Abstract

Abstract

The content of this project is focused on the development of a process to reuse uncured A350 prepreg scrap obtained in production plants. The main aim is to reduce the current buy to fly ratio, which is the used raw material versus the material that will finally fly and, thus, to achieve clear benefits in terms of environmental aspects. The key properties of the new virgin material obtained after this reusing process have been evaluated in order to assess potential applications in aeronautical or other fields (e.g. automotive, sport, civil works…). Additionally, some aeronautical demonstrators or pilot cases with the reused material and process were produced. Regarding the key conclusions of this workt up to now: an effective process has been developed to reuse A350 uncured prepreg scrap, mainly mono-ply, based on chopping the prepreg to obtain a new virgin material, which will be used to produce a part by applying a compression molding process. Although the properties of the new raw material show high scatter, some of them stay close or even higher versus the reference (e.g. CAI). To end with, several aeronautical demonstrators with acceptable quality have been produced with the prepreg reuse process developed in this project (e.g. complex brackets, gaskets, manholes…).

Abstract

Abstract

Due to the great increase in the use of composite materials, there is a need to investigate and develop effective recovery, recycling, and reuse techniques. This technological challenge entails significant research efforts to solve the current problems to separate and reuse the components of composite materials. In this work, two alternatives have been studied to solve the environmental problems that the use of resins as a matrix of composite materials entails, since there is no sustainable recycling process after its useful life cycle. On the one hand, a thermomechanical reprocessing will be studied and on the other the viability of the chemical dissolution of the matrix. For both processes, the optimal conditions (temperature, time, solvent, and pressure) have been studied to allow reprocessing the material or dissolve the resin of the composite material to recover the fiber. Subsequently, for thermomechanical reprocessing, the technical feasibility of impregnating fibers during the reprocessing process in the hot plate press has been studied. And for chemical recycling, the feasibility that the recycled carbon fiber will be reused to make a new composite material.

Abstract

En este capítulo se describen las diferentes estrategias de reutilización que se pueden llevar a cabo con los materiales compuestos con matrices poliméricas una vez pasados por los centros de reciclaje actualmente disponibles a escala industrial. 

El trabajo describe cómo, dependiendo de la naturaleza tanto de las matrices como de las fibras de refuerzo, la reutilización de este tipo de fibras debe estar dirigida hacía un tipo de procesos u otros y cómo, mediante la variación de las tecnologías, es posible dar lugar a productos con una mayor o menor orientación de las fibras. De la misma manera, el capítulo analiza algunos de los procesos de fabricación de materiales compuestos, que pueden afectar a la longitud de las fibras y por lo tanto modificar las propiedades del material final. 

De esta forma, se describen las diferentes tecnologías actualmente disponibles y en proceso de desarrollo en España para poder dar una nueva vida a las fibras de carbono y de vidrio, orientadas a retener la mayor parte de su valor añadido y propiedades, como son: reutilización en materiales compuestos termoestables, reutilización como refuerzo en materiales compuestos termoplásticos, reprocesado de la fibra (estructuras de fibra tejidas o no tejidas), reciclado de fibras que todavía estén embebidas, reciclajes específicos según la naturaleza de la fibra. 

A lo largo del texto se van recogiendo algunos de los proyectos liderados por entidades españolas con mayor relevancia en el desarrollo de las diferentes tecnologías y, además, al final del mismo se remarcan esos mismos proyectos y otros más en los que se destaca el trabajo realizado por centros, universidades y empresas españolas en el campo de la reutilización y reciclaje de fibras de carbono y de vidrio.

Abstract

This chapter addresses two relevant challenges to enforce in a manufacturing plant where carbon fiber prepreg is used as raw material for the manufacture of aeronautical parts. The first challenge is the segregation of fresh production waste, where the resin is fresh and has a big potential for being used as material for other applications. This chapter described a proposal for the collection of this highly valuable material in a pilot plant where aircraft stabilizers are manufactured. This second challenge addresses solutions for the reprocessing of waste material discarded during the manufacturing of carbon parts. Hereafter is described the preparation of new materials or by-products, which can be reincorporated into the production system of other composite material parts.

