Considering semi-crystallinity in molecular simulations of mechanical polymer properties – using nanoindentation of polyethylene as an example

Susanne Fritz

FILK Freiberg Institute gGmbH, Meißner Ring 1-5, 09599 Freiberg, Germany.

DOI:

https://doi.org/10.7494/cmms.2021.1.0747

Abstract:

Molecular dynamic (MD) simulations have been used to investigate the response of semi-crystalline polymers in nanoindentation tests, using polyethylene (PE) as an example. To that purpose, semi-crystalline simulation boxes of linear PE with various chain lengths up to C2000 were created by homogeneous nucleation during the non-isothermal cooling of melts. The final crystallinity depended on the chain length and the cooling rate used and could be estimated using various parameters like density, fraction of bonds in trans conformation, and energy terms. The simulation boxes were transferred into surface models and subjected to nanoindentation tests using non equilibrium MD. This allowed the deformation behaviour of the material to be analysed directly. Strong dependencies on the crystallinity of the PE were found, which underlines the importance of considering crystallinity when investigating the mechanical properties of semi-crystalline polymers by means of simulations.

Cite as:

Fritz, S. (2021). Considering semi-crystallinity in molecular simulations of mechanical polymer properties – using nanoindentation of polyethylene as an example. Computer Methods in Materials Science, 21(1), 35–50. https://doi.org/10.7494/cmms.2021.1.0747

Article (PDF):

Keywords:

Molecular dynamic, Simulation, Polymer, Polyethylene, Semi-crystalline, Mechanical properties, Crystallization, Nanoindentation

References:

Abraham, M.J., Murtola, T., Schulz, R., Páll, S., Smith, J.C., Hess, B., & Lindahl, E. (2015). GROMACS: High performance molecular simulations through multi-level parallelism from laptops to supercomputers. SoftwareX, 1–2, 19–25.

Abu-Sharkh, B., & Hussein, I.A. (2002). MD simulation of the influence of branch content on collapse and conformation of LLDPE chains crystallizing from highly dilute solutions. Polymer, 43(23), 6333–6340.

Allen, M.P., & Tildesley, D.J. (1987). Computer Simulation of Liquids. Clarendon Press.

Anwar, M., & Schilling, T. (2015). Crystallization of polyethylene: A molecular dynamics simulation study of the nucleation and growth mechanisms. Polymer, 76, 307–312.

Berendsen, H.J.C., Postma, J.P.M., Gunsteren, W.F. van, DiNola, A., & Haak, J.R. (1984). Molecular dynamics with coupling to an external bath. The Journal of Chemical Physics, 81(8), 3684–3690.

Berendsen, H.J.C., Spoel, D. van der, & Drunen van, R. (1995). GROMACS: A message-passing parallel molecular dynamics implementation. Computer Physics Communications, 91(1–3), 43–56.

Bussi, G., Donadio, D., & Parrinello, M. (2007). Canonical sampling through velocity rescaling. The Journal of Chemical Physics, 126(1), 014101.

Christöfl, P., Czibula, C., Berer, M., Oreski, G., Teichert, C., & Pinter, G. (2021). Comprehensive investigation of the viscoelastic properties of PMMA by nanoindentation. Polymer Testing, 93, 106978.

Daura, X., Mark, A.E., & Gunsteren, W.F.J. van (1998). Parametrization of Aliphatic CHn United Atoms of GROMOS96 Force Field. Journal of Computational Chemistry, 19(5), 535–547.

Doran, M., & Choi, P. (2001). Molecular dynamics studies of the effects of branching characteristics on the crystalline structure of polyethylene. The Journal of Chemical Physics, 115(6), 2827–2830.

Fox, T.G., & Flory, P.J. (1954). The glass temperature and related properties of polystyrene. Influence of molecular weight. Journal of Polymer Science, 14(75), 315–319.

Frenkel, D., & Smit, B. (2001). Understanding molecular simulation: from algorithms to applications (2nd ed.). Academic Press.

Gao, R., He, X., Shao, Y., Hu, Y., Zhang, H., Liu, Z., & Liu. B. (2016). Effects of Branch Content and Branch Length on Polyethylene Crystallization: Molecular Dynamics Simulation. Macromolecular Theory and Simulation, 25(3), 303–311.

Gibson, R.F. (2014). A review of recent research on nanoindentation of polymer composites and their constituents. Composites Science and Technology, 105, 51–65.

Monasse, B., Queyroy, S., & Lhost, O. (2008). Molecular Dynamics prediction of elastic and plastic deformation of semi-crystalline polyethylene. International Journal of Material Forming, 1(supplement issue 1), 1111–114.

Moyassari, A., Gkourmpis, T., Hedenqvist, M.S., & Gedde, U.W. (2019a). Molecular Dynamics Simulations of Short-Chain Branched Bimodal Polyethylene: Topological Characteristics and Mechanical Behavior. Macromolecules, 52(3), 807–818.

