On recycled carbon fibre composites manufactured through a liquid composite moulding process

Abstract

The recovery of carbon fibres from waste and end-of-life carbon fibre reinforced plastic materials is both economically lucrative and environmentally necessary. Here, we characterise the physical and mechanical properties of recycled carbon fibre reinforced plastics (rCFRPs) composed of random and oriented non-woven recycled carbon fibre mats that were impregnated with liquid epoxy matrices using a vacuum-infusion set-up. The low areal density and poor compactability of the non-woven mats implied that press-moulding upon impregnation was essential to control laminate thickness and improve fibre content; this may limit the applications of the resulting rCFRPs. Moreover, the press consolidation process is thought to degrade fibre length, and is a likely cause for the lower-than-expected tensile properties of the rCFRPs. Expectedly, the oriented rCFRPs exhibited better tensile and compressive properties than the random rCFRPs. Notably, while the tensile strength of the rCFRPs was only up to 2.5 times better than the matrix, the tensile modulus was 4–10 times enhanced. Through a comparative literature survey, we found that the liquid composite moulded rCFRPs were outperformed by rCFRPs fabricated through other manufacturing processes (e.g. prepregging), particularly those employing high compaction pressures, and utilising long fibres recovered through pyrolysis and chemical processes, rather than the fluidised-bed process.