Circular design for value-added remanufactured end-of-life composite material via additive manufacturing technology

In a context in which sustainability is going to assume an ever greater role in manufacturing and product development, recycling and reusing end-of-life materials appear as some of the major challenges in technology fields. Currently, a fair amount of methods and processes has been already developed, in order to give a second life to most of conventional materials, such as metals or thermoplastic polymers. Despite the increasing in glass fiber reinforced polymer composites structural applications (i. e. automotive, energy, constructions), it seems that their recycling and reusing are almost unexplored fields, due to the intrinsic multi-material nature. In fact, opposite to thermoplastic polymers, glass fiber reinforced composite materials are commonly composed of a thermoset matrix which cannot be melted and re-shaped after curing. How could composites be recycled, in a circular economy model? Is there a way for their remanufacturing, so as to obtain value-added and long-lasting products? Situated within “FiberEUse” European Project, the research’s main aim is to extend the life cycle of glass fiber reinforced polymer composites by using 3D Printing technology. Thus, it allows to produce environmentally sustainable objects with good mechanical properties and complex shapes, potentially suitable for a large range of application fields. At this purpose, a low-cost Liquid Deposition Modelling technology was used, allowing glass fiber mechanical recycling for Additive Re-manufacturing. More in details, end-of-life shredded composites were adopted as reinforcement of a photo- and thermo-curable material with an acrylate-base resin as matrix: the output can be properly 3d printed by extruding the liquid material before its in situ polymerisation. Primarily, the experimental work focused on two main aspects: the material characterization, with a remanufacturing process optimisation approach, and its application field analysis, for designing new value-added products. Regarding the first case, it was possible to better understand the way for obtaining the appropriate material composition and process settings, in order to achieve a satisfactory 3d printed outcome, as well as to unveil its mechanical and physical properties. Considering the second one, applications that could take advantages both from composites materials and additive manufacturing technology were investigated. Through samples design and, consequently, 3d printing realisation, the whole process has been validated: new way to reuse an end-of-life composite material was given by using Liquid Deposition Modelling, promoting the implementation of a circular economy. After process parameters setting, it was possible to perform self-standing 3d prints by modulating the polymerisation directly hardening the reinforced resin after the extrusion, overcoming the current concept of supports in additive manufacturing processes. Taking into account both the application field and the above-mentioned results, urban design could benefit from end-of-life composites 3d printing, giving new senso-aesthetic possibilities to designer figures. Considering both material properties and remanufacturing process, street furniture and amusement park structures will be realised directly in situ by a targeted and customised project, as soon as a future process scale-up can be managed.