Reinforcing potential of carbon nanotubes in oriented polymer fibres

The potential of carbon nanotubes as reinforcing fibres in polymer composites is reviewed, with particular emphasis on oriented systems such as films and fibres. The introduction of nanofibres into such oriented polymer systems can mimic the structure of natural materials such as bone and tooth, creating 'designed' composite materials with additional levels of hierarchy. Issues relating to the manufacture of well dispersed composites are considered and their mechanical properties detailed. Despite the excellent properties of carbon nanotubes as a reinforcing phase, the properties of composites reported in the literature have to date been disappointing. However, recent work has demonstrated that the addition of small amounts of single wall nanotubes (SWNTs) can lead to extraordinary reinforcing effects in oriented polymer composites. Stress contributions of SWNTs to the composite strength of up to 90 GPa, very close to the theoretical strength of nanotubes, were found if these were well dispersed and oriented.