For introducing high concentration of functional groups on the surface of polyester fibers, thin layer grafting of methacrylic acid (MA) was applied to polyester fiber by direct electron irradiation. Radial distribution of concentration of MA in the thin surface layer of the grafted fiber was examined by measuring the optical reflectivity of the surface dyed after concecutive alkali hydrolysis of the grafted fiber.
By the alkali treatment of graft fiber it became clear that the concentration of MA was relatively low on the fiber surface, showed a maximum at the inner part within 1μm from the surface, and then decreased toward the inner regions of the fiber.
From above results we expect that by shaving the surface by a proper quantity through alkali treatment and thus exposing the surface with the maximum concentration of functional group, we can give a high concentration of functional groups at the surface of polyester fibers. Actually MA graft polyester fibers showed excellent dyeability by grafting even below 1%, through alkali treatment.