Abstract

Reprocessable, repairable, and recyclable thermoset composites have the potential to improve the circularity of composites and ensure their sustainability. Disulfide-based epoxy matrices are under development to meet the specifications of key sectors (transport, wind energy, etc.). The manufacturing of reinforced composites by different techniques (infusion, prepregs, etc.) has been validated (TRL 4-5). The incorporation of new functionalities, such as fire resistance, and the validation of recycling are now on the table. Conventional chemical recycling separates the reinforcement from the composite for reuse, leaving aside the polymer matrix. The new functionalities incorporated require recovery and validation of the matrix. Dynamic resins allow milder conditions to be applied during recycling, and the challenge remains to find new applications that reuse these recycled products. On the other hand, the rational use of resources demands for new recycling routes that do not require separation of the components, apply few steps, be economically viable, and maintain the value of the reinforcement and the matrix. Vitrimers allow the thermoforming of composite parts through the application of heat and pressure. This process opens the way from reusing final parts with new shapes to generating short new fibre composites from mechanical pre-crushing. This communication will present the latest developments and objectives of several European projects funded under the HE framework (SURPASS, GA no. 101057901; MC4, GA no. 101057394) in which work on the maturity of the technologies is in progress.

Abstract

This chapter presents a review of the current situation in Spain, in relation to Europe and the world, regarding the treatment of composite materials and their constituents at the end of their life cycle. Such treatment may include landfill disposal, energy recovery (incineration), recycling or recovery of materials as raw materials for the same or other uses, or the reuse or repurposing at the component or subcomponent level. These pathways or processes, along with associated developments and research, are described in greater depth in subsequent sections, while this section provides a general, combined, and particularized review, as much as possible, of the Spanish case. The chapter covers three main areas: a general framework, a section on initiatives and services offered by private companies, and a section on the activities of groups, centers, and entities within the R&D sector. Issues related to legislation, including waste classification, are presented in a specific chapter dedicated to this topic.

Abstract

This chapter describes the different strategies that can be carried out with polymeric matrix composite materials once they have passed through the recycling centres currently available on an industrial scale.

The work describes how, depending on the nature of the matrices, as well as the fibers, the reuse of this type of fiber should be directed towards one type of process or another and how, through diverse technologies, it is possible to develop products with a greater or lower fiber orientation. In the same way, the chapter collects information on how some composite manufacturing processes can affect the fiber length and therefore modify the final properties of the product.

Thus, the different technologies currently available and under development in Spain with focus on giving a new life to carbon and glass fibers, while retaining most of their added value and properties, are described. Namely, reuse in thermoset composites, reuse as reinforcement in thermoplastic composites, fiber re-processing (woven or non-woven fiber structures), recycling of fibres that are still embedded, recycling specific to the nature of the fiber.

Throughout the text, some of the projects led by Spanish entities with the greatest relevance in the development of the different technologies are collected. At the end of the text, these same projects and others are highlighted, remarking the work carried out by Spanish centres, universities and companies in the field of re-using and recycling of carbon and glass fibers.

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

One of the main problems of composite recyclability, is to find applications with a positive business case and technically viable. In order to determine possibilities, it is necessary, first, to analyze mechanical properties of materials as well as today available manufacturing processes with this type of products.