Ion beam modification of polyimide membranes for gas permeation
Abstract
The irradiation of 6FDA (hexafluorodianhydrid) polyimide films, produced for gas separation, with ion beams leads to dramatic modifications of their permeability to hydrogen and methane. The irradiation of the PI membranes with 2 MeV α particles induces a permeability increase for both gases, whereas a reduction of the permeability to CH 4 is obtained for a bombardment of the films with 170 keV N + at fluences larger than 10 15 cm -2. The modification of the diffusion through the membranes has been interpreted using a multilayer model, which enabled the calculation of the intrinsic permeabilities of the irradiated layers. The second irradiation regime induces a significant selectivity enhancement. The improvement of the selective properties of the irradiated membranes is interpreted in terms of modification of the elementary free volumes involving the reduction of the mean size.
- Publication:
-
Nuclear Instruments and Methods in Physics Research B
- Pub Date:
- November 1995
- DOI:
- 10.1016/0168-583X(95)00531-5
- Bibcode:
- 1995NIMPB.105..130E