Accession Number:

ADA256034

Title:

NMR Imaging of Elastomeric Materials

Descriptive Note:

Final rept. 1 Jul 1989-30 Jun 1992

Corporate Author:

ARKANSAS UNIV FOR MEDICAL SCIENCES LITTLE ROCK

Report Date:

1992-08-31

Pagination or Media Count:

41.0

Abstract:

NMR imaging has been applied to elastomeric materials of industrial and military interest The T2 spin-spin relaxation times of common elastomers, particularly after filling and curing, are sufficiently short that spin-echo sequences at submillisecond echo times cannot produce T2-independent images. The sensitivity to T2 makes spin echo imaging a good probe of elastomer blend composition, as demonstrated for a series of filled, cured cis-polybutadiene, styrene-butadiene rubber blends. The technique can distinguish good and bad carbon black dispersion in actual tire tread samples. The configuration of non- metallic tire cord, voids, rubber layer boundaries, apparent migration of additives, and other inhomogeneities can be detected in end-product tire samples. Arrowhead patterns, arising from magnetic susceptibility differences for defects in carbon-black-filled elastomers, were attributed to graphitized coke particles from the carbon black. NMR images were obtained for 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 sequence seen previously for elastomers. The advantages of volume imaging, isotropic voxels in thin slices, and higher resolution are demonstrated for porous materials. defects, composites, spin echo, lithium-7, fluorine-19, carbon nuclear magnetic resonance, imaging, elastomers, tires, black, Interfaces, curing, filler, NMR imaging, relaxation coke.

Subject Categories:

  • Elastomers and Rubber
  • Surface Transportation and Equipment
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE