Molecular Dynamics Simulations of Thermal and Mechanical Properties of Carbon Nanotubes — 30p — Lida Najmi

Due to their enhanced properties, carbon nanotubes (CNTs) are increasingly used in various industrial sectors. Specifically, the thermal conductivity of these materials is affected by heat transfer mechanisms across multiple scales, leading to a complex relationship between the effective response and the microscopic characteristics of the material. Due to their high thermal conductivity, CNTs have applications in various fields including electronics, materials science, and thermal management. They
are incorporated into composites, films, and other materials to enhance their thermal performance. In this topic, the thermal properties of single-walled carbon nanotubes (SWNTs) are investigated using molecular dynamics (MD) simulation. The effects of the chirality, diameter, and length of SWNTs on the thermal properties were studied using the reverse non-equilibrium molecular dynamics (RNEMD) method and the carbon-carbon based Tersoff interatomic potential based on the Large-scaled
Atomic/Molecular Massively Parallel Simulator (LAMMPS). The SWNTs studied have tube lengths of 5, 10, 15 and 20 nm, respectively. The thermal conductivity follows a L B law. The exponent B is insensitive to the chiral angle of the CNT; B at room temperature is about 0.89 and 0.69 for zigzag and armchair CNTs, respectively. Although thermal conductivity increases with increasing the chiral angle, and armchair SWNTs have higher thermal conductivity than zigzag CNTs, the effect of chirality on the thermal conductivity for longer CNTs decreases. Therefore, for longer length SWNTs, the thermal conductivity of the zigzag is greater than that of the armchair ones. Through research on SWNTs of different diameters, it was found that at the same chiral angle, the thermal conductivity of SWNTs decreases with the increase in diameter, while SWNTs with greater chiral angles exhibit higher thermal conductivity than those of the same diameter. The thermal conductivity follows a D -B trend, and the exponent B is insensitive to the chiral angle of the CNTs; the B of zigzag and armchair CNTs at room temperature are about 0.43 and 0.26, respectively. In addition, the thermal resistance at the CNT’s interfaces was studied as a function of the nanotube spacing, overlap, and length. The simulation results were compared with the experiments and simulation results from the literature which are in agreement. The presented approach can be applied to study the properties of other advanced materials.

Keywords: Carbon Nanotubes (CNTs), Single-walled carbon nanotubes (SWNTs), Chirality, Aspect ratio, Topological parameter, Molecular dynamics (MD) simulations

South Dakota State University
Zhong Hu