Atomistic simulation of bulk mechanics and local dynamics of amorphous polymers

Lyulin, Alexey V. and Li, J. and Mulder, Tim and Vorselaars, Bart and Michels, M. A. J. (2006) Atomistic simulation of bulk mechanics and local dynamics of amorphous polymers. Macromolecular Symposia, 237 (1). pp. 108-118. ISSN 1022-1360

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Abstract

In order to have better insight into the polymer specifics of the dynamic glass transition molecular dynamics (MD) computer simulations of three glass-formers have been carried out: low-molecular-weight isopropylbenzene (iPB), brittle atactic polystyrene (PS) and tough bisphenol A polycarbonate (PC). Simulation of the uniaxial deformation of these mechanically different types of amorphous polymers shows that the mechanical experimental data could be realistically reproduced. Now the objective is to study the local orientational mobility in the non-deformed isotropic state and to find the possible connection of the segmental dynamics with the different bulk mechanical properties. Local orientational mobility has been studied via Legendre polynomials of the second order and CONTIN analysis. Insight into local orientational dynamics on a range of length- and time scales is acquired. The fast transient ballistic process describing the very initial part of the relaxation has been observed for all temperatures. For all three simulated materials the slowing down of cage escape (α-relaxation) follows mode-coupling theory above Tg, with non-universal, material-specific exponents. Below Tg universal activated segmental motion has been found. At high temperature the α process is merged with the β process. The β process which corresponds to the motions within cage continues below Tg and can be described by an activation law.

Keywords:Glass transition, Polymer dynamics, computer modeling, mechanical properties, relaxation
Subjects:F Physical Sciences > F300 Physics
F Physical Sciences > F162 Polymer Chemistry
F Physical Sciences > F320 Chemical Physics
F Physical Sciences > F310 Applied Physics
H Engineering > H140 Mechanics
Divisions:College of Science > School of Mathematics and Physics
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ID Code:18235
Deposited On:07 Aug 2015 12:28

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