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A solid state NMR study on crystalline forms of nylon 6
Author(s) -
Okada Akane,
Kawasumi Masaya,
Tajima Ichiro,
Kurauchi Toshio,
Kamigaito Osami
Publication year - 1989
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1989.070370519
Subject(s) - dihedral angle , hydrogen bond , magic angle spinning , hyperconjugation , crystallography , delocalized electron , intermolecular force , solid state nuclear magnetic resonance , materials science , chemistry , nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , molecule , stereochemistry , organic chemistry , physics
High‐resolution 13 C‐NMR spectra were studied for two different crystalline structures of nylon 6 in the solid state by the cross polarization/magic angle spinning (CP/MAS) method. Two crystalline structures, α‐form and γ‐form, gave different chemical shifts for methylene carbons. The results showed that the hydrogen bonds between intermolecular chains are stronger in the γ‐form than in the α‐form. This strongly supports the results of the X‐ray study of nylon 6 by Malta et al. Our results also showed that interamolecular delocalization of positive charges occurs in the γ‐form through hyperconjugation in which the dihedral angle between the π bond and neighboring σ bonds is 30° while no such effect can be expected in the α‐form in which the angle is 0°.