Systemic Circular Economy Solutions for Fiber Reinforced Composites

Circular Economy is an emerging production-consumption paradigm showing the potential to recover and re-use functions and materials from post-use, end-of-life, products. Even if several barriers still exist at different levels, from legislation to customer acceptance, the transition to this sustainable industrial model has been demonstrated to potentially bring economic, environmental, and social benefits, at large scale. Composite materials, which usage is constantly increasing, are composed by a fiber reinforcement in a resin matrix. Among them, the most widely adopted are Glass Fiber Reinforced Plastics (GFRP) and Carbon Fiber Reinforced Plastics (CFRP). Their applications range from wind blades to automotive, construction, sporting equipment and furniture. The post-use treatment of composite-made products is still an open challenge. Today, they are either sent to landfill, where not banned, or incinerated. The application of Circular Economy principles may lead to the creation of new circular value-chains aiming at re-using functions and materials from post-use composite-made products in high value-added applications, thus increasing the sustainability of the composite industry as a whole.

Composite materials are widely used in several industrial sectors such as wind energy, aeronautics, automotive, construction, boating, sports equipment, furniture and design. The ongoing increase in composites market size will result in relevant waste flows with related environmental issues and value losses if sustainable solutions for their post-use recovery and reuse are not developed and upscaled. The H2020 FiberEUse project aimed at the large-scale demonstration of new circular economy value-chains based on the reuse of End-of-Life fiber reinforced composites. The project showed the opportunities enabled by the creation of robust circular value-chains based on the implementation of a demand-driven, cross-sectorial circular economy approach, in which a material recovered from a sector is reused within high-added value products in different sectors. A holistic approach based on the synergic use of different hardware and digital enabling technologies, compounded by non-technological innovations, have been implemented to develop eight demonstrators grouped in three use cases, fostering different strategies. In particular, Use Case 1 focused on the mechanical recycling of short glass fibers, Use Case 2 on the thermal recycling of long fibers, while Use Case 3 focused on the inspection, repair and remanufacturing of carbon fiber reinforced plastics products and parts.

Considering the demanufacturing of large infrastructures (as wind blades and aircrafts) rich in composite materials, the most impacting step in terms of costs is disassembly. Different routes could be followed for dismantling and transportation and several factors influence the final result (as the technology used, the logistic and the administrative issues). For this reason, it is fundamental to understand which solution has to be followed to reduce the impact of decommissioning on the overall recycling and reusing cost. This work, after the formalization of the different possible disassembly scenarios, proposes a Decision Support System (DSS) for disassembly of large composite-rich installations, that has been designed and implemented for the identification of the most promising disassembly strategy, according to the process costs minimization. The mathematical models constituting the core of this tool are detailed and the DSS is applied to disassembly of onshore wind blades, underling the importance of similar systems to optimize demanufacturing costs.

Recycling of Glass Fibers Reinforced Plastics (GFRP) can be preferentially performed through mechanical processes due to the low cost of virgin fibers. Because of the poorer mechanical properties after comminution, the most interesting solution to reuse this material is a cross-sectorial approach, in which particles obtained through shredding of products from one sector are used in another sector. To allow this, a fine control on the particles dimension is fundamental, together with the minimization of operational costs. In this chapter, after a deep analysis on the available size reduction technologies and a preliminary feasibility analysis on the products involved in Use-Case 1 of the FiberEUse project, a 2-step architecture to optimize these two characteristics is presented. The models for both steps are shown and the developed solutions is applied to the End-of-Life products, demonstrating the potential of this approach, leading to optimal dimension of the particle with operational costs lower than both virgin fibers and disposal costs.

The possibility of recycling glass (GF) and carbon fibers (CF) from fiber-reinforced composites by using pyrolysis was studied. Different fibers from composite waste were recovered with thermal treatment. The recycled fibers were evaluated as a reinforcement for new materials or applications. The main objective was to evaluate the fibers obtained from the different types of industrial composite waste considering the format obtained, the cleanliness and the amount of inorganic fillers and finally, the fibers quality. These characteristics defined the processes, sectors and applications in which recycled fibers can replace virgin fibers. These fibers were also evaluated and validated with tensile testing and compared to the tensile strength of virgin GF and CF.

