ISSN:
0887-6266
Keywords:
positron annihilation
;
polyimide
;
ion implantation
;
membrane
;
permeability
;
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
6FDA-pMDA polyimide membranes were implanted with 140 keV N+ ions to fluences between 2 × 1014 and 5 × 1015 cm-2. Variable energy positron annihilation spectra were taken and spectral features compared to previously reported changes in gas permeability and permselectivity of these membranes as a function of ion fluence. Positron data corroborate the explanation of these changes in terms of molecular damage caused by the implant: for fluences up to about 1 × 1015 cm-2, the concentration of irradiation-induced defects merely increases with implant fluence; while fluences exceeding this threshold value create a second type of positron annihilation site, thereby marking a distinct change in the structure of the polymer, which is responsible for the vast improvement of gas permselectivity data found at the same threshold fluence. PACS codes: 78.70.Bj - positron annihilation; 61.82.Pv - polymers, organic compounds; 61.72.Ww - doping and impurity implantation. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2413-2421, 1998
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
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