Mechanical behaviors and molecular deformation mechanisms of polymers under high speed shock compression: A molecular dynamics simulation study

Molecular dynamics (MD) simulations based on a united atom (UA) approach are performed to analyze the mechanical behaviors of polyethylene (PE) under high speed shock compression. With shock loads in a wide range from 0.3 km/s to 2 km/s, the behaviors of shock wave propagations in the polymer are presented. It is found that shock front thickness decreases as the shock load increases and even approaches to zero when the shock load reaches 2 km/s. Hugoniot curves in u(s)-u(p) and P-u(p) are presented, which agree qualitatively with the experimental results. In addition, the molecular morphological evolution is analyzed by the statistical method, which indicates that the major molecular deformation mechanism is bending instead of torsion. More evidences show that how internal mechanism associated with distributions of bond lengths, bond angles, dihedral angles and normalized mean-square radii of gyration. (C) 2016 Elsevier Ltd. All rights reserved.