Moyassari, A., Gkourmpis, T., Hedenqvist, M.S., & Gedde, U.W. (2019b). Molecular dynamics simulation of linear polyethylene blends: Effect of molar mass bimodality on topological characteristics and mechanical behavior. Polymer, 161, 139–150.

Oostenbrink, C., Villa, A., Mark, A.E., & van Gunsteren, W.F. (2004). A Biomolecular Force Field Based on the Free Enthalpy of Hydration and Solvation: The GROMOS Force-Field Parameter Sets 53A5 and 53A6. Journal of Computational Chemistry, 25(13), 1656–1676.

Páll, S., & Hess, B. (2013). A flexible algorithm for calculation pair interactions on SIMD architectures. Computer Physics Communications, 184(12), 2641–2650.

Peng, C., & Zeng, F. (2017). A molecular simulation study to the deformation behavior and the size effect of polyethylene during nanoindentation. Computational Materials Science, 137, 225–232.

Poly(ethene) (Polyethylene) (2017). The Essential Chemical Industry, https://www.essentialchemicalindustry.org/polymers/polyethene.html.

Ramos, J., & Martínez-Salazar, J. (2011). Computer Modeling of the Crystallization Process of Single-Chain Ethylene/1-Hexene Copolymers from Dilute Solutions. Journal of Polymer Science Part B: Polymer Physics, 49(6), 421–430.

Ramos, J., Vega, J.F., & Martínez-Salazar, J. (2018). Predicting experimental results for polyethylene by computer simulation. European Polymer Journal, 99, 298–331.

Rozanski, A., & Galeski, A. (2013). Plastic yielding of semi-crystalline polymers affected by amorphous phase. International Journal of Plasticity, 41, 14–29.

Ruestes, C.J., Alhafez, I.A., & Urbassek, H.M. (2017). Atomistic Studies of Nanoindentation – A Review of Recent Advances. Crystals, 7(10), 293.

Sanmartín, S., Ramos, J., & Martínez-Salazar, J. (2012). Following the Crystallization Process of Polyethylene Single Chain by Molecular Dynamics: The Role of Lateral Chain Defects. Macromolecular Symposia, 312(1), 97–107.

Sanmartín, S., Ramos, J., Vega, J.F., & Martínez-Salazar, J. (2014). Strong influence of branching on the early stage of nucleation and crystal formation of fast cooled ultralong n-alkanes as revealed by computer simulation. European Polymer Journal, 50, 190–199.

Schuler, L.D., Daura, X., & Gunsteren, W.F.J. van (2001). An Improved GROMOS96 Force Field for Aliphatic Hydrocarbons in the Condensed Phase. Journal of Computational Chemistry, 22(11), 1205–1218.

VanLandingham, M.R., Villarrubia, J.S., Guthrie, W.F., & Meyers, G.F. (2001). Nanoindentation of Polymers: An Overview. Macromolecular Symposia, 167(1), 15–43.

Verho, T., Paajanen, A., Vaari, J., & Laukkanen, A. (2018). Crystal Growth in Polyethylene by Molecular Dynamics: The Crystal Edge and Lamellar Thickness. Macromolecules, 51(13), 4865–4873.

Voyiadjis, G.Z., & Yaghoobi, M. (2017). Review of Nanoindentation Size Effect: Experiments and Atomistic Simulation. Crystals, 7(10), 321.

Wang, J., Zhao, L., Song, M., Hu, F., & He, X. (2021). Molecular dynamics simulation for polyethylene crystallization: the effect of long chain branches. Polyolefins Journal.

Xu, M., Huang, G., Feng, S., McShane, G.J., & Stronge, W.J. (2016). Static and Dynamic Properties of Semi-Crystalline Polyethylene. Polymers, 8(4), 77.

Yashiro, K., Furuta, A., & Tomita, Y. (2006). Nanoindentation on crystal/amorphous polyethylene: Molecular dynamics study. Computational Materials Science, 38(1), 136–143.

Yeh, I.-C., Andzelm, J.W., & Rutledge, G.C. (2015). Mechanical and Structural Characterization of Semi-crystalline Polyethylene under Tensile Deformation by Molecular Dynamics Simulations. Macromolecules, 48(12), 4228–4239.

Yeh, I.-C., Lenhart, J.L., Rutledge, G.C., & Andzelm, J.W. (2017). Molecular Dynamics Simulation of the Effects of Layer Thickness and Chain Tilt on Tensile Deformation Mechanisms of Semi-crystalline Polyethylene. Macromolecules, 50(4), 1700–1712.

Zhang, J., Wang, Z., Yan, Y., & Sun, T. (2016). Concise Review: Recent Advances in Molecular Dynamics Simulation of Nanomachining of Metals. Current Nanoscience, 12(6), 653–665.