Effects of processing and storage conditions on recycled carbon fiber/epoxy composites from uncured prepreg scraps

Recycling of solid wastes such as carbon fiber-reinforced polymer composites from the aerospace and automotive industries is an urgent task. This work reports a process for the reuse of uncured prepreg wastes containing carbon fibers and epoxy resins to produce new composites using thermal compression molding and thermal vacuum bagging techniques. With this process, the composite was completely cured with a processing time of 20 min at 170°C. The tensile and flexural strength of the material obtained a maximum of 353.35 MPa and 374.58 MPa for compression molding, and 221.39 MPa and 310.84 MPa for vacuum bagging at 25 min. However, the tensile and flexural strength decreased significantly when the processing time was prolonged to 30 min. In contrast, their tensile modulus increased with a longer processing time. Furthermore, the DSC and mechanical analysis data indicate that the prepreg scraps stored at −2°C are better than those stored at 7°C. After 3 days stored at −2°C, only 10% of the epoxy had cured, and the tensile strength remained nearly unchanged. These initial investigations indicate a potential application in producing novel composite materials from the reuse of uncured prepreg scraps, with appropriate storage conditions to achieve high recycling efficiency.