Understanding the mechanical behavior of polymers using molecular dynamics simulation

Atomistic simulations, also known as molecular dynamics simulations, can give significant insights on the relationships between structure and properties, which can be used for the creation of new polymer-based materials. Molecular dynamics simulation is mainly used to analyze atomic and molecular movements within a system. This simulation mimics real life atomic and molecular interactions by assuming a given potential energy function. This energy function enables calculating the force experienced by any atom with respect to the position of other atoms. The trajectories of these atoms are determined using Newton’s equations of motion. The values obtained from the atomic force and motion can be used to estimate the mechanical properties of the system. In this study, mechanical responses of polymers under various loading scenarios were captured using molecular dynamics simulation for in-depth understanding of the structure properties relationships. A classical molecular dynamics simulation software, large-scale atomic/molecular massively parallel simulator (LAMMPS) was used for the modeling purpose. The MD simulation framework used in the study was validated using the experimental data obtained from the literature. According to the MD simulation findings, Young’s modulus and yield strength of polyethylene depend on the molecular weight. Furthermore, the simulation was able to capture the temperature- and pressure-dependent mechanical responses of polyethylene. The results show a general increase in Young’s modulus and yield strength with increase in molecular weight under various temperature- and pressure-dependent tensile loading scenarios