Morphological and mechanical properties of carbon-nanotube-reinforced semicrystalline and amorphous polymer composites

In this work, multimalled carbon nanotubes were investigated as potential mechanical reinforcement agents in two. hosts, polyvinyl alcohol (PVA) and poly(9-vinyl carbazole) (PVK). It was found that, by adding various concentrations of nanotubes, both Young's modulus and hardness increased by factors of 1.8 and 1.6 at 1 wt% in PVA and 2.8 and 2.0 at 8 wt% in,PVK, in reasonable agreement with the Halpin-Tsai theory. Furthermore, the presence of the nanotubes was found to nucleate crystallization of the PVA. This crystal growth is thought to enhance matrix-nanotube stress transfer. In addition, microscopy studies suggest extremely strong interfacial bonding in the PVA-based composite. This is manifested by the fracture of the polymer rather that the polymer-nanotube interface. (C) 2002 American Institute of Physics. [DOI:10.1063/1.1533118].