Artifacts in Transverse Proton NMR Relaxation Studies of Elastomers.
Macromolecules 38, 1508-1512 (2005).
Transverse proton NMR relaxation of filled elastomers is shown to be subject to
magnetic field-dependent artifacts. Previous Hahn echo experiments on rubbers
filled with silica and carbon black conducted at high field (Luo et al.,
Macromolecules 37 (2004) 8000) suggested substantial increases in
cross-link density upon compounding, while data obtained at low field (20 MHz)
indicates virtually no filler effect and is in quantitative agreement with
results of more specific proton double-quantum experiments conducted at high
field. Further sources of error pertaining to relaxometric investigations of
elastomers in general, such as interrelations among poorly defined fitting
parameters and the limited applicability of the common Andersen-Weiss model, are