Sviluppo di architetture tessili innovative a base di base di fibre di carbonio da riciclo per il settore dei materiali compositi

The increasing use of carbon fibre-reinforced plastic composite materials in several industrial applications concerning, for instance, transportation, construction and luxury sport equipment has led to an increase of waste generated, which is mainly incinerated or landfilled, causing significant environmental issues. The main reason lies in the inability to effectively utilise recycled carbon fibres that currently may only be used for the production of second-quality materials such as non-woven fabrics and injection moulded composites which possess low mechanical properties. As yarns are characterised by high fibre orientation and good compactness, they can be exploited to manufacture more oriented reinforcements, potentially enhancing the performance of final composite materials. Therefore, spinning could represent a way to expand the use of recycled carbon fibre to more structural components. In such a context, this Ph.D. project aims at developing an innovative spinning process to obtain yarns with repeatable physical, thermal and mechanical properties suitable for the production of carbon fibre-reinforced plastic composites for structural applications. To address this goal, a six-stage approach was followed. The achieved results show several pieces of evidence. First, recycled carbon fibres from manufacturing scraps may be handled by the proposed innovative spinning process, but they require to be blended with a thermoplastic fibre. Second, manufactured hybrid yarns have good tensile properties and good amount of recycled carbon fibre, although the different steps composing the proposed innovative spinning process reduce the theoretical amount inserted; therefore, they could be adopted for the fabrication of good-quality composite materials. CFRPs consisting of hybrid yarns produced with 70% recycled carbon fibres appear to be the most promising from a mechanical perspective. Third, the sustainability of the innovative spinning process has been analysed. Eventually, it is worth noting that this thesis has both theoretical and practical implications. On the one side, it improves the knowledge about the relationship between composite materials and circular economy by expanding the knowledge about spinning of carbon fibres waste from manufacturing scraps and providing future research directions in the field of fibre-reinforced plastic composite materials recycling technologies. On the other side, it offers a strong practical enrichment to the composite material industry by bringing important economic savings to companies, which may reduce both their raw materials purchase costs and waste disposal costs. Furthermore, the outcomes lead to a significant reduction in environmental impact, since the recycling of carbon fibres from manufacturing scraps allows the reduction of the use of virgin raw material and pollution due to incineration and landfill, as well as the recovery of the energy embodied in carbon fibres during their production.