Effects of CNT Diameter on the Uniaxial Stress-Strain Behavior of CNT/Epoxy Composites

The present work studies the effects of the diameter of carbon nanotube (CNT) as well as CNT weight fraction on the uniaxial stress-strain behavior, stiffness, and strength of CNT-reinforced epoxy-matrix composites. The experimental results show that average Young's moduli of 5wt%-CNT/epoxy composites with a CNT diameter D < 20 nm and D = 40 similar to 60 nm are 4.56 GPa and 4.36 GPa, and the average tensile strengths are 52.89 MPa and 46.80 MPa, respectively, which corresponds to a percentage increase of 61.1%, 54.1%, 106%, and 82.3%, respectively. Two micromechanics models are employed and the predicted Young's moduli are benchmarked with the experimental data of MWCNT-reinforced epoxy-matrix composites. Copyright (C) 2008 N.Yu and Y.W. Chang.