Decreasing the environmental impact of carbon fibre production via microwave carbonisation enabled by self-assembled nanostructured coatings

Abstract

Abstract The use of carbon fibre (CF) based composites is of growing global importance due to their applications in high end sectors such aerospace, automotive, construction, sports and leisure amongst others. It is forecast that composites will reach a global market value of $131.6 bn by 2024. However, their current high production cost, high carbon footprint and reduced production capability, limits their use to high performance and luxury applications. Approximately 50 % of the total cost of CF production is due to the thermal conversion of PAN precursor fibre (PF) to CF as it involves the use of high energy consumption and low heating efficiency large furnaces. Looking at this scenario we propose in the present study to use microwave (MW) heating to convert PF to CF. This is scientifically and technologically challenging since PF does not absorb microwave energy. Here, for the first time we show how carbonisation temperatures of >1000 ºC can be reached in a matter of seconds through the use of a novel microwave (MW) susceptor nanocoating methodology developed via a Layer-by-layer assembly of multiwall carbon nanotubes (MWCNTs) on the PF surface. Remarkably, these CFs can be produced in an inexpensive domestic microwave and exhibit mechanical performance equivalent to CF produced using conventional heating. Additionally, we provide a life cycle and environmental impact analysis which shows that MW heating reduces the energy demand and environmental impact of lignin-based CF production by up to 66.8% and 69.5%, respectively.