Zero-Waste Recycling of Shelf-Cured Pre-Impregnated Carbon Fiber Reinforced Epoxy Laminae

The main objective of this study was to investigate a zero-waste restoration and reprocessing method of carbon/epoxy prepreg. We studied a series of chemical and thermal treatments to reshape and re-strengthen pre-impregnated (prepreg) carbon fiber-reinforced polymer (CFRP) composite rolls that were cured over the shelf, never been used, and would otherwise be discarded. The proposed treatment method is of high interest in minimizing solid waste and reducing the environmental footprint of polymer composites. We used a series of solvents (water, ethanol, N, N- Dimethylformamide (DMF) and Sulfuric Acid) to induce ductility in the scrap already rigid self-cured specimens. The chemical treatments of the scraps using mixtures of DMF-Water or DMF-Ethanol enhanced the ductility of the samples without any negative impact on the mechanical properties. However, the chemical treatment of scarps using a mixture of sulfuric acid with other solvents, could not improve the ductility of the samples. Heat pressing the chemically treated samples further enhanced the ductility of the samples and flattened the scrap composites. The recovered strength and modulus of the recycled prepreg CFRP reached a promising value of over 65% of the original properties, where the samples treated with a mixture of DMF-ethanol preserved their mechanical properties better than other treated samples. The simple, safe, and zero-waste recycling technique presented in this study has proven to be effective for closing the life cycle of a thermoset polymer composite.