Surface grafting of polyethylene by mutual irradiation in methyl acrylate vapor

Abstract

Industrialization of the surface grafting process of polyethylene (PE) in methyl acrylate (MA) vapor is achieved by high-energy electron irradiation in a monomer vapor flow system. High-energy electron irradiation from electron accelerators, providing high dose rates more than 1 Mrad/min, produces surface grafts within less than 4 min irradiation time, whereas γ -ray irradiation from Co-60 sources, providing low dose rates less than 1 × 10 5 rad hr , requires at least 1 hr. Scale-up of the grafting chamber in electron-induced grafting causes rapid deposition of the vapor-phase homopolymerized poly(methyl acrylate) (PMA) film on the grafting PE surface. This deposition prevents grafting reactions on the underlying PE surface. By replacing the irradiated monomer vapor containing polymers and polymer radicals with fresh monomer vapor, the monomer vapor-nitrogen mixture gas flow system reduces the PMA deposition rate without reduction of the grafting rate.