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Moisture dependence of positron annihilation spectra in nylon-6Positron annihilation time spectra have been measured in nylon-6 samples as a function of their moisture content. The measured average long life component lifetime values are: 1722 + or - 47 ps (dry), 1676 + or - 40 ps (14.6 percent saturation value), 1719 + or - 26 ps (29.3 percent saturation value), 1720 + or - 35 ps (50 percent of saturation value), 1857 + or - 35 ps (78.1 percent saturation value), and 1936 + or - 57 ps (saturated). It appears that nylon-6 has a special affinity for water at low concentration levels where H2O molecules enter between the (C = O - H-N) chemical bonds between nylon molecular chains. As the water concentration increases beyond a critical level, nylon-6 specimens start trapping H2O molecules in other bond sites or potential wells. The trapped water increases the free volume in the test specimens and reduces Ps atom formation as well as its subsequent decay rate.
Document ID
19840058036
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Singh, J. J.
(NASA Langley Research Center Hampton, VA, United States)
St. Clair, T. L.
(NASA Langley Research Center Hampton, VA, United States)
Holt, W. H.
(NASA Langley Research Center Hampton, VA, United States)
Mock, W., Jr.
(U.S. Navy, Naval Surface Weapons Center Dahlgren, VA, United States)
Date Acquired
August 12, 2013
Publication Date
April 1, 1984
Publication Information
Publication: Nuclear Instruments and Methods in Physics Research
Volume: 221
ISSN: 0167-5087
Subject Category
Nuclear And High-Energy Physics
Accession Number
84A40823
Distribution Limits
Public
Copyright
Other

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