Characterization of a nylon 6/poly(methyl acrylate) copolymer produced by radiation grafting

Acrylic acid has been grafted onto nylon 6 by the mutual γ-irradiation technique. Methods are described for removing poly(acrylic acid) homopolymer and ungrfted nylon, the latter involving intermediate conversion to the calcium ionomer. The pure graft copolymer in its methylated form, viz., nylon 6/poly(methyl acrylate), NY/PMA, was characterized by light scattering in mixed solvents to yield the true molecular weight (3.2 × 106) as well as the molecular weights MPMA(domain) and MNY(domain) of the PMA and NY portions, respectively. The molecular weight MPMA of the grafts was measured after hydrolysis of the backbone, and the molecular weight MNY of the backbone was determined via a previously devised indirect procedure. Comparisons of MPMA(domain) with MPMA and of MNY(domain) with MNY gave ˜ 7 nylon chains and ˜ 17 poly(methyl acrylate) chains per copolymer molecule. Chain transfer and bimolecular terminatin during grafting are proposed as probable contributory factors to the branched structure of the copolymer.