Recent Molecular Dynamics Simulations

Molecular dynamics simulations were recently run to get amorphous structure throughout deformation. An initial polyethylene structure of 20 chains with 400 monomers per chain was generated using an FCC lattice and a self-avoiding random walk, according to Tschopp, et al. The structure was equilibrated at 500K and then cooled to 375 (below the melting temperature). Deformation was performed at constant strain rate of was performed to give a total strain of 1.0.

Amorphous PE deformed at strain rate

Video created using VMD

Further simulations are being performed on semi-crystalline structure. The semi-crystalline structure is generated by slow cooling from 500K to 425K, equilibrating. Then uniaxial deformation is performed to generate an oriented melt at strain rate and the structure is quenched to 375K. After equilibration allowing crystallization at 375K the same deformation as was performed on the amorphous structure will be performed.

References:

  • Hossain, D., Tschopp, M. a., Ward, D. K., Bouvard, J. L., Wang, P., & Horstemeyer, M. F. (2010). Molecular dynamics simulations of deformation mechanisms of amorphous polyethylene. Polymer, 51(25), 6071–6083.
  • Ko, M. J., Waheed, N., Lavine, M. S., & Rutledge, G. C. (2004). Characterization of polyethylene crystallization from an oriented melt by molecular dynamics simulation. The Journal of Chemical Physics, 121(6), 2823–32.