SI-04

(Oral presentation, session Smart Industry, 14.50 - 15.10 hrs)

To reduce weight and limit fuel consumption a growing interest of continuous fibre reinforced thermoplastic composites in aerospace, automotive and other industries can be seen. This leads to larger waste volumes (±€100 million till 2024) and recycling of this valuable material is required for environmental, economic and legislative reasons. One of the benefits of thermoplastic composites, in comparison to thermoset equivalents, is the possibility of recycling. However a high quality recycling route has been limited and current waste is disposed. This study focusses on cost-effective recycling of post-industrial thermoplastic composite waste into high-end applications at minimum environmental impact. The aim is to obtain mechanical properties close to the ones of original continuous fibre reinforced composites. Both low-end and high-end material types, various waste geometries and consolidation levels are included. A micro-mechanical model based on, among others, Kelly-Tyson enables the prediction of properties and the definition of required fibre lengths. This fibre length will determine the flake size for the comminution process. Material is shredded to flakes, thereafter simultaneously heated and mixed at low shear by a specially developed machine. After extrusion the charge is compression moulded into a plate or part. Samples are cut and subjected to bending tests to obtain flexural strength and stiffness, which are compared to analytically predicted properties. Micrographic analysis provides information about the void level and degree of mixing. Results show a robust process with properties enabling structural high-end applications. Two demonstrators are made. A safety shoe nose cap shows the opportunities for commodity materials in structural and critical parts. In the second demonstrator, high-end aerospace waste of a wing is recycled into parts for the same wing, proving the application into high-end applications. The design is not only more cost-effective and results in a lower environmental impact, but also shows a weight reduction.