Reuse of Carbon Fibers and a Mechanically Recycled CFRP as Rod-like Fillers for New Composites: Optimization and Process Development

The rising amount of carbon fiber reinforced polymer (CFRP) composite waste requires new processes for reintroducing waste into the production cycle. In the present research, the objective is the design and study of a reuse process for carbon fibers and CFRP by mechanical recycling consisting of length and width reduction, obtaining rods and reintegrating them as fillers into a polymeric matrix. Preliminary studies are carried out with continuous and discontinuous unidirectional fibers of various lengths. The processing conditions are then optimized, including the length of the reinforcement, the need for a plasma surface treatment and/or for resin post-curing. The resin is thermally characterized by differential scanning calorimetry (DSC), while the composites are mechanically characterized by tensile strength tests, completed by a factorial design. In addition, the composites tested are observed by scanning electron microscopy (SEM) to study the fracture mechanics. Optimal processing conditions have been found to reduce the reinforcement length to 40 mm while maintaining the mechanical properties of continuous reinforcement. Furthermore, the post-curing of the epoxy resin used as matrix is required, but a low-pressure plasma treatment (LPPT) is not recommended on the reinforcement.

Automated summary

This research aims to design and study a mechanical recycling process for the reuse of carbon fibers and CFRP composites. The process involves reducing the length and width of the materials, obtaining rods, and reintegrating them into a polymeric matrix as fillers. Preliminary studies are conducted with various lengths of continuous and discontinuous unidirectional fibers, followed by optimization of processing conditions including reinforcement length, plasma surface treatment, and resin post-curing. The resin is thermally characterized using differential scanning calorimetry (DSC), and the composites are mechanically characterized using tensile strength tests and factorial design. The composites are also observed through scanning electron microscopy (SEM) to study fracture mechanics. Optimal processing conditions have been identified, reducing the reinforcement length to 40 mm while maintaining the mechanical properties of continuous reinforcement. Additionally, post-curing of the epoxy resin matrix is required, but low-pressure plasma treatment (LPPT) is not recommended for the reinforcement.