Visualization of conformational changes of linear short-chain polyethylenes under shear and elongational flows

We have performed nonequilibrium molecular dynamic simulations of the linear short-chain polyethylene liquids C24H50, C50H102, C78H158, and C128H258 under homogenous shear and elongational flows. We present visualizations of the molecular structure of each of the four liquids under shear and elongation, and compare them with their equilibrium static structures. These graphics provide a structural understanding of the various statistical measures that have been used in the literature to characterize the change in chain conformation as a function of strain rate and chain length. Moreover, these graphics allow a visualization of the inherent chain dynamics and orientation induced by shear and elongational flows. We discuss the molecular-level mechanisms apparent in the graphics. (c) 2007 Elsevier Inc. All rights reserved.