Dresden 2009 – wissenschaftliches Programm
CPP 16.1: Poster
Dienstag, 24. März 2009, 14:00–16:30, P3
Temperature dependence of positron annihilation in high permeability polymers: Teflons AF — •Klaus Rätzke1, Jan Kruse1, Franz Faupel1, Yuri Yampolskii2, Victor Shantarovich3, and Günter Dlubek4 — 1Faculty of Engineering, University of Kiel, Germany — 2A.V. Topchiev Institute of Petrochemical Synthesis, Moscow, Russia — 3N.N.Semenov Institute of Chemical Physics, Moscow, Russia — 4Institute for Innovative Technologies, Köthen/Halle, Germany
The performance of polymeric membranes for gas separation is given by the free volume. Positron annihilation lifetime spectroscopy (PALS) is an accepted technique for investigation of free volume; the ortho-Positronium (o-Ps) lifetime is directly related to the mean hole size. PALS was done on amorphous Teflon AF 1600 and AF 2400. (copolymers of tetrafluoroethylene and 2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole units). From the data mean hole size and width were calculated. Both polymers show large o-Ps lifetimes (=> large hole sizes) and glass transition near the expected values. AF 2400 shows a non-linear temperature dependence of the ortho-positronium lifetime, extraordinarily large mean values of o-Ps lifetimes and the widths of the lifetime distributions. Explanations will be discussed in relation to the microstructure of the copolymer.
M. Rudel, J. Kruse, K. Rätzke, F. Faupel, Y. P. Yampolskii, V. P. Shantarovich, G. Dlubek, Macromolecules, 41 (2008) 788.
G. Dlubek, J. Pionteck, K. Rätzke, J. Kruse, F. Faupel, Macromolecules (2008); 41; 6125.