Mechanical and chemical combined recycling process for CFRP scraps

Composite materials are increasingly employed in many industrial sectors. Among others, carbon fibers are primarily used as reinforcing agents in high-performance composites with synthetic resin matrices such as epoxies, polyimides, vinyl esters, phenolics, and certain thermoplastics. However, when carbon fibers are coupled with thermosetting matrices, the resulting composites are not easily recyclable. When these products reach their end-of-life (EoL), there are several difficulties in their recycling and in the reuse of the carbon fiber reinforcement. Several recycling process methods exist, but one of the most promising and investigated in recent years is the mechanical one, which, unlike other approaches, does not require the use of high temperatures to decompose the polymeric matrix. However, the presence of residual matrix on the surface of the fibers negatively affects their potential reuse for the production of new composites. In comparison to well-known mechanical recycling methods such as shredding, crushing, and hammer milling processes, this work presents a combined recycling process comprising mechanical recycling by milling and a soft chemical treatment at temperatures significantly lower than those reached during conventional thermal recycling processes. Recycled fibers were then used to produce new composite laminates using an epoxy resin as the matrix. The effects of the chemical treatment on the adhesion between recycled fibers and the new resin were evaluated through pull-out and bending tests.