Carbon nanotubes (CNTs) have potential for a wide range of applications in the composite field. Their large aspect ratio, excellent conductivity, and ultra-high mechanical and thermal properties make them an outstanding candidate for multifunctional nanofillers in combination with carbon fibre reinforced plastics (CFRP). Thanks to their intrinsic multifunctionality, CNTs have demonstrated to be able to provide polymer composites with electrical properties, mechanical properties, sensing ability, self-healing properties, thermal conductivity and improved thermal stability, etc. A combination of these properties can be tailored by engineering these materials from the nano to mm level into hierarchical structures in order to fulfill desired applications.

Damage sensing in structural composites is one of the important possible applications for CNT/polymer composites. It is demonstrated that conducting carbon nanotube networks formed in a thermosetting polymer matrix can be used as highly sensitive sensors for detecting the onset, nature, and evolution of damage in advanced composites. The internal damage accumulation can be monitored in situ using electrical measurements. These results demonstrate promises for the evaluation of self-healing approaches for polymer composites and the development of enhanced life prediction methodologies.