Environmental assessment of a spinning process for the production of ring-spun hybrid yarns from recycled carbon fiber: A cradle-to-gate approach

The study of sustainable remanufacturing processes using recycled carbon fiber to enhance its applicability in high-performance materials is a key research direction. To this end, their environmental performance should be assessed. Here, an attributional life cycle assessment combined with environmental life cycle costing is performed for an innovative spinning process recently developed for the production of ring-spun hybrid yarns suitable for manufacturing reinforcements for good-quality polymer composites. Results indicate that the process cumulatively affects approximately 65.4% of the total environmental impact regarding climate change, use of fossils, and use of minerals and metals. The preparing and carding phase predominantly contributes to nearly all environmental impact categories. Greenhouse gas emissions from the process were quantified as 10.5 kg-CO2 eq/kg, significantly below those produced by virgin carbon fiber manufacturing (24-31 kg-CO2 eq/kg). Overall, considering the potential landfilling or incineration of waste used as input, the process brings environmental benefits ranging from 56% to 76%. A sensitivity analysis indicates that replacing manufacturing scraps with recycled carbon fiber from pyrolysis represents the input change with the highest environmental impacts, while thermoplastic fiber use does not significantly alter environmental performance. The study demonstrates that using recycled carbon fiber from manufacturing scraps is preferable to using recycled carbon fiber from pyrolysis when life-cycle impact is considered. The choice between polyamide and polyester should rely on the specific impact category to be addressed and the desired mechanical properties to be achieved in the final composite.