抄録
The mechanism of deuteration of nylon 4 membranes by D2O vapor has been investigated in relation to the sorption of water.
The degree of deuteration of nylon 4 at 25°C was saturated at 17.5, 25 and 31% by cumulative contact with D2O vapor for 5, 30 and 60min a time, respectively, and equilibrated at the value of 38% by a long contact.
On the other hand, the reduced sorption curve for water showed a sigmoidal one at 25°C.
To these experimental results, Long's diffusion theory based on the time dependence of surface concentration of penetrant was applied under an assumption of a proportional relation of the degree of deuteration to the quantity of sorbed water. Long's parameters were obtained as β=1.6×10-2min-1 and DL=1.25×10-6cm2/min. By use of these parameters, water concentration distribution curves were calculated.
These results suggest that water molecules diffuse instantaneously into the center of membrane, and the quantity of sorbed water and the degree of deuteration increase uniformly throughout the membrane with gradual relaxation of hydrogen bonding of nylon 4 caused by water (D2O) sorbed in the earlier contact period.
