Factor analysis of time domain NMR data: crystallinity of poly(tetrafluoroethene)
1997; Elsevier BV; Volume: 344; Issue: 3 Linguagem: Inglês
10.1016/s0003-2670(97)00058-5
ISSN1873-4324
AutoresNigel J. Clayden, Ralph J. Lehnert, S. Turnock,
Tópico(s)Solid-state spectroscopy and crystallography
ResumoFactor analysis was applied to the 19F NMR time domain data of a set of 38 PTFE samples of varying crystallinity. The largest eigenvalue corresponding to 99.62% of the variance between the NMR data sets is associated with the correlation of monotonically decaying signals. Factor 1 associated with this eigenvalue was poorly correlated with the PTFE crystallinity. On the other hand excellent correlations were found between X-ray diffraction, differential scanning calorimetry, density, FT-IR and Raman indicators of crystallinity and factors 2 and 3 derived from the NMR data. The repeatability of the NMR data was excellent; the variation in factor 2 implying a %RSD of only 0.2% in the resulting crystallinity. On the other hand the reproducibility was poorer with a %RSD of 2.8% when no special precautions are taken to ensure equivalent acquisition conditions.
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