INFLUENCE OF THE MORPHOLOGY OF POLYPROPYLENE FILMS ON THE FORMATION AND EVOLUTION OF IRRADIATION-INDUCED PEROXY-RADICALS

To gain some knowledge on the influence of a substrate morphology upon radiochemical grafting efficiency, the formation and the evolution of irradiation induced peroxy-radicals were measured by ESR in two polyp ropylene (PP) films of different origins. The creation rate of peroxy- radicals was found to be almost proportional to the irradiation dose i n the film presenting the best crystallinity, the bi-oriented PP, whil e it saturates in the unoriented one. The recombination kinetics of th e radicals appeared to be controlled by their diffusion in the matrix and the corresponding diffusion coefficients are dependent on the matr ix itself and on its evolution under irradiation. It is suggested that the crystalline order of the matrix is the parameter governing the mo bility and thus the lifetime of the radicals. (C) 1994 John Wiley & So ns, Inc.