Recycling of shelf-cured pre-impregnated carbon fiber laminates

Abstract

Composites are light, strong, durable, and corrosion resistant materials that have the potential to offer significant structural and aerodynamic advantages for different applications. One of the most commonly used and reliable composites is the carbon fiber reinforced polymer pre-impregnated with an epoxy resin system, which includes the proper curing agent with a limited shelf life. This composite offers a near-perfect epoxy resin content that maximizes the strength properties of the fabric. This research work investigated a technology that will utilize pre-impregnated composites that were cured over the shelf and never-used, that would otherwise be discarded, which will help in managing the composites wastes. Also, it will reduce the cost of production of new materials when using the recovered end-of-life composites in different applications. Chemical treatment process was used to induce ductility in the scrap specimens to enable its reshaping by soaking them in different solvent mixtures of Sulfuric Acid (H2SO4), N, N-Dimethylformamide (DMF), Water and Ethanol. Heat treatment process was conducted to flatten and reshape the scrap composites and to improve its final mechanical properties. This study characterized the mechanical properties of the recycled material and the percentage of the original properties that could be retained. Moreover, the chemical properties were analyzed using Fourier-Transform Infrared Spectroscopy (FTIR) technique, Differential Scanning Calorimetry (DSC) instrument and Thermogravimetric Analysis (TGA). Also, the surface properties were characterized using Scanning Electron Microscope (SEM) and by determining the surface energy of the scrap and the treated specimens. Finally, the adhesion and reshaping of the recycled composites were illustrated to validate the applicability of the proposed recycling technique.