Coefficients of thermal expansion of carbon nanotube-reinforced polyimide nanocomposites: A micromechanical analysis

Abstract

In this work, a unit cell-based micromechanical model with a proper representative volume element is proposed to evaluate the coefficients of thermal expansion of carbon nanotube-reinforced polyimide nanocomposites. The model takes an interphase between carbon nanotube and polyimide matrix into account which characterizes the non-bonded van der Waals interaction between two phases. The effects of some important parameters on the coefficients of thermal expansion such as thickness and adhesion exponent of interphase, temperature deviation as well as volume fraction, diameter and waviness of carbon nanotubes are investigated in detail. It is found that the interphase plays a critical role in determining the coefficients of thermal expansion and should be incorporated into the modeling of nanocomposite. According to the obtained results, there exists a specific value for carbon nanotube diameter beyond which further increasing in carbon nanotube diameter does not affect the coefficients of thermal expansion of nanocomposite. Also, the results reveal that the carbon nanotube waviness has a significant influence on the coefficients of thermal expansion of the nanocomposite. The results of the present model are compared with those of finite element method and a very good agreement is pointed out.