Amino functionalisation of carbon nanotube webs for achieving high structural performance of multifunctional nano-enhanced hierarchical composites

Carbon nanotube (CNT) assemblies such as webs (CNTw) are functionalised in gas-phase reaction in order to chemically modify the CNT surface without disturbing its overall structure. It is proposed for the first time to amino functionalise CNT assemblies in gas-phase to promote bonding with epoxy matrices. Two different diamines are selected, aliphatic (ethylenediamine, EDA) and aromatic (1,5-diaminonaphtalene, DAN). The presence of the diamine molecules is confirmed by infrared spectroscopy and the amount incorporated is estimated by thermogravimetric analysis. Its influence on fracture toughness is studied using a Mode I interlaminar fracture toughness. The functionalisation of the CNTw with EDA results in an increase in GIC of 20 % while the same procedure with DAN gives no improvement. This different observed behaviour is due to the different temperature required to activate the diamines to react with the epoxy rings of the epoxy system, as seen by differential scanning calorimetry. © 2017 International Committee on Composite Materials. All rights reserved.