Three different classes of thermosetting styrene-free resins were investigated to assess their suitability to constitute the matrix phase in the reformulation of composites reinforced with mechanically recycled glass fibers. Resin reactivity and mechanical properties after curing were compared to commercial styrene-based, unsaturated polyester resins. The polymeric resin, acting as a binder, could be properly selected depending on the desired reactivity, processability, and mechanical behavior. Some prototypal examples of reformulated composites with different types and contents of recycled glass fibers were produced and mechanically tested. The combination of the epoxy resin with up to 60 wt% of mechanically recycled glass fibers resulted in an increase of elastic modulus up to 7.5 GPa.

The mechanical performance of a composite is greatly related to the load transfer capability of the interface between the matrix and the reinforcing fibers, i.e. the fiber/matrix adhesion, which is enhanced by a surface treatment called sizing. The original sizing of reinforcing fibers is removed during recycling process, which is recognized to contribute in typical issues of recycled fibers, namely uneven fiber properties and poor fiber/matrix adhesion. Applying a new sizing, a process denoted here as resizing, can help mitigate the issues. Furthermore, the sizing has a major role in improving the processability of the fibers as it contributes to the distribution of the fibers in the matrix. Proper distribution, along with the fiber fraction, are highly important for the composite performance. These properties are ensured by proper compounding. Here we demonstrate and validate the process steps to resize and compound recycled glass and carbon fibers with thermoplastic matrices. We found that at a relatively high sizing concentration, the compounding of all tested material combinations was possible. The resizing of the recycled fibers improved the compatibility at the fiber/matrix interface. It was concluded that recycled fibers can be used to replace virgin fibers in automotive industry to allow weight reductions and to promote circularity.

An additive remanufacturing process for mechanically recycled glass fibers and thermally recycled carbon fibers was developed. The main purpose was to demonstrate the feasibility of an additive remanufacturing process starting from recycled glass and carbon fibers to obtain a new photo- and thermally-curable composite. 3D printable and UV-curable inks were developed and characterized for new ad-hoc UV-assisted 3D printing apparatus. Rheological behavior was investigated and optimized considering the 3D printing process, the recyclate content, and the level of dispersion in the matrix. Some requirements for the new formulations were defined. Moreover, new printing apparatuses were designed and modified to improve the remanufacturing process. Different models and geometries were defined with different printable ink formulations to test material mechanical properties and overall process quality on the final pieces. To sum up, 3D printable inks with different percentages of recycled glass fiber and carbon fiber reinforced polymers were successfully 3D printed.

Coating processes are emerging for new applications related to remanufactured products from End-of-Life materials. In this perspective, their employment can generate interesting scenarios for the design of products and solutions in circular economy frameworks, especially for composite materials. This chapter would give an overview of coating design and application for recycled glass fiber reinforced polymers on the base of the experimentation made within the FiberEUse project. New cosmetic and functional coatings were developed and tested on different polymer composite substrates filled with mechanically recycled End-of-Life glass fibers. Afterwards, recycled glass fiber reinforced polymer samples from water-solvable 3D printed molds were successfully coated. Finally, new industrial applications for the developed coatings and general guidelines for the coating of recycled glass fiber reinforced polymers were proposed by using the FiberEUse Demo Cases as a theoretical proof-of-concept.

For the reuse of components and structures made of fiber composite materials, a complete remanufacturing process chain is necessary to prepare the parts for a further life cycle. The first step is to dismantle the parts to be reused. Fiber composite components are mostly joined using adhesive technology, so that solution techniques are required for adhesive connections. One possibility is the separation of the adhesive layer by means of thermally expanding particles. Adhesive residues are removed by laser so that the components can be glued again after reprocessing. The decisive factor for which process is used for the remanufacturing of the components is the state at the end of the life cycle. Non-destructive testing methods offer a very good option for detecting damage, planning necessary repairs and direct reuse of damage-free components. Repairs to fiber composite structures have been carried out in aviation for a long time and are accordingly established. These processes can be transferred to the repair of automotive fiber composite components. Many technical solutions were developed and tested as part of the project. Future research work is aimed at further development, particularly with regard to the automation of the technologies in order to enable an industrial application of the recycling of automobile components made of fiber composites.

