Development of high performance recycled carbon fibre composites with an advanced hydrodynamic fibre alignment process

Abstract

Carbon fibre composites have great potential for vehicle lightweighting but the high cost and environmental impact of their production tends to largely undermine the advantages in non-aerospace applications. Recycled fibre has the potential to significantly reduce both cost and environmental impact but has yet it has not been widely accepted by the composites industry due to reduced mechanical performance in components as well as the difficulties in handling and processing caused by the fluffy discontinuous form which is quite unlike any current material formats which suit existing processing methods. The developed alignment process allows discontinuous random recycled carbon fibre to be processed into tapes with a highly aligned orientation distribution. This allows composites with high fibre content to be manufactured at lower moulding pressures with the added benefit of keeping fibre length degradation to a minimum. To evaluate the effects of process factors on fibre orientation, a two-level full factorial experimental plan was designed. This represents the first time a systematic study of input parameters on final part performance has been published in the open literature. With further improvements to the process, it is shown that it is possible to manufacture a composite achieving high fibre volume content (46%) under 7 bar moulding pressure in an autoclave, exhibiting competitive mechanical properties with almost 100 GPa tensile modulus and over 800 MPa tensile strength.