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

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

In terms of energy, the Earth is an open system: it constantly receives energy from solar radiation and emits the same amount of energy in the form of more degraded radiation; the displacement of the equilibrium point between these two flows due to the growth of greenhouse gases, increases the average temperature of the Earth and causes climate change. On the other hand, in relation to matter, the Earth is a closed system, apart from the sporadic fall of some meteor. Nature has the ability to regenerate the organic materials of living beings but not with many other materials.

Today, the volume of materials involved in human activities is 12.5 tons per person per year (1.5 to 4 times more in rich countries): 25% of the total comes from biomass (including food), 15% are fossil fuels, 10% are metal ores, 42% are other minerals (mainly for construction) and 8% are recycled. On the other hand, obtaining and transporting materials worldwide requires more than 40% of the energy of the human system, a value that is growing with the use of increasingly rare, scarce and dispersed materials. The overexploitation of resources coupled with the increasing use of non-renewable energy resources (fossil fuels and uranium), with the consequent energy and climate crisis and the deterioration of the environment, leads both to a change in the energy model and to rethinking the practices today dominant of continuous economic growth and the linear economy based on extract-use-throw.

The purpose of this communication is, after presenting the figures on the global metabolism of materials, to reflect on some of the new attitudes and actions that will need to be adopted within the framework of sustainable development. By way of example, the following are cited: 1) Moderate, reduce, eliminate the use of materials where possible; 2) Extend the life of goods and material infrastructures; 3) Reuse, recover, recycle materials; 4) Return as much as possible biologically based materials, more recyclable; 5) Avoid, as far as possible, technologies based on rare or scarce materials; 6) Avoid the dispersion of materials in the environment (atmosphere, water, soil); 7) Encourage the use of local materials in order to minimize transport and its energy impact; 8) Take care of the quality and good health of basic resources: air, water and fertile soil.

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.