Enhanced properties of PAN-derived carbon fibres and resulting composites by active screen plasma surface functionalisation

Advanced active screen plasma (ASP) technology is used to modify polyacrylonitrile-derived carbon fibre (CF) surfaces using gas mixtures of N-2-H-2 and N-2-H-2-Ar. Unlike conventional plasma treatments, ASP treatment can reduce the structural disorder of CF surfaces and increase the surface crystallite size. Moreover, ASP treatment can lead to an increased single fibre tensile strength. This is mainly because the post-plasma nature of the ASP technology can effectively eliminate ion-bombardment-induced degradation while providing radicals necessary for surface modification. The addition of argon to the nitrogen-hydrogen gas mixture contributes to a more ordered graphitic structure on CF surfaces and further increases the single fibre tensile strength. The interfacial properties (interlaminar shear strength and flexural strength) of the resulting composites are improved.