Characterization of enhanced interfacial bonding between epoxy and plasma functionalized carbon nanotube films

The interfacial bonding between carbon nanotube (CNT) films and epoxy is usually fairly weak for high quality composites and difficult to be measured experimentally. In this study, the interfacial bonding strength between a CNT film and epoxy is measured using a peeling test. The CNT/epoxy interfacial bonding strength is altered by surface functionalization of the CNT film using atmospheric pressure helium/oxygen plasma. Furthermore, composites with the control and the modified CNT film impregnated in epoxy are manufactured, and their mechanical properties including peeling strengths and tensile strengths are improved remarkably due to enhanced CNT/epoxy bonding after plasma functionalization. The peeling strength between the CNT film and epoxy is increased by 156.6% and so is the fracture energy. The tensile strength of the functionalized CNT film/epoxy composites is 74.4% higher than that with original CNT film. The effect of the treatment time (0.1, 0.2 and 0.3s) is assessed by surface chemical and physical analyses, showing an improvement in the amount of oxygen-containing functional groups on CNT surface, and better dispersion of the CNTs in ethanol with increased treatment time. This benefits the wetting and infiltration into CNTs by epoxy to obtain a stronger interfacial bonding.