Prediction of the elastic modulus of SWCNT/epoxy composite based on the micromechanics

Abstract

Abstract Due to their superior mechanical and physical properties, carbon nanotubes seem to hold a great promise as an ideal reinforcing material for composites of high strength and low density. In most of the experimental results up to date, however, only modest improvements in the strength and stiffness have been achieved by incorporating carbon nanotubes in polymers. In the present paper, the stiffening effect of carbon nanotubes is quantitatively investigated by micromechanics methods. The Mori-Tanaka effective field method has been adopted to calculate the effective elastic moduli of composites with aligned or randomly oriented straight nanotubes. The rule-of-mixtures is used to calculate the modulus of elasticity for nanocomposite. The results of micromechanics methods indicated that the CNTs are highly anisotropic, with Young's modulus in the tube direction two orders of magnitude higher than that normal to the tube. The results of micromechanics methods were compared by those obtained from the rule-of-mixtures and good agreement was also achieved when the efficiency parameter Φ = 1 and typical results were achieved with Φ = 0.25. To predict the mechanical properties of the composite materials, it is worth considering the conventional rule-of-mixtures using exact value of the efficiency parameter Φ. To predict the elastic modulus of nanocomposite reinforced by SWCNT using the conventional rule-of-mixtures, the exact value of the efficiency parameter Φ is equal to 0.25 when using nanotubes with chirality (8,3) for determination the elastic modulus of SWCNT. However, for zigzag orientation and chirality (8,0) the efficiency parameter Φ is equal to 1. The conventional rule-of-mixtures is a powerful tool and easy method compared to the micromechanics methods.