ISSN:
1436-2449
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Summary The proton enhanced magic angle 13C-NMR spectrum of cyclotetracosane exhibits one sharp signal only at room temperature indicating that all carbons within the ring have identical average conformational surrounding at the NMR time scale. A highly mobile pseudorotating phase is concluded. The average ratio of the gauche and of the anti conformers has been calculated from the chemical shift of these cyclotetracosane carbons applying the anti conformer chemical shift of n-alkanes and that of the gauche conformer derived from solution slow exchange spectra of meso 4,5-dimethyloctane. Thus, polyethylene spectra of EARL and VANDERHART could be interpreted in terms of the anti-gauche ratio within the amorphous folds of polyethylene. The conformational balance within the amorphous region of polyethylene is compared with that of erythrodiisotactic poly (1,2-dimethyltetramethylene).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00265155
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