F. Junker et Ws. Veeman, XENON SELF-DIFFUSION IN ORGANIC POLYMERS BY PULSED-FIELD GRADIENT NMR-SPECTROSCOPY, Macromolecules, 31(20), 1998, pp. 7010-7013
Xenon self-diffusion coefficients of commercially available organic po
lymers have been determined by application of pulsed field gradient (P
FG) NMR spectroscopy. Xenon diffusion in the elastomeric terpolymer et
hylene-propylene-diene (EPDM) was found to be about 20 times faster th
an in the more rigid semi-crystalline poly(propylene) (PP). In a polym
er blend of both materials consisting of 80% PP and 20% EPDM both diff
usion coefficients are in the same range and between the values of the
pure materials. As SEM pictures show, this incompatible blend consist
s of small EPDM domains (1-3 mu m) within the PP matrix. The root mean
square displacement of xenon within the time interval of the PFG NMR
experiment is greater than the domain sizes of EPDM. These results als
o evidence that xenon in this blend is mainly absorbed in EPDM domains
and in the PP matrix near the PP/EPDM interface.