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Journal of the American Society for Mass Spectrometry
White II, Gregory V. ; White, Michael I. ; Bernstein, Robert B. ; Hochrein, James M.
Aged materials, such as polymers, can exhibit modifications to their chemical structure and physical properties, which may render the material ineffective for its intended purpose. Isotopic labeling was used to characterize low-molecular weight volatile thermal-oxidative degradation products of nylon 6.6 in an effort to better understand and predict changes in the aged polymer. Headspace gas from aged (up to 243 d at 138 °C) nylon 6.6 monomers (adipic acid and 1,6- hexanediamine) and polymer were preconcentrated, separated, and detected using cryofocusing gas chromatography mass spectrometry (cryo-GC/MS). Observations regarding the relative concentrations observed in each chromatographic peak with respect to aging time were used in conjunction with mass spectra for samples aged under ambient air to determine the presence and identity of 18 degradation products. A comparison of the National Institute of Standards and Technology (NIST) library, unlabeled, and isotopically labeled mass spectra (C-13 or N-15) and expected fragmentation pathways of each degradation product were used to identify the location of isotopically labeled atoms within the product's chemical structure, which can later be used to determine the exact origin of the species. In addition, observations for unlabeled nylon 6.6 aged in an O-18 enriched atmosphere were used to determine if the source of oxygen in the applicable degradation products was from the gaseous environment or the polymer. Approximations for relative isotopic ratios of unlabeled to labeled products are reported, where appropriate. © American Society for Mass Spectrometry, 2012.
Samberson, Jonell N. ; White II, Gregory V. ; White, Michael I. ; Pearl, Megan R.
White II, Gregory V. ; Samberson, Jonell N. ; White, Michael I. ; Hochrein, James M. ; Bernstein, Robert B.
White II, Gregory V.
Hochrein, James M. ; White II, Gregory V. ; Dirk, Shawn M. ; Samberson, Jonell N. ; Finnegan, Patrick S.
White II, Gregory V. ; White, Michael I. ; Hochrein, James M.
White II, Gregory V. ; White, Michael I. ; Hochrein, James M.
Samberson, Jonell N. ; White II, Gregory V. ; White, Michael I. ; Bernstein, Robert B. ; Hochrein, James M.
White II, Gregory V. ; Samberson, Jonell N. ; White, Michael I.
White II, Gregory V. ; Bernstein, Robert B.
White II, Gregory V. ; Bernstein, Robert B.
This document discusses open literature reports which investigate the damage effects of neutron and gamma irradiation on polymers and/or epoxies - damage refers to reduced physical chemical, and electrical properties. Based on the literature, correlations are made for an SNL developed epoxy (Epon 828-1031/DDS) with an expected total fast-neutron fluence of {approx}10{sup 12} n/cm{sup 2} and a {gamma} dosage of {approx}500 Gy received over {approx}30 years at < 200 C. In short, there are no gamma and neutron irradiation concerns for Epon 828-1031/DDS. To enhance the fidelity of our hypotheses, in regards to radiation damage, we propose future work consisting of simultaneous thermal/irradiation (neutron and gamma) experiments that will help elucidate any damage concerns at these specified environmental conditions.
White II, Gregory V. ; Samberson, Jonell N. ; White, Michael I. ; Hochrein, James M. ; Bernstein, Robert B.
White II, Gregory V. ; Samberson, Jonell N. ; White, Michael I. ; Hochrein, James M.
Proposed for publication in Polymer Degradation and Stability.
White II, Gregory V. ; Samberson, Jonell N. ; Ohlhausen, J.A. ; Hochrein, James M. ; Bernstein, Robert B.
White II, Gregory V. ; Samberson, Jonell N. ; White, Michael I. ; Hochrein, James M. ; Bernstein, Robert B.
White II, Gregory V. ; Samberson, Jonell N. ; White, Michael I. ; Hochrein, James M.
White II, Gregory V.
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