Radiation-Induced Graft Copolymerization of Alkyl Methacrylates onto Polypropylene

Abstract

KAWASE, KAORU, AND HAYAKAWA, KIYOSHI. Radiation-Induced Graft Copolymerization of Alkyl Methacrylates onto Polypropylene. Radiation Res. 30, pp. 116-128 (1967). Six alkyl methacrylates have been grafted onto polypropylene fibers by y-irradiation by two techniques. In the grafting in which backbone polymer was dipped into liquid monomer (liquid-phase grafting), large differences in the extent of grafting were observed with the monomers, together with a remarkable acceleration of grafting rates. Monomers such as n-butyl and n-propyl methacrylates grafted to a very high extent, but the efficiencies of the grafting of isobutyl and isopropyl methacrylates were very low. From investigations on the homopolymerization occurring together with the grafting, bulk polymerization, and the swelling capability of grafted products, the differences in the grafting with monomers are explained in terms of differences in the relative concentration of monomers in the fibers. In the grafting in which the backbone polymer was suspended in the vapor of the monomer (gas-phase grafting), the rate of grafting was linear with the vapor pressure of the monomer. Results of grafting at a constant vapor pressure showed that the differences in extent of grafting and in the gel effect were much less, compared with those in the liquid phase, and in general the results were similar to those for bulk polymerization of methacrylates.