Migration of divalent ions in nylon 6 films

The migration of ions through a nylon-6 film is studied by MRI. For this study the paramagnetic ions Mn2+ and Cu2+ are used as they act as a contrast agent and are detectable by MRI. The ingress of water and ions in nylon occurs at different rates. First, water is absorbed in the nylon. Second, the ions slowly migrate through the nylon matrix. The transport mechanism of manganese ions is investigated by quantification of the MRI profiles and a Fickian diffusion behavior is found. Furthermore, the migration rate of ions in the polymer matrix is governed by the amount of water present. Water is needed to hydrate the ions and to plasticize the polymer matrix. Measurements with a deuterated solution show that the paramagnetic nature of the ions affects the signal of the guest water-hydrogen nuclei first. This implies that the ion is surrounded by water when situated in the polymer matrix. © 2014 Elsevier Ltd. All rights reserved