Nanomechanics model for properties of carbon nanotubes under a thermal environment

This paper proposes a modified molecular mechanics model in which the covalent bond is treated as a beam element, and a theoretical prediction of the thermal environment effect on the elastic properties of single-walled carbon nanotubes (SWCNTs) is reported. The influence of the temperature on Young's modulus of both armchair and zigzag SWCNTs is investigated. The study shows that the moduli decrease with the increase in temperature, but Poisson's ratio is not dependent on the temperature. The temperature-dependent Young's modulus increases with the increase in tube diameter. According to the principle of elasticity theory and energy consistent theory, a temperature-dependent continuum shell model of strain energy is also established. It is found that the deviation between the potential energy of carbon nanotubes and the strain energy of a continuum shell is significantly reduced based on the molecular mechanics model proposed in this study.