Abstract

Spain, holding a prominent position in Europe's composites industry and notably in aviation composites, faces significant waste management challenges within its 500-strong composite company sector. As it shifts towards the Circular Economy to enhance competitiveness and resource efficiency, Spain adheres to the EU's waste hierarchy, emphasizing the critical need for waste minimization and the reuse of materials. This transition is particularly vital given the environmental impact of disposing of polymer-matrix composites, especially cured composites, with Europe generating roughly 400,000 tonnes of thermoset composite waste annually, a substantial portion of which is from Spain.

This study delves into the reuse and repurposing of polymer composites, promoting their integration within the Circular Economy to preserve material integrity and value. It showcases innovative repurposing projects in Spain and across Europe, such as transforming wind turbine blades into materials for construction, which demonstrates the feasibility of extending these materials' lifecycles. These efforts align with sustainability goals aimed at waste reduction and resource conservation. However, challenges persist, including matching waste volume and condition with market demands and scaling these practices effectively. The concept of structural re-use, turning cured composite waste into high-value, reusable products, highlights the potential of merging reuse and recycling strategies. Innovative approaches to reuse not only mitigate sustainability challenges but also foster economically viable solutions, marking a significant stride towards sustainable and efficient resource utilization in the composites sector.

Abstract

This chapter addresses the environmental and energy challenges posed by the increasing production of composite materials, particularly those reinforced with carbon and glass fibres. Current recycling technologies focused on fibre recovery, such as thermal and chemical methods, now enable the production of fibres suitable for reintegration into the value chain. The chapter details adapted textile technologies for processing these recycled fibres, covering methods from non-woven fabric production to the newest manufacturing technology of yarns and unidirectional tapes. Technologies such as carding and yarn formation are analyzed, highlighting the need for hybridization with virgin materials to enhance the mechanical properties of the final products. While current advances do not yet match the performance of virgin materials, ongoing research continues to optimize these processes, paving the way for the industrialization of more sustainable composites, with applications ranging from lightweight structures to sectors with higher mechanical requirements.

Abstract

The implementation of composite materials within the industry is a trend that has been developing for many years. In the case of the aeronautical industry, the gradual replacement of metallic parts by composite elements is increasing with each new aircraft model developed. However, these composites imply a challenge towards their end of life, since their dismantling and processing is under development, and they are currently processed as waste, with no recycling or reuse opportunities. In this context, a robotic dismantling solution is proposed by means of abrasive water jet cut, guided by a digital twin system. This system allows operator-guided cutting of the composite part, permitting the selection of the specific area to be dismantled on the aircraft itself. Thanks to a portable abrasive water jet system, operated by a collaborative robot, the cutting operations can be carried out in situ. This dismantling system is placed on a portable platform, operated by an AGV (Automatic Guided Vehicle) system integrated in the dismantling system itself, capable of transporting it along the working area. In this way, new strategies for dismantling and reusing the composite material at its end of life are proposed. These new options include the extraction of complete parts selected by the operator for their reuse, the elimination and/or recovery of rivets and the adaptation of the parts to be dismantled for a subsequent recycling process.

Abstract

If we want to maintain, or even increase, the current level of use of high-performance composite materials, some major challenges need to be solved: reduction in the cost of the final structure, reduction in energy consumption during the manufacturing cycle from the base material to the final structure, and develop strategies following the “5Rs Circular Economy” approach: Rethink, Refuse, Reduce, Reuse and Recycle technologies to produce materials and structures with high added value. This communication has the intention to show Airbus work on the reuse of multilayer uncured prepreg scrap generated in AFP, to be used for the manufacturing of non-loaded parts by BMC (Bulk Moulding Compound). We will deal with the problem understanding; multilayer prepreg scrap represents an important part of the fresh scrap generated in the manufacturing plants and no feasible technology has been yet developed to treat this type of residue due to the difficulty of separating layers without completely damaging the composite prepreg. We will also detail the multilayer prepreg scrap treatment, part production, material characterization, and the opportunities to introduce parts made of reuse prepreg on real aircraft.