NMR Imaging of Elastomeric Materials
Annual rept. 1 Jul 1989-31 Jul 1990,
ARKANSAS UNIV FOR MEDICAL SCIENCES LITTLE ROCK
Pagination or Media Count:
NMR imaging has been applied to some elastomeric materials of industrial and military interest. The T2 spin-spin relaxation times of common elastomers, particularly after filling and curling, are sufficiently short that spin-echo sequences at submillisecond echo times cannot produce T2-independent images. The sensitivity to T2 potentially makes spin echo imaging a good probe of elastomer blend composition, as demonstrated for a series of filled and cured cis-polybutadiene, styrene-butadiene rubber blends. The technique can be used to distinguish good and bad carbon black dispersion in actual tire tread samples. The configuration of polyester tire cord, voids, rubber layer boundaries, apparent migration of additives, and other inhomogeneities can be detected in end-product tire samples. NMR images have been obtained for four porous glass disks of different porosities as models of materials such as oil cores. The mottled appearance often seen for such images is attributed largely to insufficient signal-to-noise ratio, and not pore structures. Comparison of spin- echo and gradient-echo images demonstrates the defect-magnification effect of the gradient-echo.
- Atomic and Molecular Physics and Spectroscopy