| Abstract
| - Molecular dynamics simulations were employed in bulk polyisobutylene, to provide a detailedcharacterization of the methyl dynamics and to examine its relation to the β-relaxation as described bydifferent experimental techniques. The simulation results were compared to new 13C NMR measurementsprobing methyl motion at temperatures above the glass transition, as well as to lower temperatureliterature NMR data. It was found that the 13C NMR results, and those for the β-relaxation reported bydielectric relaxation spectroscopy and neutron scattering experiments, can be interpreted on a commonbasis through a coupling mechanism between methyl rotation and a recently described fast relaxationmotion associated with the chain backbone. In addition, a molecular mechanism for the description ofthe dielectric β-process observed in polyisobutylene is proposed, and investigated by simulations.
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