Characterization of MMA/LDPE copolymer films obtained by gamma radiation

Gamma induced grafting in crystalline or vitreous polymers produces a number of polymer radicals which remain trapped in the rigid polymer matrix. Grafting takes place during the diffusion process and it is accomplished as soon as the polymer is swollen upon which the radicals acquire enough mobility to combine among them. Since graft polymerization involves processes such as polymeric free-radicals generation, monomer molecules penetration and incorporation into the polymer matrix, it provides a promising field for the application of the Positron Annihilation Lifetime (PAL) technique. In the present work PAL was applied to the study of the microstructure of the graft copolymer of methyl methacrylate (MMA) onto low-density polyethylene (LDPE). Micrographs were taken along the copolymer formation process which show a characteristic morphology of graft copolymers. Direct method of g-induced graft polymerization was the best technique to carry on the preparation of the MMA/LDPE copolymer. (Author)