Thermomechanical investigation of unidirectional carbon fiber-polymer hybrid composites containing CNTs

In this research, the thermoelastic response of unidirectional carbon fiber (CF)-reinforced polymer hybrid composites containing carbon nanotubes (CNTs) are analyzed using a physics-based hierarchical micromechanical modeling approach. The developed model consists of a unit cell-based scheme along with the Eshelby method which can consider random orientation, random distribution, directional behavior, non-straight shape of CNTs and interphase region generated due to the non-bonded van der Waals interaction between a CNT and the polymer matrix. The predictions are compared with the experimental data available in the literature and a quite good agreement is pointed out for the fibrous polymer composite, CNT-polymer nanocomposite and fiber/CNT-polymer hybrid composite systems. The influences of several factors, including volume fraction, aspect ratio, off-axis angle and arrangement type of CFs as well as CNT volume fraction on the thermoelastic behavior of CF/CNT-polymer hybrid composites are examined in detail. The results indicate that the transverse CTE of a unidirectional CF-reinforced composite is significantly improved due to the addition of CNTs, while the hybrid composite CTE in the longitudinal direction is negligibly affected by the CNTs. Also, it is found that the role of CNT in the hybrid composite thermoelastic behavior becomes more prominent as the CF aspect ratio decreases.