The involvement of designers in the sustainable transition from linear to circular economy is crucial since they significantly contribute to the realization of products and services. In the FiberEUse project, a multiple-step approach to co-design was employed, starting with the definition of a first and second design brief in order to clarify the task objectives for designers. This was followed by the description of the co-design process, which aims to engage designers to contribute innovative design concepts for recycled composites. By publishing design concepts in the feedback collection software module Idea Manager, designers and users were able to exchange information, insights, visions, and thoughts digitally. The Idea Manager comprises a feedback collection tool that supports a first assessment of design concepts. Depending on the design briefing and/or confidentiality agreements, the feedback collection and the assessment can either be done (stakeholder-)internally or publicly. A flowchart illustrates the multi-step approach of co-design within the FiberEUse project. The feedback collection process was aided by a progress analysis to detect new value chains for business cases. For the selection of product design concepts, a progress analysis partitioned into four main criteria, the following aspects are drawn on for assessment: (i) quantitative and qualitative production feasibility, (ii) closeness to market introduction, (iii) potential volume of the market, (iv) circularity, (v) type of market, (vi) service opportunities, and (vii) take-back/deposit systems. Aside from bringing out the advantages of co-design for consumers as well as production companies, this chapter also discusses general challenges of co-design and co-creation in a broader sense when intellectual property rights (IPR) are not respected appropriately. The participation in a publicly accessible co-design of concepts must be clearly communicated and accepted by each participant by agreeing to intelligible terms and conditions.

The design of reusable composite structures for cars needs high constructional effort. The car must be divided into separable modules meeting ecologic and economic requirements. Here, a battery containing platform and a seating structure were selected as large components with high potential for reuse. In a first step the desired car is described setting the basic scenario. A carsharing vehicle shows perfect conditions due to low logistics effort and the business model of the owner. This sets the boundary conditions for the design of the platform. Two different approaches were tested and merged into a concept ready for reuse. Simulations of the stiffness and the crash performance show good values. First large CFRP profiles were produced in a complex pultrusion process. An associated seating structure following similar design principles was constructed using profiles and nods. All load-cases that can occur during the utilization phase could be beared. Both modules together can form the basis of a reusable car. The design principles like detachable joints—in particular the utilization of detachable adhesive connections—can be adapted for any other technical composite product.

‘Product re-design guidelines’ outline the rethinking of consumer and capital goods design in a context of a transition from a current linear economy towards a circular-oriented economy. These guidelines deliver generalized quality standards addressing various target groups who are to be engaged in order to achieve sustainable results. The definition of crucial counterparts of a system or beneficiaries, respectively, changes the guidelines’ discuss factors that are fundamental for the integration of sustainability aspects into existing and/or novel business models. With regard to the circular progression in future, awareness building for improvements in disassembling and remanufacturing will remain essential among designers and producers.

The FiberEUse IT platform is a tool that enables the exchange of information among stakeholders working into and crossing the glass and carbon fibers value chains. The list of stakeholders had been identified and is listed into the document. The list of users of the platform is also listed into the document, although it is not fixed. During the collection and analysis of the requirements, the circularity of the approach had been in the core focus. This drove to the identification of solutions able to cover all the different and innovative aspects of a Circular Economy Systemic Innovation. New products, new processes, new materials, new connections, quick and unexpected introductions of innovations, methodological approach, end of waste concept, availability of objects for dismantle, not-standardized parameters, are only some of the aspects arisen analysing deeply the requirements. They have all been approached in the platform which is by definition circular, dynamic, expandable and polymorphic. In the FiberEUse project, the validation activities of the IT platform had adopted an agile approach involving demonstrators during the preliminary phases of analysis, and mock-up creation. An internal technical validation had been completed. The methodology had been adopted and main results are reported in Sect. 5.

The main objective of Use Case 1 is the development of industrial demonstrators of new products incorporating mechanically recycled glass fiber composites. These demonstrators will determinate the technical feasibility and cost effectiveness for glass and carbon fibers recycling solutions. The demonstrators include structural parts like a ski by HEAD Sport and sanitary products like shower trays by Novellini where the recycling fibers are used for existing products. A series of design concepts have been developed supported by a design briefing and a co-design methodology for street furniture and similar products, where the recycled materials are already considered from the start of the design of the product.

This chapter describes the industrial demonstration of the reuse of recycled fibers obtained by a thermal process. Four demonstrators are described in which both recycled carbon fibers and recycled glass fibers have been incorporated into different matrices. The automotive sector proposes 3 demo cases (Pedal Bracket, Front-end carrier and Cowl top support) with demanding mechanical and thermal requirements. These components were manufactured by injection molding with thermoplastic matrices. The construction sector proposes 1 demo case (Light transmitting single skin profiled sheet.) with mechanical and light transmittance requirements that was manufactured by continuous lamination. It is demonstrated that the incorporation of recycled fiber for these applications is technically possible, fulfilling the requirements demanded by each sector.

