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Oxygen-17 and Proton Mr Microscopy in Materials Analysis

Published online by Cambridge University Press:  21 February 2011

G.D. Mateescu ,
R.A. Kinsey  and
G.M. Yvars
G.D. Mateescu
Affiliation:
Department of Chemistry, Case Western Reserve University Cleveland, Ohio 44106, USA
R.A. Kinsey
Affiliation:
B.F. Goodrich Research & Development Center Brecksville, Ohio 44141 USA
G.M. Yvars
Affiliation:
Department of Chemistry, Case Western Reserve University Cleveland, Ohio 44106, USA
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Abstract

Preliminary results of two applications of 17O/lH NMR microimaging (MRμI) are described. In the first case, it is shown that oxygen-17 MRμI presents a unique advantage in situations where a strong proton background hinders the analysis of water ingress in polymeric materials. This is illustrated with 17O-enriched water diffusion into an agar gel from a central well. While proton imaging cannot readily distinguish between exogenous and endogenous water, 17O imaging makes a clear differentiation, due to the fact that the natural abundance gel has virtually no 17O background. In the second case, proton MRμI was used to analyze the structure and performance of commercial time-release pellets (ProMacR) containing an active ingredient (surfactant) dispersed into an inert matrix. This was done after leaching the detergent with natural abundance water or after drying the leached sample and refilling the pores with water. Pores ranging in size from 25 to 325 μm diameter are clearly visualized. The 1H images have been quantitated with commercial image analysis software in terms of the total porosity and the individual pore characteristics. Two types of water can be separately imaged: “bound” water with restricted mobility (interacting with the polymer matrix), and “free” water (in large pools). The majority of water is in the bound state. It is possible to evaluate the control-release performance of the product from the size of the pores, the uniformity of dispersion and the time course of detergent-water exchange.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 217: Symposium U – Advanced Tomographic Imaging Methods for the Analysis of Materials , 1990 , 61
Copyright
Copyright © Materials Research Society 1991

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References

NOTES AND REFERENCES

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