Correlation between interfacial molecular structure and mechanics in CNT/epoxy nano-composites

We study the effect of the molecular nature of the interface between an epoxy matrix and multi-walled carbon nanotubes (CNTs) on the mechanical properties of the resultant nano-composites, with emphasis on toughness A number of samples based on variously functionalized CNTs, namely, pristine, carboxylated, and aminated CNTs are examined, with different qualities of dispersion. Nano-composite toughness is found to increase with enhanced interfacial adhesion, an effect that is opposite to what is usually observed in traditional fiber-based composites The classical pull-out energy model is shown to effectively explain this result. It is thus possible to tune the toughness of a nano-composite by adjusting the molecular nature of its interface and the CNT characteristics, namely its strength and its length relative to its critical length. (C) 2009 Elsevier Ltd All rights reserved.