Abstract
This study is part of the NESSIE project, which aims to develop a composite material using recycled carbon fibres and a thermosetting resin for a nautical application. Every year, tens of thousands of tonnes of end-of-life carbon fibre-reinforced composite materials are produced by the aeronautics, automotive and energy industries. The recovery of carbon fibres, whose objective is to preserve all their initial properties, is theoretically possible thanks to thermal or chemical treatments. The processes currently used at prototype scale led to significant degradation of the fibres, such as loss of mechanical strength or modification of surface properties leading to a reduction in adhesion with the matrix. One of the main problems currently encountered in recycling is the loss of alignment of fibres during the process. Alignment is necessary for the reuse of recycled carbon fibres to provide controlled and sufficient mechanical reinforcement for a structural application. If realignment of recycled fibres is possible on an industrial scale in the next few years, a sliver of aligned virgin discontinuous carbon fibres represents the closest "theoretical" reinforcement that could be obtained after recycling and realignment. In the remainder of the study, the influence of the surface condition of the fibres after heat treatment, the alignment and the median length of the carbon fibres constituting a "theoretical" sliver were studied. The results allowed recommendations to be made on the quality of recycled carbon fibres eligible after thermal or chemical recycling for the development of a recycled carbon fibre yarn. These recommendations include maintaining fibre alignment and optimal fibre/matrix adhesion.