By courtesy of:
Man-Ho Kim,* Charles J. Glinka, Stephen A. Grot, and Walther G. Grot
Macromolecules 2006, 39, 4775-4787
and old study about its crystallinity:
Crystallinity in Perfluorosulfonic Acid Ionomers and Related Polymers
Howard W. Starkweather, Jr.
Macromolecules 1982, 15, 320-323