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Molecular dynamics in thin films of isotactic poly(methyl methacrylate)
L Hartmann1, W Gorbatschow, J Hauwede
1University of Leipzig, Department of Physics, D-04103 Leipzig, Germany.
The European Physical Journal. E, Soft Matter
|March 11, 2004
Abstract:
The molecular dynamics in thin films (18 nm-137 nm) of isotactic poly(methyl methacrylate) (i-PMMA) of two molecular weights embedded between aluminium electrodes are measured by means of dielectric spectroscopy in the frequency range from 50 mHz to 10 MHz at temperatures between 273 K and 392 K. The observed dynamics is characterized by two relaxation processes: the dynamic glass transition (alpha-relaxation) and a (local) secondary beta-relaxation. While the latter does not depend on the dimensions of the sample, the dynamic glass transition becomes faster (