The quantitative evaluation of a 50.3 MHz 13C NMR methyl spectrum of a particular stereoisomer of polypropylene, called hemiisotactic (hit-PP), was performed by a full lineshape fitting procedure. This sample presents a dramatic selection between stereosequences and a characteristic pattern of signal intensities. The results are compared with a general statistical approach, leading to the conclusions that the structure of hit-PP is almost pure (96%). Also, small deviations from the ideality are accounted for. In this way linewidths and chemical shifts have been established for nine nonads and five undecads of monomer units, calling for a sensitivity to carbon atoms distant up to ten bonds.
UNDECAD RESOLUTION OF POLYPROPYLENE STEREOSEQUENCES - QUANTITATIVE-EVALUATION OF C-13 NMR METHYL SPECTRUM / P. SOZZANI, C. OLIVA. - In: JOURNAL OF MAGNETIC RESONANCE. - ISSN 0022-2364. - 63:1(1985), pp. 115-124.
UNDECAD RESOLUTION OF POLYPROPYLENE STEREOSEQUENCES - QUANTITATIVE-EVALUATION OF C-13 NMR METHYL SPECTRUM
C. OLIVAUltimo
1985
Abstract
The quantitative evaluation of a 50.3 MHz 13C NMR methyl spectrum of a particular stereoisomer of polypropylene, called hemiisotactic (hit-PP), was performed by a full lineshape fitting procedure. This sample presents a dramatic selection between stereosequences and a characteristic pattern of signal intensities. The results are compared with a general statistical approach, leading to the conclusions that the structure of hit-PP is almost pure (96%). Also, small deviations from the ideality are accounted for. In this way linewidths and chemical shifts have been established for nine nonads and five undecads of monomer units, calling for a sensitivity to carbon atoms distant up to ten bonds.Pubblicazioni consigliate
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