High-resolution carbon-13 nuclear magnetic resonance of trigonal and orthorhombic crystals of poly(oxymethylene)

exp 13 C NMR spectra of a needle-like single crystal of trigonal poly(oxymethylene) (t-POM) have been investigated in comparison with those of ordinary semicrystalline samples of t-POM. The exp 13 C signal in the single crystal splits into a doublet at 88.5 and 87.7 ppm in contrast to the singlet at...

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Bibliographic Details
Published in:Macromolecules 1990-06, Vol.23 (12), p.3051-3055
Main Authors: Kobayashi, Masamichi, Murano, Masao, Kaji, Atsushi
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Organic polymers
Physicochemistry of polymers
Properties and characterization
Structure, morphology and analysis
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Summary:exp 13 C NMR spectra of a needle-like single crystal of trigonal poly(oxymethylene) (t-POM) have been investigated in comparison with those of ordinary semicrystalline samples of t-POM. The exp 13 C signal in the single crystal splits into a doublet at 88.5 and 87.7 ppm in contrast to the singlet at 88.4 ppm in the semicrystalline samples. The split pattern is ascribed to the inequivalent monomeric units in the crystal field of the t-POM lattice. The corresponding exp 13 C signal of a plate-shaped single crystal of orthorhombic POM(0-POM) appears at 82 ppm as a singlet as anticipated from the space group of o-POM. The large chemical shift difference (6 ppm) between t-POM and o-POM was interpreted in terms of the intramolecular gamma gauche shielding and the intermolecular packing effect. Spectra. 25 ref.--AA
ISSN:0024-9297
1520-5835
DOI:10.1021/ma00214a005