C-13 NMR MEASUREMENTS OF POLYBUTADIENE LOCAL DYNAMICS IN DILUTE-SOLUTION - FURTHER EVIDENCE FOR NON-KRAMERS BEHAVIOR

TitleC-13 NMR MEASUREMENTS OF POLYBUTADIENE LOCAL DYNAMICS IN DILUTE-SOLUTION - FURTHER EVIDENCE FOR NON-KRAMERS BEHAVIOR
Publication TypeJournal Article
Year of Publication1994
AuthorsZhu, W., D. J. Gisser, and M. D. Ediger
JournalJournal of Polymer Science Part B-Polymer PhysicsJournal of Polymer Science Part B-Polymer PhysicsJournal of Polymer Science Part B-Polymer Physics
Volume32
Pagination2251-2262
Date PublishedOct
Type of ArticleArticle
ISBN Number0887-6266
Accession NumberWOS:A1994PH55800012
KeywordsACTIVATION ENERGY, AMPLITUDE ISOMERIZATION RATES, AROCLOR, CIS-POLYBUTADIENE, DIPHENYL BUTADIENE, KRAMERS EQUATION, LOCAL POLYMER DYNAMICS, NMR, NUCLEAR-MAGNETIC-RESONANCE, PHOTOCHEMICAL ISOMERIZATION, POLYMER-SOLUTIONS, POLYSTYRENE AROCLOR, SEGMENTAL DYNAMICS, SOLUTIONS, SOLVENT DYNAMICS, T-1, VISCOSITY, VISCOSITY DEPENDENCE
Abstract

The local segmental dynamics of cis-polybutadiene in dilute solutions have been investigated using natural abundance C-13 NMR spectroscopy. The time integral of the C-H orientation autocorrelation function [sigma] is extracted from T-1 measurements in five solvents covering a viscosity range of two decades. The hydrodynamic Kramers' equation, which is generally assumed to be appropriate for local polymer dynamics in dilute solution, cannot describe these results. [sigma] is found to depend upon the solvent viscosity eta raised to the 0.33 power whether eta is varied by changing the temperature or the solvent. This apparent power law behavior has been observed for other polymers in dilute solution and can be rationalized if the solvent is viewed as viscoelastic. This view is supported by experimental results which show that local polymer dynamics can occur as much as an order of magnitude faster than solvent reorientation. Trends for a mixed microstructure polybutadiene are similar to those of cis-polybutadiene. (C) 1994 John Wiley & Sons, Inc.

Short TitleJ. Polym. Sci. Pt. B-Polym. Phys.J. Polym. Sci. Pt. B-Polym. Phys.
Alternate JournalJ. Polym. Sci. Pt. B-Polym. Phys.