Surface photografting polymerization of vinyl acetate (Vac), maleic anhydride (MAH), and their charge transfer complex (CTC). III. VAc(3)

Vinyl acetate (VAc) was grafted onto low-density polyethylene (LDPE) substr ates by UV irradiation with benzophenone (BP) as the photoinitiator. BP pre absorbed film samples and BP precoated film samples were prepared in advanc e and applied as the substrates onto which VAc was photografted, together w ith the method in which BP was dissolved in VAc directly. In addition, the efficiency of the polymerizations applying the preirradiation technology wa s examined. The conversion percent, grafting percent, and grafting efficien cy were determined by a gravimetric method, The contact angles of the graft ed films against water were also measured. The results: show that BP preabs orbing and precoating were favorable to grafting polymerization, especially the BP precoating method, which was due to its simple operation and the ca se of controlling the amount of BP. The diffusion of BP and VAc through the substrates proved to be an important factor for grafting polymerization. T hrough UV irradiation, dormant groups can be introduced onto LDPE film, whi ch may be activated again by UV irradiation or by heating, leading to the f ormation of free radicals. Grafting polymerization can be initiated during the activation process in the presence of monomer. (C) 2001 John Wiley & So ns, Inc.