Thermal Conductivity of Natural Rubber Using Molecular Dynamics Simulation

Area of Science:

• Materials Science
• Polymer Physics
• Computational Chemistry

Background:

• Natural rubber is a vital elastomer with applications requiring specific thermal properties.
• Understanding thermal conductivity is crucial for designing and utilizing natural rubber in various engineering applications.
• Classic molecular dynamics simulations offer a computational approach to investigate material properties at the molecular level.

Purpose of the Study:

• To investigate the thermal conductivity of natural rubber using molecular dynamics simulations.
• To determine the influence of simulation parameters, specifically the time step, on the accuracy of thermal conductivity results.
• To explore the anisotropic thermal conductivity of a model natural rubber with aligned molecular chains.

Main Methods:

• Classic molecular dynamics (MD) simulations were employed.
• The adaptive intermolecular reactive empirical bond order (AIREBO) potential was utilized for interatomic interactions.
• Green-Kubo formalism was applied to calculate thermal conductivity.
• Simulations were performed with varying time steps to assess convergence.

Main Results:

• Thermal conductivity was found to be highly sensitive to the time step in the simulations.
• A converged thermal conductivity value of 0.35 W/mK was obtained using a time step of 0.1 fs.
• For a model with straight molecular chains, thermal conductivity parallel to the chains was 1.71 W/mK.
• An anisotropy ratio of 2.67 (2Kz/(Kx + Ky)) was observed in the aligned chain model.

Conclusions:

• The choice of time step is critical for accurate thermal conductivity calculations in natural rubber via MD simulations.
• Natural rubber exhibits anisotropic thermal conductivity, particularly when molecular chains are aligned.
• The simulation methodology provides valuable insights into the thermal transport mechanisms in natural rubber.