RADIATION-INITIATED GRAFT-COPOLYMERIZATION OF ACRYLIC-ACID AND VINYL-ACETATE ONTO LDPE FILMS IN 2 INDIVIDUAL STEPS

Radiation-induced grafting of vinyl acetate (VAc) and acrylic acid (AA c) onto low-density polyethylene (LDPE) films was carried out in two i ndividual steps: initially, the polymer substrate was grafted either w ith VAc or AAc and the grafted film thus obtained was grafted with the other monomer. The graft copolymerization of AAc onto LDPE-g-PVAc fil ms was enhanced when the content of PVAc is low. This is due to the hi gh polarity and hydrophilicity of AAc. On the other hand, the grafting of VAc onto LDPE-g-PAAc films was restricted due to the difficulties of VAc diffusion through the crosslinked grafted chains of PAAc. The i nfluence of inhibitor and monomer concentration on the degree of graft ing was studied. The addition of 2wt% of Mohr's salt effectively reduc ed the homopolymerization of monomer during the irradiation process. T he dependence of the grafting rate upon VAc concentration was found to be of 1.5 order. Some selected properties of the graft copolymers, sw elling behaviour and electrical properties, were investigated.