ISSN:
0887-6266
Keywords:
NMR relaxation
;
local chain motion
;
PHO
;
temperature dependence
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Variable-temperature 13C NMR spin-lattice relaxation times (T1) and Nuclear Overhauser Enhancements (NOE) at two magnetic fields have been used to study the dynamics of the amorphous part of a semicrystalline sample (33% of crystallinity) of poly(β-hydroxyoctanoate) (PHO). The interpretation of the relaxation data of the backbone carbons was made by employing a number of motional models. Among these, the DLM model offered the best interpretation of the relaxation data in terms of conformational transitions and librational motions of the backbone C—H vectors, and proved to be superior to unimodal distribution functions. The interpretation of temperature- and frequency-dependent T1 and NOE data of the carbon nuclei in the n-pentyl side chain was made by employing a newly developed composite spectral density function for multiple internal C—C bond rotations of restricted amplitude and chain segmental motion. The temperature dependence of the linewidths of the various protonated carbon resonances of PHO has been discussed in terms of the semicrystalline character of this polymer. © 1995 John Wiley & Sons, Inc.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/polb.1995.090330304
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