Effects of carbon nanotube (CNT) geometries on the dispersion characterizations and adhesion properties of CNT reinforced epoxy composites

Carbon nanotubes (CNTs) are widely added into polymeric materials as additives to improve the mechanical properties of the composites. The great variances of CNTs in geometries including different diameters and lengths may inevitably result in extensive differences on material properties and reinforcing efficiencies in CNT reinforced epoxy composites . This paper investigated the dispersion characterizations and adhesion properties of CNT reinforced epoxy composites with different CNT geometries including three different CNT diameters and two different lengths by particle size analysis , single lap shear (SLS) tests, transmission and scanning electron microscopy (TEM and SEM). The experimental results showed that CNTs with larger diameter (50–100 nm) had a greater ability to achieve more uniform dispersion which further led to better adhesion properties. Although CNT length did not have an evident effect on the CNT dispersion, epoxy composites reinforced by normal-length CNTs (5–20 µm) had higher lap shear strength and toughness than those by shorter CNTs (0.5–2 µm).