WATER PERMEABILITY THROUGH NYLON 6 MEMBRANES GRAFTED WITH HYDROPHILIC MONOMERS

Abstract

Diffusive and hydraulic permeabilities of water through nylon 6 (GN) membranes grafted with acrylic acid (AA), acrylamide (AM), and p-styrenesulfonic acid (SS) were investigated. The diffusion coefficient of D₂O (D) through each kind of GN membrane increased with increasing the volume fraction of water (H) in swollen membrane. It was found that the free volume theory of diffusion is applicable to the diffusion of D₂O through the GN membranes with high H. However, In D gradually decreased with increasing (1/H)-1 in different ways for AA- and AM-GN membranes at low H region with less than 0.5. The state of sorbed water may contribute to the diffusion of water in the GN membrane with low H. On the other hand, close relationships were observed between the hydraulic permeability coefficient (K) of water and H. Water permeates through the membrane with low H mainly by diffusion even under a hydraulic pressure gradient, and water transport is predominantly due to the viscous flow in the region of high H.