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

TLDR

The study examined multiwalled carbon nanotubes as mechanical reinforcement agents in polyvinyl alcohol and poly(9‑vinyl carbazole). Crystal growth induced by the nanotubes is thought to enhance matrix‑nanotube stress transfer. Nanotube addition increased Young’s modulus and hardness (up to 2.8× and 2.0×) and promoted PVA crystallization, with microscopy revealing strong interfacial bonding that caused polymer fracture rather than interface failure.

Abstract

In this work, multiwalled 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.