Highly aligned polyacrylonitrile-based nano-scale carbon fibres with homogeneous structure and desirable properties

Continuous polyacrylonitrile-based nano-fibres are produced by an electrospinning approach and then converted to nano-scale carbon fibres (n-CFs) with a homogeneous structure by introducing multi-step hot-stretching in this paper. The processed n-CFs are highly aligned and partially graphitic, yet obtained at a temperature range normally associated with carbonization, and show remarkably uniform structures and a quite smooth surface with a mean roughness of 0.249 nm. The electrical conductivity of the n-CFs reaches 15.5 S/cm along the fibre direction. Tensile tests demonstrate an enhancement of 21% and 60% in tensile strength and Young's modulus, respectively, of polyetherimide composite membranes containing 1 wt% n-CFs treated with multi-step hot-stretching, which is more remarkable reinforcing effect compared to the multi-walled carbon nanotubes. It is believed that the developed approach, electrospinning and multi-step hot-stretching technique, can be a practicable means for the fabrication of continuous n-CF reinforcement with high structural integrity and desirable properties.