Recycling of Carbon Fiber: Identification of Bases for a Synergy Between Recyclers and Designers

Abstract

In order to decrease both energy consumption and CO2 emissions, the automotive, aeronautics and aerospace industries aim at making lighter vehicles. To achieve this, composite materials provide good opportunities, ensuring high material properties and free definition of geometry. As an example, for cold applications, the use of carbon fiber/thermoset composites is ever increasing, in spite of a high fiber price. But in a global and eco-friendly approach, the major limitation for their use remains their potential recyclability. Recycling a composite means having a recycling technology available, getting a dismantle solution and an access for the product, and disposing identification plus selection possibilities to the materials. Thus, carbon fibers recovery (i.e. recycling and re-processing) would both help design engineers to balance energy efficiency and cost, and open new opportunities for developing second-life composites, dedicated to the manufacture of medium or low loaded parts (non-structural in many cases). A first section presents an overview of composite recycling possibilities. Indeed, environmentally and economically, composite incineration is not attractive (even with an energetic valorization), let-alone burying. Reuse and recycling thus remain the two most interesting options. Aeronautics offers a high potential in terms of fiber deposit. In southwest France, composites recycling will increase in terms of quantity due to dismantling platforms Tarmac (dedicated to civil aircraft applications) and P2P (for the disassembly of ballistic weapons). In addition, from a technical point of view, and even if end-of-life solutions for composites still remain under development, solvolysis (i.e. water under supercritical conditions) already offers the opportunity to recover carbon fibers. The resulting recyclate retains up to 90 percent of the fiber’s mechanical properties. A second part will explore the recycling to design issue (i.e. how recycling processes have to balance the previous aspects of the end-of-life proposal). The recycler clearly becomes a new supplier in the carbon fiber lifecycle, by revalorizing wastes with alternatives to burning. Moreover, increasing carbon fiber shelf life reduces its product life impact. Finally, promoting carbon fiber end-of-life would ensure to link aeronautics, automotive, and leisure and sports industries; but one can create demand for recycled reinforcement, by packaging it in useful and attractive forms for those end-users (e.g. pseudo-continuous fiber, felt, strips, bands, patches, etc.). These sections will be enlightened by several examples from collaborations between I2M and local industries.