ABSTRACT
Abstract-Different benzophenone type photo-initiators were photo-grafted onto polypropylene. The polymer surfaces were analysed by means of contact angle measurements, UV spectroscopy and FTIR-ATR. The photo-initiator modified surfaces showed a higher wettability and higher surface energies increasing from 26 mJ/m2 for the pure polypropylene surface up to 36 mJ/m2 for the photo-initiator modified surfaces. Different acrylates were subsequently grafted efficiently onto the photo-initiator modified polymer surfaces. FTIR-ATR and contact angle measurements confirmed the presence of the grafted chains. The surface energy of the acrylate grafted samples thus increased up to 70 mJ/m2 depending on the type of acrylate used. Finally UV curable powder coatings were applied onto the photo-initiator modified polypropylene substrates and the adhesion was found to be improved. Adhesion was measured by the pull-off test and a value of approximately 0.20 MPa was obtained for pure polypropylene while the photo-initiator modified polypropylene reached pull-off value of 2.00 MPa.
