Micromechanics-Based Thermoelastic Analysis of Polyimide Nanocomposites Containing 3D Randomly Oriented Carbon Nanotubes

Abstract

The thermoelastic response of polyimide nanocomposites reinforced with randomly oriented carbon nanotubes (CNTs) is analyzed. For this purpose, a unit cell micromechanics model together with a proper representative volume element is employed. The interphase region created due to the non-bonded interaction between the CNT and surrounding polyimide matrix is taken into account in the modeling of nanocomposite. The effects of various parameters such as alignment and random orientation of CNTs into polyimide matrix, volume fraction and diameter of CNTs, size, adhesion exponent and material properties of the interphase region on the coefficient of thermal expansion (CTE) of polyimide nanocomposite are investigated. The results reveal that in the presence of interphase, the CTE nonlinearly increases with the reduction of CNT diameter, whereas without considering interphase, the change of diameter does not affect the thermoelastic properties of polyimide nanocomposite. Also, it is found that the CTEs of nanocomposite with interphase are higher than those of nanocomposite without interphase. Additionally, it is shown that the CTE of polyimide nanocomposite containing randomly oriented CNTs rises with increasing thickness, CTE and stiffness of interphase. The results of the presented model are in very good agreement with experimental data.