Atomic motions in the alpha-beta merging regime of 1-4 polybutadiene: A molecular dynamics simulation study

Narros, A.; Arbe, A.; Alvarez, F.; Richter, D.; Colmenero, J.

doi:10.1063/1.2937733

Journal Article

PreJuSER-62975

Atomic motions in the alpha-beta merging regime of 1-4 polybutadiene: A molecular dynamics simulation study

Narros, A. ; Arbe, A. ; Alvarez, F. ; Colmenero, J. ; Richter, D.FZJ*

2008
American Institute of Physics Melville, NY

The journal of chemical physics 128, 224905 (2008) [10.1063/1.2937733]

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Please use a persistent id in citations: http://hdl.handle.net/2128/19025 doi:10.1063/1.2937733

Abstract: We present fully atomistic molecular dynamics simulations on 1,4-polybutadiene in a wide temperature range from 200 to 280 K, i.e., in the region where the alpha- and beta-relaxations merge and above. A big computational effort has been performed-especially for the lowest temperatures investigated-to extend the simulation runs to very long times (up to 1 mus for 200 K). The simulated sample has been carefully validated by using previous neutron scattering data on the real sample with similar microstructure. Inspecting the trajectories of the different hydrogens in real space, we have observed a heterogeneous dynamical behavior (each kind of hydrogen moves in a different way) with signatures of combined hopping and diffusive motions in the whole range investigated. The application of a previously proposed model [Colmenero et al., Europhys. Lett. 71, 262 (2005)] is successful and a characterization of the local motions and diffusion is possible. The comparison of our results to those reported in the literature provides a consistent scenario for polybutadiene dynamics and puts into a context the different experimental observations. We also discuss the impact of the hopping processes on the observation and interpretation of experimentally accessible magnitudes and the origin of the deviations from Gaussian behavior in this system.

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