Graft copolymerization of acrylic acid to nylon 6 by mutual irradiation. II. The influence of cupric ions

In the γ‐irradiation in vacuo of nylon 6 film in the presence of aqueous acrylic acid and different concentrations of cupric chloride, the following relationships have been obtained: R H ∝ [CuCl 2 ] −1.0 and R G ∝ [CuCl 2 ] −0.3 Here [CuCl 2 ] is the concentration of cupric chloride in the bulk solution, and R H and R G denote the initial rates of homopolymerization and grafting, respectively. The values of −1.0 and −0.3 for the exponents indicate that the cupric ion is a less effective chain terminator in the film on account of its lower concentration there. Analyses of films grafted in different media demonstrate the copper content of a film to be independent of both the concentration of monomer in the solution and the degree of swelling. The copper content is primarily a function of the total poly(acrylic acid) present, i.e., (grafted species plus occluded homopolymer). Thus, at high doses, where the total poly(acrylic acid) associated with a film is significant, the grafting curves exhibit a falling off, and complex formation between cupric ion and a growing chain is considered a likely contributory factor.