plasma and feather keratin graft

Polypropylene (PP) films were grafted respectively with two different processes: air plasma graft (APG) and post-plasma grafting (PPG) using feather keratin. The graft results were compared by measuring contact angles, printability, ageing test and surface chemical composition analysis. The results showed that the surface hydrophilic and printing properties of the PP films after PPG were better than after APG. The contact angles went down from 34.7° to less than 10° and could sustain to 28° at the end of the test (30 days). The analyses of the C1s and N1s peaks by X-ray photoelectron spectroscopy (XPS) illustrated that polar groups, especially nitrogen-containing groups C–NHx and CO–NH, were introduced on the PP surface after PPG. The mechanisms of PPG were briefly discussed.