Modifying the MRI, elastic stiffness and electrical properties of polyvinyl alcohol cryogel using irradiation

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DOIResolve DOI: http://doi.org/10.1016/j.nimb.2007.04.111
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TypeArticle
Journal titleNuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
ISSN0168-583X
Volume263
Issue1
Pages239244; # of pages: 6
SubjectPVA-C; irradiation; conductivity; MRI relaxation times
AbstractThe aim of this work was to study the effect of radiation on the elastic stiffness, electrical and MRI properties of polyvinyl alcohol (PVA)-based cryogel (PVA-C). The PVA-C samples were irradiated with a 60C0 γ-source, at 2.18 × 106 Rads. The indentation measurements (an indication of elastic stiffness) reduced by about 14.6% for PVA-3C and 5.7% PVA-6C after irradiation, indicating that the material became harder/stiffer. It was found that MRI relaxation times provide an alternative and non-destructive method to evaluate the radiation effect on PVA-C. The T1 of PVA-C that had undergone three freeze thaw cycles decreased with irradiation by 10%, 25% and 35% at 1 T, 1.89 T and 3 T respectively. The T1 of PVA-C that had undergone six freeze thaw cycles decreased with irradiation by 18%, 15% and 11% at 1 T, 1.89 T and 3 T respectively. The T2 of PVA-C decreased with irradiation only at 1T, however this change is hypothesized to be due to the interaction of two spin pools in the gel. The electrical conductivity (σ) and permittivity constant (ε) of the unirradiated and γ-irradiated PVA-C samples were measured at different frequencies in the range 40 Hz to 1 MHz. The results demonstrated that the conductivity increased with irradiation by 50% for PVA-3C (three freeze thaw cycles) and 75% for PVA-6C (six freeze thaw cycles) at frequencies greater than 1 KHz.The permittivity decreased with irradiation up to 25% for 3C and 35% for 6C at frequencies less than 1 KHz.
Publication date
LanguageEnglish
AffiliationNRC Industrial Materials Institute; National Research Council Canada
Peer reviewedYes
NPARC number21274334
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Record identifier4f52ac10-6815-4ee4-a1a7-be6c84a96de9
Record created2015-03-10
Record modified2016-05-09
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