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Positron lifetime spectroscopy for investigation of thin polymer coatings

Author
Singh, Jag J.
Published
Feb 1, 1993.
Physical Description
1 electronic document
Additional Creators
Sprinkle, Danny R. and Eftekhari, Abe
Online Version

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Summary
In the aerospace industry, applications for polymer coatings are increasing. They are now used for thermal control on aerospace structures and for protective insulating layers on optical and microelectronic components. However, the effectiveness of polymer coatings depends strongly on their microstructure and adhesion to the substrates. Currently, no technique exists to adequately monitor the quality of these coatings. We have adapted positron lifetime spectroscopy to investigate the quality of thin coatings. Results of measurements on thin (25-micron) polyurethane coatings on aluminum and steel substrates have been compared with measurements on thicker (0.2-cm) self-standing polyurethane discs. In all cases, we find positron lifetime groups centered around 560 psec, which corresponds to the presence of 0.9-A(exp 3) free-volume cells. However, the number of these free-volume cells in thin coatings is larger than in thick discs. This suggests that some of these cells may be located in the interfacial regions between the coatings and the substrates. These results and their structural implications are discussed in this report.
Other Subject(s)
Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 19930008756.
Accession ID: 93N17945.
NAS 1.15:4421.
NASA-TM-4421.
L-17165.
Terms of Use and Reproduction
No Copyright.
View MARC record | catkey: 15672621