Carbon fibers

Abstract

Due to steadily increasing amounts of carbon fiber reinforced polymers (CFRPs) used in a variety of applications (e.g., in transport area), increasing amounts of carbon fiber-containing waste are to be expected in the foreseeable future. Landfilling or incineration of CFRP waste streams are viewed critically. Therefore in this chapter mechanical, thermal, and chemical recycling routes are presented and their advantages and disadvantages are compared. Thermal recycling processes (especially pyrolysis) can be used to produce high-quality recycled carbon fibers (rCFs) that have no damage on the fiber surface and no residual matrix adherences. With every recycling process, fibers are also reduced in length, so that there is almost always a downcycling. Accordingly, it is difficult to find high-quality reuse opportunities for rCF. However, there is a lot of research on different reuse applications, which is also presented. The limits and future challenges of recycling are discussed, e.g., sensor-based separation of the CFRP, the characterization of the quality of rCF, or problems caused by contamination into other waste streams.