Cars designed for reuse are a novelty. The disassembly and remanufacturing of major vehicle structures is not an established process yet. This means new tasks and within that, new business models must be found to close the loop. New facilities and logistics are part of the process chain. In this chapter the processes will be outlined on basis of a car-sharing vehicle as an example of a fleet ownership. The reusable platform and the seat structure are the basis of this model-based consideration. The technical issues and obstacles will be discussed as well as economic and ecologic questions.

Currently the development of new circular materials has brought up the necessity to transfer their knowledge amongst the interested stakeholders for their real exploitation. This chapter aims to illustrate the design of a physical and virtual library system of the FiberEUse project. In particular, this library system wants to foster the development of new applications and value chains through the showcase of the new recycled composite materials and archetypal remanufactured products developed during the project. After the definition of the system concept, specific taxonomies were designed for the physical and virtual parts considering the technical properties and the expressive-sensorial qualities of the new recycled materials and products. A hierarchical organization was then designed to allow both tangible and intangible interactions with the samples, resulting in a coherent experience to explore these new recycled materials. Meanwhile, the physical exhibitors and the library website were developed to collect the physical and virtual samples. At the end, the whole system will be freely accessible through the library website and by booking a visit to the physical part. Thanks to its transdisciplinary nature, this system can stimulate the real exploitation of new value chains and applications.

The growing use of composites in various industries such as aerospace, automotive and wind turbine has increased environmental concerns regarding their waste disposal methods. Deploying circular economy practices to reuse composites could play a crucial role in the future. In this regard, this chapter addresses the development and implementation of new business models for composites re-use, as fundamental enabler for the industrial exploitation and diffusion of technological and methodological innovations developed in the FiberEUse project. Seven products were chosen as representatives for composites reuse application in four industrial sectors: sanitary, sports equipment, furniture and automotive. Re-use business models are presented describing their value proposition, with particular reference to the provision of advanced product-service bundles, the revenue models (including schemes such as leasing), as well as new supply chain configurations entailing new partnership between producers and recyclers to access post-use composites to re-use. Given the importance of reverse supply networks, the potential reverse logistics pathways for mechanical recycling of Glass Fiber Reinforced Plastic (GFRP), thermal recycling of Carbon Fiber Reinforced Plastic (CFRP) and remanufacturing of CF composites waste in Europe for 2020 and 2050 have been investigated. We concluded that the optimal reverse logistics network needs to be decentralized in more than one country in Europe. Therefore, it is suggested that policy makers address regulation to allow the transportation of waste between European countries to facilitate the development of recycling networks for composites reuse.

Circular economy business models are key enablers of the circular economy. However, they must also be economically viable to materialize in reality, since profitability is a major business driver. Assessment of the economic potential of circular economy business model is subjected to significant uncertainties and to a range of risks, due to their novel nature. This chapter firstly discusses the economic assessment of the circular business models specifically for composites, based on five business model cases from various sectors, focusing on the identification of the major causes of uncertainty and then performing sampling-based sensitivity analysis to investigate the viability of the circular economy business models under uncertainty. The findings show that the proposed circular economy business models are not always more profitable than the existing models. Thus, in some instances new market stimulus would need to be identified and implemented to increase attractiveness of the proposed solutions. As a consequence, the chapter identifies and prioritizes risk factors for new circular economy business models for composites. The risk analysis uses input from industry experts and the literature to come up with a key risk factors list relevant to circular economy business models for composite materials. The risk analysis concludes that the key risk factors are both from the demand/market and supply side.

The effect of legislation on composites recycling can be both a driving force, such as in the case of End-of-Life Vehicle legislation, that is making it mandatory to reuse the materials used in vehicle manufacturing, or a boundary, increasing the burden to manufacturers reusing composite materials. As a consequence, a deep study on the impact of policies on the reuse of composites is fundamental to promote those actions boosting the deployment of circular value-chains. In this Chapter, a model based on System Dynamics theory, representing the entire industrial environment of composite materials, has been developed, leading to a prioritization of most impacting legislations, providing conclusions and recommendations derived from data.